practice

Explanation

Metronidazole forms toxic free radical metabolites in the bacterial cell that damage DNA. It is bactericidal, and an antiprotozoal. It is used to treat Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (bacteroides, Clostridium difficile). It can be used with a proton pump inhibitor and clarithromycin for “triple therapy” against Helicobacter pylori.

Entamoeba histolytica causes amebic dysentery.

Explanation

Autosomal dominant: often due to defects in structural genes. Many generations, both male and female are affected. Found in every generation; no generation is left out (skipped). Parent – child in every generation.

Autosomal recessive is usually seen in some generations (other generations are skipped).

It is sex linked, if only males or only females(X-linked) are affected.

Dominant because no generation was skipped(father-daughter). Only girls were affected, therefore it is X-linked (sex linked) because a father donates an x-chromosome to the daughter.

 father - XY;

mother - XX

  A father determines the gender of a child, if he gives an X-chromosome, then the child will be a female, and if he gives a Y-chromosome then the child will be a male.

Explanation

In an adult, erythrocyte, granulocytes, monocytes and platelets are formed in the red bone marrow (RBM); lymphocytes are also formed in the RBM and in the lymphatic tissues. Hemopoiesis (hematopoiesis) includes both erythropoiesis and leukopoiesis as well as thrombopioesis (development of platelets). Erythrocytes develop from the multipotential myeloid stem cell under the influence of erythropiotein. The erythropiotein-sensitive erythrocyte progenitor cells give rise to the first recognizable erythrocyte precursor, the proerythroblast.

Proerythroblast → basophilic erythroblast → polychromatophilic erythroblast → orthochromatophilic erythroblast (normoblast) → polychromatophilic erythrocyte (reticulocyte) → Erythrocyte.

       In normal blood, reticulocytes (new erythrocytes) constitute 1-2% of total erythrocyte count.

Explanation

Secondary immunodeficiency occur after full development of the immune system. Chronic virus infections (e.g. infectious mononucleosis caused by Epstein-Barr virus) and HIV (human immunodeficiency virus) may cause secondary immunodeficiencies. HIV → CD4 cells; Epstein Barr virus (EBV) → B lymphocytes (B cells).

Explanation

Fibroma is a benign connective (fibrous) tissue tumors. It can be hard (dense) or soft fibroma. Hard fibroma has fibrous connective tissue (e.g. collagen fibers) prevail over the cellular elements. Soft/loose fibroma has more cells than the connective tissue component.

In the question; fascicles of divergent collagen fibers with SOME fusiform cells irregularly distributed among the fibers i.e. fibers > cells (fibers dominate).

Explanation

Hemorrhagic syndrome can develop from surgery for excision of a cyst on pancreas. Pancreas contains inactive proteolytic enzymes which can be accidentally released during surgery on pancreas). Most of the clotting factors are proteins in the form of enzymes. Normally, all the factors are present in the form of inactive proenzyme which must be activated into enzymes by proteolytic enzymes. Likewise, in fibrinolysis plasmin is formed from inactivated glycoprotein called plasminogen..All these inactive enzymes can be activated, if the proteolytic enzymes and lysosomal enzymes specifically cathepsin with trypsinogen in pancreas are accidentally released during surgery. Cathepsin activates trypsinogen to trypsin leading to further activation of other molecules of trypsinogen and plasminogen can now be converted into its active form plasmin. This systemic activation of plasminogen into plasmin cause generalized fibrinolysis – removing blood clots.

Explanation

Erythropoietic porphyria (Gunther’s disease): This disorder is due to a defect in the enzyme Uroporphyrinogen III cosynthase. It is characterized by:

* It is a rare congenital disorder caused by autosomal recessive mode of inheritance, mostly confined to erythropoietic tissues.

* The individuals excrete Uroporphyrinogen I and Coproporphyrinogen I which oxidize respectively to Uroporphyrin I and Coproporphyrin I (red pigments).

* The patients are photosensitive (itching and burning of skin when exposed to visible light) due to the abnormal porphyrins that accumulate. Porphyrins are accumulated in the teeth, bones and an increases amount are seen in the plasma, bone marrow, faeces, RBCs and urine.

* Increased hemolysis is also observed in the individuals affected by this disorder.

Explanation

Maple syrup urine disease results from blocked degradation of branched amino acids (isoleucine, leucine, valine) due to decreased activity or deficiency of α-ketoacid dehydrogenase. It causes increase α-ketoacids in the blood, especially those of leucine. It also causes severe CNS defects, intellectual disability and death. It is an autosomal recessive disease. Urine smells like maple syrup/burnt sugar. Treatment: restriction of isoleucine, leucine, valine in diet and thiamine supplementation.

Explanation

Spirochetes are thin-walled, flexible, spiral rods. Three (3) genera of spirochetes cause human infection: Treponema (syphilis and the nonvenereal treponematoses); Borrelia (lyme disease and relapsing fever); Leptospira (leptospirosis). Treponema pallidum are thin, tight, spirals seen by darkfield illumination, silver impregnation or immunofluorescent stain.

Syphilis (lues) is a sexually transmitted disease of mankind caused by the spirochete – Treponema pallidum. Stages of syphilis are: primary (chancre); secondary (disseminated) and Tertiary (with lesions of deep organs following a latent period of 2 – 20 years or more).

The chancre develops at the site of inoculation in 10 – 90 days (average 21 days) and has a characteristic “luetic vasculitis” (endovasculitis, perivasculitis) in which endothelial cells proliferate and swell and the walls of the vessels become thickened by lymphocytes and fibrous tissue. Syphilis can also produce fibrinoid or caseous necrosis (gumma).

Explanation

Coli titer is the smallest amount of water where 1 E.coli is present.

Coli index is the amount of E. coli in 1 liter of water.

            2 E.coli   -  500ml

            1 E.coli   -  ?

                        ? = 250

Therefore, Coli titer = 250

1 liter of water  =  1000ml

            2 E. coli   -  500ml

                   ?       -   1000ml (1L)

                        ? = 4

Therefore, Coli index = 4

Coliform index (Coli index) and Coli titer are used to rate the purity of water, soil and air based on the count of fecal bacteria by testing for coliforms especially the well known Escherichia coli (E. coli).

Explanation

Diphtheria bacteria (Corynebacterium diphtheria) is Gram positive, pleomorphic, often club-shaped rods and are arranged in palisades or in V (at an angle) or L-shaped formations. Media used for isolation are Tellurite agar & Lὄffler medium. Lὄffler nutrient medium consists of coagulated serum & nutrient broth. Selective indicator medium containing tellurite are used in selective culturing. K tellurite is used to inhibit the accompanying flora.

Explanation

Hematocrit or packed cell volume (PCV) is the proportion of blood occupied by RBCs expressed in percentage. It is the volume of RBCs packed at the bottom of a hematocrit tube when the blood is centrifuged.

    * Increases in hematocrit can be seen in polycythemia, dehydration, dengue shock syndrome [Dengue fever (tropical disease caused by flavivirus transmitted by the mosquito Aedes aegypti) of grade III or IV severity]

    * Decrease in hematocrit can be seen in Anemia, Cirrhosis of liver, Pregnancy, Hemorrhage (which can be due to ectopic pregnancy).

Explanation

Explanation

A large number of components are required for translation (synthesis of a protein). These include all the amino acids that are found in the finished product, the mRNA to be translated, tRNA, functional ribosomes, energy sources and enzymes as well as protein factors needed for initiation, elongation and termination of the polypeptide chain. In eukaryotic cells, the ribosomes are either “free” in the cytosol or are in close association with the endoplasmic reticulum (which is then known as the “rough” endoplasmic reticulum or RER). The RER – associated ribosomes are responsible for synthesizing proteins that are to be exported from the cell as well as those that are destined to become integrated into plasma, endoplasmic reticulum or golgi membranes or incorporated into lysosomes.

Explanation

     Pharmacokinetics refers to what the body does to a drug. Once a drug is administered through one of several available routes, 4 pharmacokinetic properties determine the speed of onset of drug action, intensity of the drug’s effect and the duration of drug action: absorption, distribution, metabolism and elimination.

Absorption: first, drug absorption from the site of administration permits entry of the therapeutic agent (either directly or indirectly) into plasma. Absorption is the transfer of a drug from its site of administration to the bloodstream via different mechanisms.

Methacycline is a tetracycline. All tetracyclines are adequately absorbed after oral ingestion. However, taking these drugs concomitantly with diary foods in the diet decreases absorption due to the formation of nonabsorbable chelates of the tetracyclines with calcium ions. Nonabsorbable chelates are also formed with other divalent and trivalent cations e.g. those found in magnesium and aluminum antacids and in iron preparations. This presents a problem if a patient self-treats the epigastric upsets caused by tetracycline ingestion with antacids.

Nonforming CO₂ antacids: aluminum hydroxide + magnesium hydroxide = Almagel or Maalox.

Explanation

Atherosclerosis is a multifactorial disease that affects the intima of elastic arteries. Pathogenesis of atherosclerosis has 3 stages: 

   * Endothelial injury is accompanied by attachment of monocytes, platelets and thrombus formation.

   * Macrophages in the intima phagocytize lipid and transform into foam cells. Macrophages also secrete growth factors that stimulate the proliferation of smooth muscle cells.

   * Ruptured atheromas release thrombogenic material into the circulation causing thrombus for intimal ulceration.

Explanation

       Due to incomplete closure of the tricuspid valve during right ventricular systole, part of blood is regurgitated into the right atrium, where it is mixed with the normal volume of blood delivered from the venae cavae which makes the atrium become distended and hypertrophied. During diastole, a larger volume of blood is delivered into the right ventricle because the portion of blood that was regurgitated into the atrium during systole is added to the normal volume of blood delivered → ↑volume (heart overload). This causes dilatation and hypertrophy of the right ventricle. Compensation in this disease is attained by intensified work of left ventricle which leads to its hypertrophy too. The mass of the circulating blood usually increase proportionally to the degree of circulatory insufficiency. This is favored by retention of sodium chloride and water in decreased renal filtration and increased reabsorption of sodium and the increasing number of RBCs (hypoxia is attended by intensified hemopoiesis to compensate for the developing insufficiency) → ↑blood volume.

Explanation

Gonorrhea is caused by Neisseria gonorrhoeae. Its often intracellular (within neutrophils), gram-negative diplococci.  It is sexually or perinatally transmitted.

Syphillis is caused by Treponema pallidum(spirochetes),  Chancroid is caused by Haemophilus ducreyi. Trichonomoniasis is caused by trichomonas vaginalis. Veneral lymphogrnaulomatosis is caused by Chlamydia trachomatis (L1-L3).

They are all sexually transmitted.  Specific identification of the gonococcus can be made either by its fermentation of glucose (but not maltose) or by fluorescent-antibody staining.

Explanation

     Proserin (Neostigmine) is an indirect acting cholinergic agonist (anticholinesterase). It preserves endogenous acetylcholine which can stimulate a greater number of acetylcholine receptors at the muscle endplate. Halothane, on the other hand, is a general anesthetic that breaks neurotransmission. Proserin stimulates and aids neurotransmission, while halothane breaks neurotransmission (antagonism). This is done indirectly because they don’t act by the same mechanism to antagonize each other. It is functional because each drug weakens the other’s action/effect.

Explanation

Microvascular complications of Diabetes Mellitus:

* Eye: retinopathy, cataracts, glaucoma

* Kidney: nephropathy - kidney failure, microalbuminuria, gross albuminuria

* Nerves: neuropathy - peripheral autonomic

There are 3 main metabolic pathways in the pathogenesis of chronic complications of DM:

        * Non enzymatic glycosylation

        * Intracellular hyperglycemia

        * Activation of protein kinase C

Nonenzymatic glycosylation: Glucose binds to the amino groups of proteins [reflected in glycosylated hemoglobin A (HbA1c)], repetitive glycosylation eventually results in cross-linking of proteins leading to dysfunction. These products accumulate in vessel walls (e.g. blood vessels of the eye). Glycosylation also occurs with lipids and nucleic acids.

Explanation

As far as the lungs in fetus are inactive, the pulmonary arteries receive but little blood; so the greater portion of the venous blood that enters the pulmonary trunk drains to the aorta via wide ductus arteriosus (botallo’s duct). The duct connects the bifurcation of the pulmonary trunk to the concave portion of the aortic arch. Nonclosure of ductus arteriosus – Patent ductus arteriosus: In this case, the aorta (with relatively high blood pressure maintained) shunts the blood to the pulmonary trunk via the patent ductus arteriosus. This results in pressure increase within the pulmonary route and hypertrophy of both ventricles. This excessive shunting causes blood deficiency in the descending aorta and reduced blood supply to related organs. This in turn leads to marked growth retardation in children.

Explanation

Evaporation is a way the body dissipates heat to the environment by its evaporation via sweat or evaporation of moisture from the skin and respiratory tract mucous membranes of (“wet” heat loss). Evaporation closely related to relative humidity.

Heat Radiation is a way the surface of the human body emits heat to the environment in the form of infrared rays. The amount of heat the body radiates to the environment is proportional to the surface of radiation area and to the difference between the mean values of skin and environment temperature. The surface radiation area is the total surface area of body parts that contact the air. Elimination of heat by radiation increases with a decrease in ambient temperature and decreases with its increase. It is possible to reduce elimination of heat by radiation via reduction of the surface of radiation area (“winding oneself into a ball”). Heat radiation does not require a medium for transfer of heat. (Key words: naked or lightly clothed).

Convection is a way the body eliminates heat by means of transferring heat via moving particles of air or water. To dissipate heat by means of convection, body surface shall be airflowed at a temperature that is lower than the temperature of the skin. At that, air layer contacting with the skin warms up, decreases its density, rises and is replaced by cooler, denser air. By increasing the speed of the air flow (wind, ventilation) heat emission increases significantly as well (forced convection). Convection requires convection current; current of gases or liquids (Key words: air over exposed area of skin).

Conduction is a way the body eliminates heat by means of direct contact with another object. Heat is transferred down the temperature gradient (i.e. from the object of higher temperature to the object of lower temperature). Conduction requires contact with another object (Key words:  in water).

Explanation

Hemophilia is a group of sex-linked inherited blood disorders characterized by prolonged clotting time. However, the bleeding time is normal. Usually, it affects the males, with the females being the carriers. Hemophilia occurs due to lack of formation of prothrombin activator. That is why the coagulation time is prolonged. The formation of prothrombin activator is affected due to the deficiency of factors VIII, IX or XI.

   Types of hemophilia: 

*Hemophilia A or classic hemophilia - deficiency of factor VIII (X-LINKED RECESSIVE)

*Hemophilia B or Christmas disease - deficiency of factor IX (X-LINKED RECESSIVE)

*Hemophilia C or factor XI deficiency (AUTOSOMAL RECESSIVE)

It will be passed to the sons – the mother is the carrier.

Explanation

      A transplanted heart is denervated, so no nervous stimulation can increase or decrease the heart rate or cardiac output. Therefore, the only mechanism capable of increasing minute blood volume is the catecholamines (epinephrine/adrenaline; norepinephrine/noradrenaline).

Explanation

·        Diphyllobothrium latum causes diphyllobothriasis. A fish tapeworm. In contrast to the other cestodes, which have suckers , the scolex of D. latum has two elongated sucking grooves by which the worm attaches to the intestinal wall. Infection by D. latum causes little damage in the small intestine. In some individuals, megaloblastic anemia occurs as a result of vitamin B₁₂ deficiency caused by preferential uptake of the vitamin by the worm. Transmission: ingestion of larvae from raw freshwater fish. Caviar is prepared from fish.

·        Echinococcus granulosus causes Echinococcosis. It is composed of a scolex and only 3 proglottids, making it one of the smallest tapeworms. The scolex has a circle of hooks and 4 suckers similar to Taenia solium. Dogs are the most important definitive hosts. The intermediate hosts are usually sheep. Humans are almost always dead-end intermediate hosts. Transmission: ingestion of eggs from dog faeces. Disease – hydatid cysts in liver causing anaphylaxis if antigens released.

·        Taeniasis: there are two important human pathogens in the genus Taenia: T. solium (pork tapeworm) and T. saginata (beef tapeworm)

·        Trichiniasis (Trichinosis) is caused by Trichinella spiralis (nematode- roundworm). Transmission: fecal-oral; undercooked meat (especially pork). A few days after eating undercooked meat, usually pork, the patient experiences diarrhea followed by 1-2weeks later by fever, muscle pain, periorbital edema and eosinophilia.

·        Ascaridiasis (Ascariasis) caused by Ascaris lumbricoides (giant roundworm). The major damage occurs during larval immigration rather than from the presence of the adult worm in the intestines. The principal sites of tissue reaction are the lungs, where inflammation with an eosinophilic exudates occurs in response to larval antigens. Ascaris pneumonia with fever, cough and eosinophilia can occur with a heavy larval burden.

Explanation

Adaptation is the decline in discharge of sensory impulses when a receptor is stimulated continuously with constant strength. It is also called sensory adaptation or desensitization. The ring has stimulated the receptors continuously with a constant strength for a long time and the receptors adapt.

Explanation

Ligamentum flava resides between the vertebral arches and consist of yellow elastic tissue. The clefts between the vertebral arches are covered by the ligamentum flava, which is the widest in the lumbar region. Therefore, these regions are used for the punctures of the vertebral canal to access the subarachnoid space. This procedure is actually performed on the L2 and L3 as well between the L3 and L4. Moreover, the puncture is also performed between the occipital bone and the first cervical vertebra piercing the atlanto-occipital membrane. In the thoracic region, the spinous processes overlap each other like a tile covering the arches of the lower vertebrae.

Explanation

 ‘T’ wave is the final  ventricular complex and is a positive wave. It is due to the repolarization of ventricular musculature. Normal duration is 0.2sec; normal amplitude is 0.3mV.

Explanation

        Thiamine (vitamin B₁): thiamine pyrophosphate (TPP) is the biologically active form of the vitamin, formed by the transfer of a pyrophosphate group from ATP to thiamine. Biological role of TPP: it is a component of pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes catalyzing the reactions of oxidative decarboxylation of pyruvate and α-ketoglutarate (kreb’s cycle) i.e. it promotes energy formation from carbohydrates and lipids. It’s also a component of transketolase (pentose phosphate pathway of glucose oxidation) essential for fats and nucleic acids synthesis.

Pyruvate to acetyl CoA + CO₂ reaction

            If pyruvate dehydrogenase cannot function properly due to vitamin B₁ deficiency, then pyruvate will be accumulated in blood because it can’t be broken down.

Explanation

Vit. B₃ (Niacin, PP): coenzyme forms NAD⁺, NADP⁺ is derived from tryptophan. Synthesis requires Vit. B₂ and B₆. Vitamin B₃ (niacin) is very high in fish and meat products.

 Pellagra results in vitamin B3 deficiency. Vit. B3 can also be called pellagra preventing.

Explanation

Mycobacteria are aerobic, acid fast bacilli (rods). They are neither gram +ve nor  gram -ve i.e. they are stained poorly by the dyes used in gram stain. They are virtually the only bacteria that are acid-fast (one exception is Nocardia asteroids, the major cause of Nocardiosis, which is also acid-fast). The term  “acid-fast” refers to an organism’s ability to retain the carbolfuchsin stain despite subsequent treatment with an ethanol-hydrochloric acid mixture. The high lipid content (approx. 60%) of their cell wall makes Mycobacteria acid-fast.The major pathogens are Mycobacterium tuberculosis, the cause of tuberculosis and Myobacterium lepra, the cause of leprosy. M. tuberculosis grows slowly. Its cell wall contains long chain (C₇₈-C₉₀) fatty acids called mycolic acids, which contribute to the organism’s acid-fastness. Ziehl-Neelsen stain is also known as acid-fast stain.

Explanation

The major pathway for catabolism of saturated fatty acids is a mitochondrial pathway called β-oxidation. After a long-chain fatty acid (LCFA) enters a cell, it is converted in the cytosol to its Co-A derivative. Because β-oxidation occurs in the mitochondrial matrix, the fatty acid must be transported across inner mitochondrial membrane which is impermeable to Co-A. therefore, a specialized carrier transports the long chain acyl group from the cytosol into the mitochondrial matrix. This carrier is carnitine and this rate-limiting transport process is called the carnitine shuttle. Since carnitine helps the mitochondria utilize energy, it plays a critical role in reducing the occurrence and impact of obesity. In addition to helping the mitochondria burn fat as energy, carnitine is also vital for removing waste products from mitochondria. Obesity and aging contribute to low carnitine levels, which compromises mitochondrial performance and increases insulin resistance, promoting further obesity and carnitine reduction.

Explanation

For the rash to disappear it shows that the serum antibody injected is specific for the Streptococcal erythogenic toxin, which is a positive result. This shows that the antibody was specific and was able to react with the antigen (Streptococcal erythrogenic toxin), therefore the diagnosis was confirmed.

Explanation

Explanation

Type I (Immediate, Anaphylaxis, Reagin): IgE (immunoglobulin E)-dependent activation of mast cells/basophils, usually accompanied by eosinophilia e.g. urticaria (hives), hay fever, asthma (wheezing), rhinitis and conjunctivitis (stuffy nose and itchy eyes; usually seasonal)

Explanation

Enterobius vermicularis causes pinworm infection (enterobiasis). The life cycle is confined to humans. The infection is acquired by ingesting the worm eggs. Perianal pruritus is the most prominent symptom. Pruritus is thought to be an allergic reaction to the presence of either the adult female or the eggs. Scratching predisposes to secondary bacterial infection. In Laboratory diagnosis, the eggs are recovered from perianal skin by using the scotch tape technique and can be observed microscopically. Unlike those of other intestinal nematodes, these eggs are not found in the stools. There are no means of prevention. It is treated with mebendazole.

Explanation

Wilson’s disease is an inherited disorder characterized by excess of copper in the body tissues. It is also known as progressive hepatolenticular degeneration. This disease develops due to damage of the lenticular nucleus particularly the putamen.

      Pathogenesis: gene mutation - defective hepatocyte transport of copper into bile for excretion. Defective incorporation of copper into ceruloplasmin (binding protein for copper in blood). Unbound copper eventually accumulates in blood. Copper is loosely attached to albumin. Copper deposits in other tissue causing a toxic effect. The gene defect in Wilson’s disease affects a copper transport system that produces a dual defect - decreased incorporation of copper into ceruloplasmin in the liver (ceruloplasmin is decreased) and decreased excretion of copper into bile (intrahepatic copper is increased).

Kayser-Fleischer ring can be seen in the cornea of eye.

Explanation

1.     Paraprotein, myeloma protein, M protein or spike protein is an abnormal immunoglobulin (Ig) fragment or immunoglobulin (Ig) light chain that is produced in excess by an abnormal clonal proliferation of plasma cells, typically in multiple myeloma. Monoclonal free light chains in the serum or urine are called bence jones (BJ) proteins.

Bence jones (BJ) protein: free kappa (κ) or lambda (λ) light chains that are excreted in urine associated with plasma cell malignancies (myeloma) and Waldenstrὄm macroglobulinemia. In myeloma, urinalysis for BJ protein is positive in 60-80% of cases.

Explanation

Angina pectoris (stenocardia) is a characteristic sudden, severe, pressing chest pain radiating to the neck, jaw, back and arms. It is caused by coronary blood flow that is insufficient to meet the oxygen demands of the myocardium leading to ischemia. The imbalance between oxygen delivery and utilization may result during exertion (stress), from a spasm of the vascular smooth muscle or from destruction of blood vessels caused by atherosclerotic lesions. Quick removal of pain after taking nitroglycerin suggests angina pectoris (stenocardia).

Explanation

1.     Paraprotein, myeloma protein, M protein or spike protein is an abnormal immunoglobulin (Ig) fragment or immunoglobulin (Ig) light chain that is produced in excess by an abnormal clonal proliferation of plasma cells, typically in multiple myeloma. Monoclonal free light chains in the serum or urine are called bence jones (BJ) proteins.

Bence jones (BJ) protein: free kappa (κ) or lambda (λ) light chains that are excreted in urine associated with plasma cell malignancies (myeloma) and Waldenstrὄm macroglobulinemia. In myeloma, urinalysis for BJ protein is positive in 60-80% of cases.

Myeloma/Plasmocytoma/Multiple Myeloma

Explanation

Scarlet fever is one of the forms of streptococcal infection. It is an acute infectious disease accompanied by local inflammatory changes mainly in the pharynx and typical generalized rash. A punctuate erythematous rash that is most abundant over the trunk and inner aspects of the arms and legs manifests exanthema. The face is also involved, but usually a small area about the mouth (nasolabial triangle) remains relatively unaffected to produce a circumoral pallor. Primary scarlatinic affect is characterized by catarrhal or necrotic tonsillitis:

·        Catarrhal tonsillitis is manifested by hyperemia of pharynx (flaring pharynx or burning faucet) with involvement of oral cavity and tongue. It presents a strawberry appearance because of the erythematous papillae that project from a gray-coated background. When peeling occurs, the tongue becomes beefy or crimson red and glistening.

·        Necrotic tonsillitis is characterized by coagulative necrosis and ulceration. Microscopically, there is a characteristic acute, edematous, neutrophilic (purulent) inflammatory reaction within the affected tissues, mostly affecting the soft palate, pharynx, auditory tube.

Explanation

Congenital deficiency of homogentisate oxidase (homogentisic acid oxidase) in the degradative pathway of tyrosine to Fumarate → pigment-forming homogentisic acid accumulates (homogentisuria) in tissues. Autosomal recessive. Usually benign. Urine turns black on prolonged exposure to air. May have debilitating arthralgias (homogentisic acid toxic to cartilage).

Explanation

Organ of corti is the receptor organ for hearing. Organ of corti is made up of sensory elements called hair cells and various supporting cells. Cells of organ of corti are: inner and outer hair cells (external and internal receptor cells); external and internal phalangeal cells; external limiting cells (cells of Hensen); cells of Claudius.

Explanation

Trachea → main (primary or large) bronchi → lobar (secondary or median) bronchi → segmental (tertiary or small) bronchi → bronchioles (terminal bronchiole → respiratory bronchiole) → alveoli.

As the bronchi decrease in size because of branching, the cartilage plates become smaller and less numerous. The second change observed in the wall of the intrapulmonary bronchus is the addition of smooth muscle to form a complete circumferential layer. The smooth muscles become an increasingly conspicuous layer as the amount of cartilage diminishes. The muscularis layer is more attenuated and loosely organized in smaller bronchi where it may appear discontinuous because of its spiral course. Since the muscular layer is more in the smaller bronchi, it therefore means that bronchospasm will be more pronounced in the small bronchi.

Explanation

Asphyxia is the condition characterized by combination of hypoxia and hypercapnea due to obstruction of air passage. Effects of asphyxia develop in 3 stages: stage of hyperpnea, convulsions and collapse. Hyperpnea is the first stage of asphyxia. It extends for about 1min. In this stage, breathing becomes deep and rapid. It is due to the powerful stimulation of respiratory centers by excess CO₂ (cyanotic skin and mucous membranes). Hyperpnea is followed by dyspnea and cyanosis. Eyes become more prominent. The aspiration interferes with normal air passage from the alveoli and the expiration becomes difficult producing expiratory dyspnea.

Explanation

Hypokalemia (serum K⁺ <3.5mEq/L), can be caused by gastrointestinal or renal loss, decreased intake etc. Clinical and laboratory findings include: muscle weakness and fatigue (most common complaints); arrhythmia; ECG shows ‘U’ wave; polyuria etc. Muscle weakness (muscle hypotonia, flaccid paralysis and weakened peristaltic activity of the smooth muscles of the bowels).

Explanation

Hyperemia or active hyperemia or arterial hyperemia is the term used for the increased volume of blood in the arterial or arteriolar vessels. It is caused by an increased supply of blood from arterial system. The affected tissue or organ is pink or red in appearance (erythema) and warm to the touch.

     Venous or passive hyperemia also known as congestion; the affected tissue or organ is cold to the touch.

Explanation

     Neostigmine/proserin reversibly inhibits anticholinesterase, an indirect acting cholinergic agonists. It is used symptomatically to treat myasthenia gravis. Proserin does not cause CNS side effects and is not used to overcome toxicity of central acting antimuscarinic agents.

Atropine is an antimuscarinic agent and is used for the treatment of overdoses or intoxication of cholinesterase inhibitor (proserin, physostigmine) and some types of mushroom poisoning (certain mushrooms contain cholinergic substances that block cholinesterases). It also blocks the effects of excess acetylcholine resulting from acetylcholinesterase inhibitors.

Physostigmine and pyridostigmine bromide are acetylcholinesterase inhibitors and will further synergize proserine.

Mesaton is an α-adrenergic agonists (adrenomimetics); Isadrin is a β-adrenergic agonists.

Explanation

Three genera of spirochetes cause human infection:

·        Treponema: causes syphilis and the nonveneral treponematoses. Morphology – thin, tight spirals

·        Borrelia: causes lyme disease and relapsing fever. Morphology – large and loosely coiled

·        Leptospira: causes leptospirosis. Morphology – thin, tight spirals

Leptospira is tightly coiled, fine spirochetes that are not stained with dyes but are seen by darkfield microscopy. Leptospira interrogans is the cause of leptospirosis. Human infection results when leptospira is ingested or pass through mucus membranes or skin. They circulate in the blood and multiply in various organs, producing fever and dysfunction of the liver (jaundice), kidney (uremia), lungs (hemorrhage) and CNS (aseptic meningitis). Leptospira C and S letters.

Explanation

Explanation

       One of the most common complications of thyroidectomy (resection of thyroid gland) is hypoparathyroidism because the parathyroid gland lying behind the thyroid gland capsule can be accidentally removed during the surgery by unskilled surgeons. Accidental removal of the parathyroid gland results in hypoparathyroidism.

Explanation

Acetylsalicyclic acid (Aspirin) is an NSAID. Cycloxygenase, the enzyme which converts arachidonic acid into the endoperoxide precursors of prostaglandin, has at least two different  isoforms: COX-1 & COX-2. COX-1 is primarily expressed in non-inflammatory cells whereas COX-2 is expressed in activated lymphocytes, polymorphonuclear cells and other inflammatory cells. Acetylsalicyclic acid and the older non-selective NSAIDs inhibit both cyclooxygenase isoforms & thereby decrease prostaglandin & thromboxane synthesis (disaggregating effect) throughout the body.

Explanation

Barr body is an inactive X-chromosome. So a boy (XY) with an inactive X-chromosome must have an additional X-chromosome – XXY (Klinefelter’s syndrome). Causes :

* nondisjunction (maternal and paternal nondisjunction in meiosis I)

* Mosaicism: with the karyotype being 46, XY/47, XXY

Manifestations: gynecomastia, female pattern of pubic hair distribution, no facial hair, high voice.

Explanation

Glucocorticoids have immunosuppressive effects, anti-inflammatory effects, anti-shock, anti-allergic and anti-toxic effects. Immunosuppressive effects: glucocorticoids inhibit some of the mechanisms involved in cell-mediated immunologic functions, especially those dependent on lymphocytes. These agents are actively lymphotoxic and are important in the treatment of hematologic cancers. The drugs do not interfere with the development of normal acquired immunity but delay rejection reactions in patients with organ transplants. This immunosuppressive effect makes the patient susceptible to other infectious diseases (e.g. chronic tonsillitis).

Explanation

From the bladder, the peritoneum passes onto the uterus to form the vesico-uterine pouch; its floor neighbors the cervix. Posteriorly, the peritoneum covers both intestinal surface and supravaginal part of cervix reaching the posterior surface of vagina. Passing onto the rectum, the peritoneum forms the rectouterine pouch (pouch of douglas). It is the deepest intraperitoneal space in both the upright and the supine position – blood, pus and other free fluids in the peritoneal cavity pool in the pouch because of its dependent location.

Explanation

The superficial veins of the lower limbs give rise to the great and small saphenous veins (vena saphena magna and parva respectively). They arise from the dorsal and plantar venous networks of foot. The small saphenous vein (vena saphena parva) arises at the lateral aspect of foot. The vein rounds the lateral malleolus and ascends along the posterior surface of leg in between the heads of the gastrocnemius muscle. At the popliteal fossa, the muscle pierces the fascia and joins the popliteal vein.

Great saphenous vein (vena saphena magna) arises from the medial portion of the dorsal venous network of foot and ascends along the medial aspect of the leg and thigh.

Explanation

Explanation

In general, these are signs of both right-sided cardiac insufficiency (nutmeg liver – venous congestion) and left-sided cardiac insufficiency (brown induration of lungs – venous congestion). It is Chronic because the patient has been suffering for a long time. In venous or passive hyperemia or congestion, morphologically, the sectioned surface of lungs is dark brown and the process is named brown induration of the lungs. Spleen – cyanotic induration of the spleen; liver – nutmeg liver.

     Acute heart failure refers to sudden and rapid onset of signs and symptoms of abnormal heart functions. Chronic heart failure is characterized by the symptoms that appear slowly over a period of time and become worst gradually.

The main symptoms of right-sided heart failure are fluid accumulation and swelling (edema) in the feet, ankles, legs, liver and abdomen. Left-sided heart failure leads to fluid accumulation in the lungs, which causes shortness of breath. At first, shortness of breath occurs only during exertion, but as heart failure progresses, it occurs with less and less exertion and eventually occurs even at rest. Moist and dry rales are heard over the lungs.

Explanation

        Antacids are weak bases that react with gastric acid to form water and a salt to diminish gastric acidity. Because pepsin is inactive at a pH greater than 4, antacids also reduce pepsin activity. They can be:

·        CO₂ forming: sodium hydrocarbonate (or carbonate); calcium carbonate

·        Non-forming CO₂: magnesium hydroxide, aluminum hydroxide

Uses: hyperacid gastritis, gastric and duodenal ulcers; poisoning with acids.

Adverse effects: in addition to the potential for systemic alkalosis, sodium hydrocarbonate liberates CO₂ causing belching and flatulence (sensation of stomach swelling); aluminum hydroxide tends to cause constipation, whereas magnesium hydroxide tends to produce diarrhea.

Explanation

Osteoporosis is a common adverse effect of long-term corticosteroid therapy, due to the ability of glucocorticoids (prednisolone) to suppress intestinal Ca²⁺ absorption, inhibit bone formation and decrease sex hormone synthesis. Other adverse effects include peptic ulcer (erosions of stomach mucosa), hypokalemia, emotional disturbances and the classic cushing-like syndrome (i.e. redistribution of body fat, puffy face, increased body hair growth, acne, insomnia and increased appetite) are observed when excess corticosteroids are present. Excess corticosteroid results in decreased corticotrophin (adrenocorticotropic hormone) through the negative feedback mechanism.

Explanation

The adrenal gland (suprarenal gland) has a secretory parenchymal tissue organized into cortical and medullary regions. Adrenal cortex (derived from mesoderm; steroid-secreting portion) and medulla (derived from neural crest; catecholamine-secreting portion). The adrenal cortex is divided into 3 zones on the basis of arrangement of its cells:

* Zona glomerulosa (15%): arranged in closely packed ovoid clusters; secretes aldosterone.

* Zona fasciculata (80%): large and polyhedral; arranged in long straight cords; secretes cortisol.

* Zona reticularis (5-7%): cells are arranged in anastomosing cords separated by fenestrated capillaries; secretes androgens.

Hydrocortisone is a glucocorticoid (cortisol) and an intake of hydrocortisone will decrease endogenous production of cortisol from zona fasciculata of adrenal cortex leading to its atrophy.

Explanation

Because norepinephrine is the neuromediator of adrenergic nerves, it should theoretically stimulate all types of adrenergic receptors. In practice, when the drug is given in therapeutic doses to humans, the α-adrenergic receptor is most affected. Norepinephrine causes a rise in peripheral resistance due to intense vasoconstriction of most vascular beds, including the kidney (α₁ effect). Both systolic and diastolic blood pressures increase. α₁ receptors are present on the postsynaptic membrane of the effector organs and mediate constriction of smooth muscle. NB: norepinephrine (noradrenaline) causes greater vasoconstriction than epinephrine, because it does not induce compensatory vasodilation via β₂ receptors on blood vessels supplying skeletal muscles.

Explanation

Urea is the major disposal form of amino groups derived from amino acids and account for about 90% of the nitrogen-containing components of urine. Formation of carbomoyl phosphate by carbomoyl phosphate synthetase I is driven by cleavage of two molecules of ATP. Ammonia is incorporated into carbamoyl phosphate. Ultimately, the nitrogen atom derived from this ammonia becomes one of the nitrogens of urea. NB: carbamoyl phosphate synthetase II participates in the biosynthesis of pyrimidines. However, when the function of carbomoyl phosphate synthetase I is compromised, blood ammonia levels rise and urea synthesis is disturbed.

Explanation

Dimercaprol (unithiol, British anti-lewisite) is used to chelate mercury, bismuth, arsenic and in combination with edentate calcium disodium to treat lead intoxication. It contains two sulfuhydryl (SH-) groups and forms two bonds with metal ions. Administered intramuscularly.

Mannitol – osmotic diuretic; Nalorphine hydrochloride – antidote, blocks opoid receptors and replace opoids from binding with them. Metamizole: analgesic, non-opoid drug. Calcium chloride – Calcium preparation, coagulant with systemic action.

Explanation

Explanation

         The spleen is about the size of a clenched fist and is the largest lymphatic organ. It is located in the upper left quadrant of the abdominal cavity and has a rich blood supply. Most of the spleen consists of splenic pulp. Splenic pulp is divided into two regions: white and red pulp. White pulp consists of a thick accumulation of lymphocytes surrounding a central artery. Lymphocytes that aggregate around the central artery constitute the periarterial lymphatic sheath (PALS). The red pulp contains large numbers of RBCs that it filters and degrades.

Explanation

Vitamin C (ascorbic acid): found in fruits and vegetables; an antioxidant; also facilitates iron absorption by reducing it to Fe²⁺ state. It is necessary for hydroxylation of proline and lysine in collagen synthesis; necessary for dopamine β-hydroxylase, which converts dopamine to norepinephrine. Deficiency leads to: scurvy – swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, “corkscrew” hair; Weakened immune response.

Type III collagen is found in blood vessels; Type IV collagen is found in basement membrane. Deficiency in Vitamin C disrupts the second stage of collagen synthesis in fibroblasts (hydroxylation of collagen) which results in petechiae, bruising, hemarthrosis.

Vitamin B₂ (riboflavin) deficiency – growth retardation, glossitis, conjunctivitis

Vitamin B₁ (thiamine) deficiency – Beri-Beri (polyneuritis)

Vitamin A (retinol) deficiency – Night blindness

Vitamin B₉ (folic acid) deficiency – macrocytic megaloblastic anemia

Explanation

Autosomal dominant: often due to defects in structural genes. Many generations, both male and female are affected. Found in every generation; no generation is left out (skipped). Parent – child in every generation.

Autosomal recessive is usually seen in some generations (other generations are skipped).

It is sex linked, if only males or only females(X-linked) are affected.

Parents are healthy (i.e. a generation was left out) – recessive

Grandfather – Boy (sex linked)

Explanation

Explanation

         Juxtaglomerular apparatus is formed by 3 different structures:

·        Macula densa: is the end portion of thick ascending segment as it opens into the distal convoluted tubule. It is situated between the afferent and efferent arterioles of the same nephron. It is very close to afferent arteriole. Macula densa is formed by tightly packed cuboidal epithelial cells.

·        Mesangial cells: are situated in the triangular region bound by afferent arteriole, efferent arteriole and macula densa.

·        Juxtaglomerular cells: are specialized smooth muscle cells situated in the wall of afferent arteriole just before it enters the Bowman’s capsule.

Explanation

Nerve signals are transmitted by action potential (AP), which are rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane. During the depolarization stage of an AP, the membrane suddenly becomes permeable to sodium ion (Na⁺), allowing tremendous number of positively charged Na⁺ to diffuse to the interior of the axon. A major function of voltage-gated calcium ion (Ca²⁺) channels is to contribute to the  depolarizing phase on the action potential in some cells. Although the gating of calcium channel is slow (slow channels), in contrast to the fast sodium channels. Therefore, sodium channels play a key role in initiation and conduction of action potentials.

Explanation

When adrenocorticotropic hormone (ACTH) is secreted by the anterior pituitary gland, several other hormones that have similar chemical structures are secreted simultaneously. The reason for this is that the gene that is transcribed to form the RNA molecule that causes ACTH synthesis initially causes the formation of a considerably larger protein, a preprohormone called proopiomelanocortin (POMC), which is the precursor of ACTH (corticotrophin) and several other peptides, including melanocyte-stimulating hormone (melanotropin), β-lipotropin, β-endorphin and a few others.

Explanation

Vitamin K is a fat soluble vitamin together with Vitamin A, D and E i.e. bile acid and fat emulsification is essential for their absorption in the small intestine. in biliary tract obstruction, there is decreased bile acid, which leads to decreased fat emulsification and absorption, therefore resulting in decreased fat soluble vitamins (Vitamin A, D, E, K).

Vitamin K is essential for the formation of various clotting factors in the liver, namely clotting factor II, VII, IX and X; Protein C and S.

Factor II – Prothrombin

Factor VII – Stable factor

Factor IX – Christmas factor

Factor X – Stuart-Prower factor

These factors undergo vitamin K-dependent post-translational modification, whereby a number of their glutamic acid residues are carboxylated to form ɣ-carboxyglutamic acid residues. The ɣ-carboxyglutamyl residues bind calcium ions which are essential for interaction between the coagulation factors and platelet membranes. This oral anticoagulants block epoxide reductase and creation of active form of vitamin K resulting in disturbances in prothrombin and proconvertin synthesis in liver.

Prothrombin time (PT) evaluates the extrinsic coagulation system down to the formation of the fibrin clot. Factors that are evaluated include factor VII, X, V, II, and I. PT is increased when a factor level is 30% - 40% of normal. Vitamin K-dependent factors include factor II, VII, IX and X; protein C and S. vitamin K is activated in the liver by epoxide reductase. Activated vitamin K ɣ-carboxylates each of the vitamin K-dependent factors. Carboxylated factors are now able to bind calcium, which are essential for interaction between the coagulation factors and platelet membranes.

Explanation

Obturation (obstruction, to close) of bile duct – it can be:

* Intrahepatic – blockage of intrahepatic bile ducts

* Extrahepatic – blockage of common bile duct (ductus choledochus).

Findings:

* malabsorption: bile salts do not enter the Small Intestine; no emulsification of fat.

*light coloured stool: due to lack of urobilin (which leads to lack of stercobilin).

*Jaundice (posthepatic, mechanic, obstructive): increased conjugated Bilirubin.

* Steatorrhea

The findings are specific for obstruction of bile duct and bile acid deficiency.

Explanation

Mycobacteria are aerobic, acid fast bacilli (rods). They are neither gram +ve nor  gram -ve i.e. they are stained poorly by the dyes used in gram stain. They are virtually the only bacteria that are acid-fast (one exception is Nocardia asteroids, the major cause of Nocardiosis, which is also acid-fast). The term  “acid-fast” refers to an organism’s ability to retain the carbolfuchsin stain despite subsequent treatment with an ethanol-hydrochloric acid mixture. The high lipid content (approx. 60%) of their cell wall makes Mycobacteria acid-fast.The major pathogens are Mycobacterium tuberculosis, the cause of tuberculosis and Myobacterium lepra, the cause of leprosy. M. tuberculosis grows slowly. Its cell wall contains long chain (C₇₈-C₉₀) fatty acids called mycolic acids, which contribute to the organism’s acid-fastness. Ziehl-Neelsen stain is also known as acid-fast stain.

Explanation

        Lymphoid leukosis is a type of malignant neoplasm characterized by the proliferation of cells native to the lymphoid tissues; that is - lymphocytes, histiocytes and their precursors and derivatives. It is characterized by an enlarged liver due to infiltration of cancerous lymphoid cells. In addition, other abdominal organs are also affected.

Explanation

Presence of excess protein (proteinuria) particularly albumin (albuminuria) in urine indicates renal diseases. Urinary excretion of albumin in a normal healthy adult is about 30mg/day. It exceeds this level in glomerulonephritis. It also increases in fever and severe exercise.

Explanation

          The muscles of the hand are divided into 3 groups: muscles of the thumb (thenar muscles); muscle of the fifth digit (hypothenar eminence) and central palmar muscles. Flexor pollicis longus (long flexor muscle of thumb) resides laterally in the deep layer. It flexes the thumb.  Its tendon passes under the flexor retinaculum onto the palm and inserts into the base of the distal phalanx of the thumb.

Flexor pollicis brevis (short flexor muscle of thumb) and abductor pollicis brevis (short abductor muscle of thumb) attaches to the base of the proximal phalanx of the thumb. Opponens pollicis (opposer muscle of thumb) attaches to the first metacarpal bone. It is the deepest of the thenar muscles. Abductor pollicis (abductor muscle of thumb) inserts into the base of the proximal phalanx of the thumb.

NB: first (I) finger – Thumb

Explanation

        During physical activity all lung volumes tend to increase to meet up with the increased demand. Therefore, the whole respiratory volume is increased – inspiratory reserve volume, expiratory reserve volume, tidal volume; vital capacity includes inspiratory reserve volume, tidal volume and expiratory reserve volume. Total lung capacity is the volume of air present in lungs after a deep (maximal) inspiration.

Explanation

       Starvation decreases protein synthesis because the substrates are not readily available. Decrease in protein synthesis decreases oncotic pressure and thereby increasing glomerular filtration. Net filtration pressure is the balance between hydrostatic pressure (glomerular capillary pressure) and oncotic pressure.

Net filtration pressure = Hydrostatic pressure – Oncotic pressure

Therefore, a decrease in oncotic pressure increases the filtration rate according to the degree of starvation which decreases protein synthesis.

Explanation

       The transfused blood might contain pyrogens or its an incompatible blood that activates the immune system. Pyrogenic cytokines, principally IL-1; IL-6 and TNF-α are released into the bloodstream for transport to the hypothalamus, where they exert their action. These cytokines induce prostaglandin E₂ (PGE₂), which is a metabolite of arachidonic acid. It is hypothesized that when IL- 1β interacts with the endothelial cells of the blood-brain barrier in the capillaries of the organum vasculosum laminae terminalis (OVLT), which is in the third ventricle above the optic chiasm, PGE₂ is released into the hypothalamus. At this point PGE₂ binds to receptors in the hypothalamus to induce increase in the thermostatic set point through the second messenger cAMP. In response to the increase in its thermostatic set point, the hypothalamus initiates shivering and vasoconstriction that raise the body’s core temperature to the new set point and fever is established.

Explanation

       The receptor areas of the vestibular labyrinth are represented with the following structures:

·        Macula of Utricle

·        Macula of Saccule

·        Ampullary crests

The first two detect linear motion, while the ampullary crest detect angular motion. The vestibulocochlear nerve supply these receptors. Both maculae consist of the sensory hair cells covered with jelly-like susbstance. The substance contains the crystals of calcium carbonate called otoliths (vestibular otolith). The utricle and saccule detect linear movement, also contributing to balance. The ampullary crests reside within each membranous ampulla. They also comprise the sensory hair cells covered with the same jelly-like substance called the ampullary cupula. The ampullae is the sensory organ in the semicircular canal that sense angular (rotational) acceleration of the head, thereby regulating balance. NB: carousel is a revolving belt.

Explanation

There are two medically important Bacillus species: Bacillus anthracis and Bacillus cereus. Bacillus anthracis causes anthrax. Human disease occurs in 3 main forms: cutaneous, pulmonary (inhalation) and gastrointestinal. Humans are most often infected cutaneously at the time of trauma to the skin, which allows the spores on animal products such as hides, bristles and wool to enter. Spores can also be inhaled or when contaminated meat is ingested. After being inhaled, the organism moves rapidly to the mediastinal lymph nodes and causes hemorrhagic mediastinitis. Pathogenesis is based on the production of two exotoxins  (Anthrax toxin) – edema factor and lethal factor. Hemorrhagic mediastinitis, septic shock hemorrhagic meningitis and death are severe life-threatening complications. In fatal cases, the organism may affect the spleen, liver, intestines, kidneys, adrenal glands and meninges.

Explanation

Atrioventricular (AV) block is the heart block in which the impulses are not transmitted from atria to ventricles (through AV node) because of defective conductive system. AV block can be 1^st degree, 2^nd degree (Mobitz I and II) and 3^rd degree heart block. In complete or 3^rd degree heart block, the impulses produced by the sinoatrial (SA) node cannot get to the ventricles. Therefore, atrial P waves and ventricular complexes (QRS) are recorded independently of each other; the number of ventricular complexes is usually much smaller than the number of atrial (P) waves (i.e. the number of P waves exceeds the number of QRS complexes). The heart rate in persistent complete heart block may be sufficiently high (40 – 50 beats/min) but the patient may be unaware of the disease for a long time.

Sinoatrial (SA) block is the failure of impulse transmission from SA node to AV node. It is also called sinus block. It is characterized by periodic missing of the heart beat and pulse beat. The ECG shows periodic missing of the heart complex (neither P-wave nor the QRST complex are recorded); the length of diastole doubles.

Explanation

The most common drug used in treating stenocardia is organic nitrates (nitroglycerine). High doses of organic nitrates can cause postural hypotension, facial flushing, tachycardia and headache. Overdose can increase nitrates concentration in blood leading to the formation of methemoglobin with a decreased ability to bind O₂. This results in shortness of breath (respiratory inhibition), cyanosis, mental status changes, fatigue etc.

Explanation

Cushing Syndrome: Etiology

 *INCREASE Cortisol due to a variety of causes (Glucocorticoids).

*Exogenous corticosteroids:  result in DECREASE ACTH (MCC).

*Primary adrenal adenoma, hyperplasia or carcinoma (Cushing’s Syndrome).

 *ACTH-secreting pituitary adenoma (Cushing Disease).

Findings: Hypertension, Weight Gain, Moon Facies, Truncal Obesity, Buffalo Hump, Skin Changes (thinning striae), Osteoporosis, Hyperglycemia (Insulin resistance), Amenorrhea, Immunosuppression.

Explanation

Due to the fact that he has been unemployed for a long time, the man has been stressed. Unemployment can lead to psycho-emotional stress. The main stress organ in the body is the adrenal gland producing stress hormones (cortisol, catecholamines). Therefore, this gland must have been exhausted, if the man has stayed unemployed for a long time.

Explanation

Adrenogenital syndrome results from the hereditary stipulated blockade of cortisol synthesis and amplified formation of androgens from general intermediate products.

Explanation

ToRCHeS infections: Toxoplasma gondii; Rubella; Cytomegalovirus; HIV; Herpes simplex virus-2; Syphilis. These are microbes that may pass from mother to fetus. Transmission is transplacental in most cases or via delivery. Toxoplasma gondii causes toxoplasmosis. It is transmitted from cat faeces or ingestion of undercooked meat. Congenital infection of the fetus occurs only when the mother is infected during pregnancy. Congenital infection can result in abortion, stillbirth or neonatal disease with encephalitis, chorioretinitis and hepatosplenomegaly.

Explanation

The lingual artery arises at the level of posterior horn of the hyoid bone from the external carotid artery. The artery occupies the lingual triangle (of Pirogov) immediately below the hyoglossus muscle. It gives the dorsal lingual branches, deep lingual artery and sublingual artery.

Explanation

        Hyperosmolar coma is clinically defined by the presence of relative insulin deficiency and hyperglycemia (high glucose concentration), usually higher than 33.3mmol/L with associated elevated serum osmolality (>300mosm/kg), dehydration and stupor, progressing to coma if uncorrected, without the presence of ketosis or acidosis.

Hypoglycemic coma → ↓ glucose concentration

Ketonemic coma → ↑ ketone bodies

Lactacidemic coma → ↑ lactic acid

Explanation

Hemolytic anemia: according to the mechanisms of the development, they are divided into 3 groups namely:

·        Erythrocytic membrane structure (membranopathy)

·        Erythrocytic enzyme activity (enzymopathy)

·        Structure or rate of hemoglobin synthesis (hemoglobinopathy)

    Membranopathies are characterized by disorders of protein or lipid components of the erythrocytic membrane structure. Membranopathies caused by the disorders of protein structure includes:

o   Hereditary spherocytosis (Minkowsky-shauffard disease)

o   Hereditary elliptocytosis (ovalocytosis)

o   Hereditary pyropoikilocytosis

o   Hereditary and acquired stomatocytosis

     In addition, the membrane defect leads to a loss of both potassium and water, which produces cellular dehydration and results in erythrocyte damage (electrolytic osmotic).

Explanation

The tunics of veins are not as distinct or well defined as the tunics of arteries. Veins are divided into 3 types:

* Small veins/venules: postcapillary and muscular venules

* Medium veins

* Large veins

Arteries:

·        Large or elastic arteries

·        Medium or muscular arteries

·        Small arteries and arterioles

Muscular venules are distinguished from postcapillary venules by the presence of a tunica media. Postcapillary venules possess an endothelial lining with its basal lamina and pericytes. Postcapillary venules have no true tunica media.

·        Tunica intima: consists of endothelium with its basal lamina

·        Tunica media: smooth muscle cells

·        Tunica adventitia: collagen fibers

A vessel without tunica media, also lack muscular tissue. Muscular artery, arteriole and artery of mixed type all have tunica media. Only capillaries and postcapillary venules lack tunica media.

Also a prominent internal elastic membrane helps to distinguish muscular arteries from elastic arteries and muscular venules.

Explanation

Conduction is a way the body eliminates heat by means of direct contact with another object. Heat is transferred down the temperature gradient (i.e. from the object of higher temperature to the object of lower temperature). Conduction requires contact with another object (Key words:  in water).

Heat Radiation is a way the surface of the human body emits heat to the environment in the form of infrared rays. The amount of heat the body radiates to the environment is proportional to the surface of radiation area and to the difference between the mean values of skin and environment temperature. The surface radiation area is the total surface area of body parts that contact the air. Elimination of heat by radiation increases with a decrease in ambient temperature and decreases with its increase. It is possible to reduce elimination of heat by radiation via reduction of the surface of radiation area (“winding oneself into a ball”). Heat radiation does not require a medium for transfer of heat. (Key words: naked or lightly clothed).

Convection is a way the body eliminates heat by means of transferring heat via moving particles of air or water. To dissipate heat by means of convection, body surface shall be airflowed at a temperature that is lower than the temperature of the skin. At that, air layer contacting with the skin warms up, decreases its density, rises and is replaced by cooler, denser air. By increasing the speed of the air flow (wind, ventilation) heat emission increases significantly as well (forced convection). Convection requires convection current; current of gases or liquids (Key words: air over exposed area of skin).

Evaporation is a way the body dissipates heat to the environment by its evaporation via sweat or evaporation of moisture from the skin and respiratory tract mucous membranes of (“wet” heat loss). Evaporation closely related to relative humidity.

Explanation

Common carotid artery branches to give: external carotid artery and internal carotid artery.

External carotid artery → facial artery → angular artery

Internal carotid artery → ophthalmic artery → dorsal nasal artery

Angular artery is the terminal segment of facial artery which branches within the medial angle of the eye. It anastomoses with the branches of the ophthalmic artery (i.e. the dorsal nasal artery). The two big arteries connected are the external carotid artery and the internal carotid artery.

Explanation

Albumin maintains the oncotic pressure in the blood vessels, it does not go out of the blood vessels. Injection of concentrated solution of albumin will increase the oncotic pressure in the blood vessel thereby causing water to move from the interstitial/intercellular space to the blood vessel (i.e. the capillaries).

    In contrast, glucose can pass through the capillaries into the interstitial/intercellular space but it does not readily enter the cell. Therefore, it increases the oncotic pressure in the interstitial space and cause water to move from the intracellular (inside the cell) space to the interstitial/intercellular space.

Explanation

      Bronchopneumonia (focal pneumonia) is marked by patchy exudative consolidation of lung parenchyma. Bronchopneumonia often is a complication of other disease (complication of stomach cancer). Initially bronchi are affected. Then, inflammation spreads to parenchyma of lungs with accumulation of exudates in the alveoli. Grossly, the lungs show dispersed, elevated, focal areas of palpable consolidation and suppuration. Histological features consist of acute (neutrophilic) suppurative - purulent or mixed exudates filling airspaces and airways, usually around bronchi and bronchioles.

Explanation

Morphologically, meningitis can be: meningococcal nasopharyngitis, meningococcal meningitis, meningococcemia. In meningococcemia, changes on the organs are characterized by generalized damage of microcirculation, skin rash, changes in the joints, vascular membrane of the eyes, adrenal glands and kidneys. Changes in the serous layers of the pericardium are observed. The rash is hemorrhagic, star-like, located mainly on the buttocks, lower extremities, eyelids and scleras. Focal necrosis and hemorrhages or bilateral massive hemorrhages with the development of acute adrenal insufficiency (waterhouse-friderichsen syndrome) are noted in the adrenals. Necrosis of nephrothelium of the tubules (necrotic nephrosis) is observed in the kidneys.

Explanation

Rickets results from insufficiency of vitamin D (calcitriol). Calcitriol is the active form of vitamin D. calcitriol production is dependent on the kidney’s 1-α-hydroxylase which converts 25-OHD₃ to 1,25-(OH)₂D₃ (calcitriol). So in cases of renal lesion, there is lack of 1-α-hydroxylase which leads to a deficiency of calcitriol or impaired synthesis of calcitriol. [Cholecalciferol - Vit D]

Osteoectasia is bowing of the bones, particularly of the legs  (bowed leg).

Explanation

The findings are specific for obstruction of bile duct and bile acid deficiency.

Findings:

* malabsorption: bile salts do not enter the Small Intestine; no emulsification of fat.

*light coloured stool: due to lack of urobilin (which leads to lack of stercobilin).

*Jaundice (posthepatic, mechanic, obstructive): increased conjugated Bilirubin.

* Steatorrhea

Explanation

Hemagglutination tests: many viruses clump red blood cells from one species or another (active hemagglutination). This can be inhibited by antibody specifically directed against the virus (hemagglutination inhibition) and can be used to measure the titer of such antibody. Red blood cells (RBCs) also can absorb many antigens and when mixed with matching antibodies, they will clump (this is known as passive hemagglutination, because the Red cells are passive carriers of the antigen).

Explanation

Prokaryotic operons contain an operator – a segment of DNA that regulates the activity of the structural genes of the operon. If the operator is not bound by a repressor molecule, RNA polymerase passes over the operator and reaches the protein-coding genes which it transcribes to mRNA. If a repressor molecule is bound to the operator, the polymerase is blocked and does not produce mRNA. As long as the repressor is bound to the operator, no transcription and therefore no proteins are made. However, when an inducer molecule is present, it binds to the repressor, causing the repressor to change shape so that it no longer binds the operator. When this happens, the RNA polymerase can proceed with transcription.

Explanation

Minute O₂ uptake – 1000ml

    Minute CO₂ emission – 1000ml

    Respiratory Quotient (RQ) = vCO₂ /vO₂ = 1000/1000(ml) = 1

   Carbohydrate = 1; Fat = 0.7; Protein = 0.8

Explanation

There are two types of roots of spinal nerves:

·        Anterior (ventral, motor) root: it arises from the anterolateral sulcus and contains a set of axons of motor neurons located within the anterior columns; the anterior roots number 31 pairs.

·        Posterior (dorsal, sensory) root: it is a set of central processes of sensory pseudounipolar neurons located within the spinal ganglia; the posterior roots also number 31 pairs. Cutting this root will lead to loss of sensory stimulus.

Explanation

       Quadritubercular bodies/tectal plate is the dorsal portion of the midbrain comprises 4 colliculi – two superior and two inferior. The nuclei of colliculi are responsible for reflexes associated with sudden sound and visual stimuli (auditory and visual orientative reflexes); they also maintain consciousness. The nuclei give rise to the tectospinal tract. Superior colliculi – visual orientative reflex; Inferior colliculi – auditory orientative reflex.

Explanation

       Antidiuretic hormone (vasopressin) is secreted in response to decrease blood volume and increase plasma osmolarity. It binds to receptors on principal cells of collecting ductules causing increase number of aquaporins and increase water reabsorption which leads to decreased diuresis.

↑oncotic (colloid-osmotic) pressure → ↑vasopressin → ↑H₂O reabsorption → Normal osmotic pressure. ↑H₂O reabsorption will balance the excess osmotic pressure.

↓vasopressin → ↓H₂O reabsorption → polyuria

Explanation

Athletes that are exercising intensely for the short periods of time, such as in a sprint race, build up large amounts of lactate in their muscles as the result of anaerobic glycolysis. The “warming down” period of continual movement under aerobic conditions performed by athletes for approximately 15mins after a race increases circulation and removes lactate from the muscles.

Aerobic glycolysis progresses to citric acid cycle from pyruvate. The cycle occurs totally in the mitochondria.

Explanation

Lactate, formed by the action of lactate dehydrogenase (converting pyruvate to lactate) is the final product of anaerobic glycolysis in eukaryotic cells. In organs or cells that are poorly vascularized and/or lack mitochondria, formation of lactate is the major fate of pyruvate as seen in lens, cornea of the eye, kidney medulla, testes, leukocytes and red blood cells.

Explanation

Defects in male genitalia:

Hypospadia: fusion of the urethral folds is incomplete and abnormal openings of the urethra occur along the inferior (undersite) surface of the penis, usually near the glans, along the shaft or near the base of the penis.

Epispadia is a rare abnormality (1/30000 births) in which the urethral meatus is found on the dorsum (superior) surface of the penis.

Explanation

The most important trematodes (flukes) are Schitosoma species (blood flukes). Schistosoma causes Schistosomiasis. Schistosoma mansoni and Schistosoma japonicum affect the GIT, whereas Schistosoma haematobium affects the urinary tract. Schistosoma haematobium’s eggs have a terminal spine (sharp point) and lives in the veins draining the urinary bladder. Schistosoma haematobium is found in Africa and the middle-east. Diagnosis depends on finding the characteristic ova (egg) in faeces or urine.

Explanation

Morphology of dysenteric colitis has 4 stages: catarrhal colitis; fibrinous colitis; ulcer formation (ulcerative colitis); healing of the wound. During the stage of fibrinous colitis, within the course of 24hours, a fibrinosuppurative exudate first patchily, then diffusely covers the mucosa and produces a dirty grayish pseudomembrane, consisting of necrotic mucosa, neutrophils, fibrin and erythrocytes. Sloughed pseudomembrane, together with blood-tinged mucus, comprises the characteristic dysenteric stool.

Explanation

Neutrophilic leukocytosis: increase in neutrophil count. Depending on the proportion between the mature and premature forms of neutrophils, two types of the nuclear shift may be distinguished: to the left, when there is an elevated content of immature forms of neutrophilic granulocytes (myelocytes, metamyelocytes, bands) in the blood; And to the right, when the mature neutrophils with a large number of segments (5 – 6) prevail against a background of younger cells disappearing. The nuclear shift may be subdivided into: regenerative, hyperregenerative, degenerative and regenerative-degenerative shifts.

Regenerative shift develops against a background of mild general leukocytosis, accompanied with elevated content of bands and metamyelocytes (immature forms). This shift results from the reactive leukopoiesis (granulocytopoiesis) activation and is common in suppurative septic processes.

Explanation

     Olfactory receptors are situated in olfactory mucus membrane, which is the modified mucus membrane that lines upper part of nostril (superior nasal concha). Olfactory receptor cell is a bipolar neuron. Dendrite of this neuron is short and it has an expanded end called olfactory rod. From the olfactory rod, about 10-12 cilia arise. These cilia project to the surface of olfactory mucus membrane in the upper part of nostril. Mucus secreted by Bowman glands continuously lines the olfactory mucosa.

Explanation

The Mantoux skin test should be read between 48 and 72hrs after administration. The basis of reading  is the presence or absence of induration, which may be determined by inspection and by palpation. A record should also be made of formation of vesicles, bullae, lymphangitis, ulceration and necrosis at the test site. The formation of vesicles, bullae or necrosis at the test site indicates positive result. A negative mantoux result usually signifies that the individual has never been exposed to Mycobacterium tuberculosis i.e. absence of cell mediated immunity to tuberculin.

Type IV (cell mediated, delayed): antibody-independent T-cell mediated reactions e.g. positive mantoux reaction (tuberculin test), hashimoto’s thyroiditis or transplant rejection etc.

Explanation

        Thiamine (vitamin B₁): thiamine pyrophosphate (TPP) is the biologically active form of the vitamin, formed by the transfer of a pyrophosphate group from ATP to thiamine. Biological role of TPP: it is a component of pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes catalyzing the reactions of oxidative decarboxylation of pyruvate and α-ketoglutarate (kreb’s cycle) i.e. it promotes energy formation from carbohydrates and lipids. It’s also a component of transketolase (pentose phosphate pathway of glucose oxidation) essential for fats and nucleic acids synthesis.

Pyruvate to acetyl CoA + CO₂ reaction

            If pyruvate dehydrogenase cannot function properly due to vitamin B₁ deficiency, then pyruvate will be accumulated in blood because it can’t be broken down.

Explanation

Vitamin B₆ (pyridoxine): converted to pyridoxal phosphate (PLP), a cofactor used in transamination (e.g. in ALT and AST), decarboxylation reactions, glycogen phosphorylase. Synthesis of cystathione, heme, niacin (Vit. B₃), histamine and neurotransmitters including serotonin, epinephrine, norepinephrine, dopamine and GABA. Deficiency produces convulsions, hyperirritability, peripheral neuropathy (deficiency inducible by isoniazid and oral contraceptives), sideroblastic anemia due to impaired hemoglobin synthesis and iron excess.

Explanation

Erythrocyte (RBC) rosetting is a phenomenon seen through a microscope where RBCs are arranged around a central cell to form a cluster that looks like a flower. This formation occurs due to an immunological reaction between an epitope on the central cells surface and a receptor or antibody on a red blood cell. The presence of erythrocyte resetting can be used as a test for T cells. It is used in the identification of T cells where a T cell CD2 surface protein is bound to a sugar based CD58 homologue on the surface of a sheep RBC. Because the CD58 homologue is only present on the surface of sheep RBCs, other species’ RBCs cannot be used in this type of resetting. Therefore, a decrease in the number of cells that form rosettes with sheep’s RBCs indicates a decrease in T-lymphocyte level.

Explanation

Anthracosis also known as Coal workers’ pneumoconiosis or black lung disease; it is caused by lung exposure to coal dust. It is common in coal miners and others who work with coal. Inhaled coal dust progressively builds up in the lungs and is unable to be removed by the body; this leads to inflammation, fibrosis and in worse cases necrosis.

Alveolar macrophages remove inhaled particulate matter from the air spaces and red blood cells (RBCs) from the septum of alveoli. They are unusual in that they function both in the connective tissue of the septum (alveolar wall) and in the air space of the alveolus (surface of alveolar cells). In air spaces they scavenge the surface to remove inhaled particulate matter (e.g. dust, pollen, pathogens), thus giving them one of their alternate names – Dust cells. They also phagocytose infectious organisms such as Mycobacterium tuberculosis. Other macrophages remain in the septal connective tissue, where, filled with accumulated phagocytized material, they may remain for much of an individual’s life. Thus, at autopsy, the lungs of urban dwellers as well as smokers will usually show many alveolar and septal macrophages filled with carbon particles, anthracotic pigment and birefringent needle-like particles of silica.

Explanation

Osteomyelitis is the inflammation of bone caused by pyogenic organisms. Acute osteomyelitis is an infection of the bone of less than two weeks’ duration, which typically spreads hematogenously (acute hematogenous osteomyelitis). A delay in diagnosis may cause growth disturbance, deformity or even death. It typically affects the long bones (femur and tibia are the most commonly affected). Pathogenesis: preexisting focus/exogenous infection → infective embolus enters nutrient artery → trapped in a vessel in metaphysis and blocks the vessel → active hyperemia and polymorphonuclear cell exudates → hyperemia and immobilization causes decalcification proteolytic enzymes destroy bacteria and medullary elements → the debris increase and intramedullary pressure increases → follows paths of least resistance → passes through haversian canal and Volkmann canal → local cortical necrosis → enter subperiosteal space → strips periosteum → perforation of periosteum/reach joint by piercing capsule → enters soft tissue and may drain out.

Explanation

Type I (Immediate, Anaphylaxis, Reagin): IgE (immunoglobulin E)-dependent activation of mast cells/basophils, usually accompanied by eosinophilia e.g. urticaria (hives), hay fever, asthma (wheezing), rhinitis and conjunctivitis (stuffy nose and itchy eyes; usually seasonal)

Explanation

Lingual papillae cover the dorsal surface of the tongue anterior to the sulcus terminalis of the tongue. 4 types:

* Circumvallate papillae: large, dome-shaped structures that reside in the mucosa just anterior to the sulcus terminalis . It divides the tongue into anterior 2/3 and posterior 1/3.  Human tongue has 8-12 of it. It has taste buds.

* Filiform papillae: smallest and most numerous. No taste buds, serve only a mechanical role, distributed over the entire anterior dorsal surface. They are the ones that will be coated since they are numerous and serve mechanical role.

* Fungiform papillae: mushroom shaped, have taste buds

* Foliate papillae: occur on the lateral edge of the tongue.

Taste buds are present on fungiform, foliate and circumvallate papillae.

Explanation

Explanation

Early in male development, mesenchyme separating the seminiferous cords gives rise to leydig (interstitial) cells that produce testosterone to stimulate development of the indifferent primordium into a testis. Leydig cells are large, polygonal, eosinophilic cells that typically contain lipid droplets. Leydig cells differentiate and secrete testosterone during early fetal life. Secretion of testosterone is required during embryonic development, sexual maturation and reproductive function:

·        In the embryo, secretion of testosterone and other androgens is essential for the normal development of the gonads in the male fetus.

·        At puberty, secretion of testosterone is responsible for the initiation of sperm production, accessory sex gland secretion and development of secondary sex characteristics.

·        In the adult, secretion of testosterone is essential for the maintenance of spermatogenesis and of secondary sex characteristics, genital excurrent ducts and accessory sex glands.

Explanation

These manifestations describe Acromegaly. Acromegaly is the disorder characterized by the enlargement, thickening and broadening of bones, particularly in the extremities of the body. It is due to hypersecretion of growth hormone (somatotropic hormone) in adults after the fusion of epiphysis with shaft of the bone. Adults develop acromegaly with increased lateral bone growth (e.g. hands, feet, jaw). No linear growth occurs because the epiphyses are fused; characterized by prominent jaw spacing between the teeth; frontal bossing; macroglossia (large tongue). Growth hormone promotes majorly the growth of cartilages since the bones are fused. Growth of cartilages produces the lateral growth in bones. It also promotes growth of muscle and organs.

Explanation

Amyloidosis is the term used for a group of diseases characterized by extracellular deposition of fibrillar proteinaceous substance called amyloid. Systemic amyloidosis contain amyloid associated (AA) protein. It occurs as a complication of chronic infectious or noninfectious inflammatory conditions associated with tissues destruction such as tuberculosis, bronchiectasis, chronic osteomyelitis, chronic pyelonephritis etc. It is typically distributed in solid abdominal organs like liver, spleen, kidneys and adrenals. Morphologically, the kidneys may be normal-sized, enlarged or terminally contracted due to ischemic effect of narrowing of vascular intima. Cut surface is pale waxy and translucent.

Explanation

Systemic lupus erythematous (SLE, Libman-sacks disease) is the classic prototype of the multisystem disease of autoimmune origin, characterized by a bewildering array of autoantibodies, particularly antinuclear antibodies. It is characterized principally by injury to the skin, joints, kidney, and serosal membranes. Antinuclear antibody is directed against several nuclear antigens and can be grouped into 4 categories:

·        Antibodies to DNA

·        Antibodies to histones

·        Antibodies to nonhistone proteins bound to RNA

·        Antibodies to nuclear antigens.

SLE is a type III hypersensitivity reaction with formation of immune complexes. It can cause diffuse proliferative glomerulonephritis seen under the light microscope as “wire loop” of capillaries and granular under the immunofluorescence microscopy.

Explanation

Eubiotics or probiotics aids the development and repopulation of intestinal microbial flora in the event of diarrhea and during treatment with antibiotics and sulfa drugs. A dietary supplement rich in highly concentrated live active cultures contains select high enzymatic function yeast cultures.

Explanation

Explanation

Sulfonylurea are insulin secretagogues because they promote insulin release from the β-cells of the pancreas. The primary drugs used today are the 2^nd generation drugs – glibenclamide, glipizide, glimepiride etc. These agents are useful in the treatment of patients who have type 2 diabetes mellitus and cannot be managed by diet alone. Metformin is the only currently available biguanide; its classed as an insulin sensitizer. Acarbose – α glucosidase inhibitor. Butamide (tolbutamide) is also a sulfonylurea but is older and glibenclamide is more potent and used much more commonly. Actrapid (soluble insulin) is fast acting but not a sulfonylurea.

Explanation

     Prolactin is responsible for lactogenesis. Prolactin is secreted from anterior pituitary gland. It is necessary for the final preparation of mammary glands for the production and secretion of milk. Lactation means synthesis, secretion and ejection of milk.

Explanation

Metastases of breast cancer is either local or distant. Local metastases is usually to the lymphatic nodes of breast base, axilla, subclavicular, parasternal nodes. Distant metastases are hematogenic ones, 40-50% to the bones, lungs, and liver.

Cancer of any of the following will metastasize locally through:

            Submandibular salivary gland – submandibular nodes

            Thyroid gland – deep anterior cervical nodes

            Stomach – celiac nodes

            Lungs – visceral thoracic lymph nodes

Explanation

The greatest branches of the lumbar plexus are the femoral and obturator nerves; others include the iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, lateral cutaneous nerve and the muscular branches. The iliohypogastric nerve arises from behind the lateral border of the psoas major muscle and runs in between the transverses abdominis and the external oblique muscles. The nerve supplies all abdominal muscles, the skin of hypogastrium and the skin of the gluteal region (its superolateral portion).

Explanation

          The embryonic period or period of organogenesis occurs from the 3^rd-8^th weeks of development. The kidney come from 3 slightly overlapping kidney systems – pronephros, mesonephros and metanephros. Metanephros is the definitive kidney, it appears in the 5^th week. Collecting ducts of the permanent kidney develop from the ureteric bud, the bud dilates forming the primitive renal pelvis. These buds continue to subdivide until 12 or more generations of tubules have formed. The tubules of the second order enlarge and absorb those of the 3^rd and 4^th generations, forming the minor calyces of the renal pelvis. During further development, collecting tubules of the 5^th and successive generations elongate considerably and converge on the minor calyx, forming the renal pyramid. The ureteric bud gives rise to the ureter, the renal pelvis, major and minor calyces.

Explanation

Explanation

K⁺ sparing diuretics:

  - aldosterone antagonist: spironolactone, eplerenone

  - inhibit Na⁺ reabsorption: triamterene

The answer is Spironolactone because after the administration of cardiotonics and a thiazide diuretic, if the edema still persists, it is probably due to an increased action of aldosterone on the principal cells in collecting tubule of the kidney. In this case, an aldosterone antagonist will enhance the diuretic effect to prevent the occurrence of ascites. Blocking aldosterone effect prevent further reabsorption of Na⁺ and H₂O which will definitely enhance the diuretic effect. Aldosterone acts on mineralocorticoid receptor → mRNA → protein synthesis (synthesis of Na⁺ channels). Spironolactone prevents/blocks the synthesis of Na⁺ channels.

Explanation

Erosion of the cervix is a defect in the epithelium covering the vaginal portion of the cervix. It is usually caused by inflammation of the mucous membrane of the cervical canal or less frequently, of the vagina. Irritation by cervical leucorrhea results in maceration and scaling of the epithelium with the formation of small superficial ulcers, bright red in colour that bleed when touched – True erosion. 7 – 10days later, columnar (cylindrical) epithelium growing out of the cervical canal gradually covers the ulcerous surface; the resulting “pseudoerosion” may persist with recurrences for many years.

Explanation

The word Ichthyosis comes from the Greek word for a fish. It is applied to disorders that share, as their main feature, a dry rough skin with marked scaling but no inflammation. Because these disorders manifest as abnormal differentiation of the epidermis, the term disorders of cornification is preferred to Ichthyosis. Histologically, there is moderate degree of compact eosinophilic orthokeratosis (hyperkeratosis without parakeratosis). The granular layer is reduced or absent (atrophy of the granular epidermis layer) and keratohyalin granules may appear spongy or fragmented on electron microscopy. The spinous layer is of normal thickness. Filaggrin is reduced in involved epidermis and profilaggrin mRNA is unstable in keratinocytes. This is a retention hyperkeratosis, with a normal rate of epidermal turnover. The differential diagnosis includes X-linked Ichthyosis and acquired Ichthyosis.

Explanation

Rhodopsin or visual purple is the photosensitive pigment of rod cells. It is made up of a protein called opsin and a chromophore. Opsin present in rhodopsin is known as scotopsin. Chromophore is a chemical substance that develops colour in the cell. Chromophore present in the rod cells is called retinal. Retinal is the aldehyde of vitamin A or retinol. Vitamin A is the name given to a group of related compounds that include retinol (vitamin A alcohol); retinal (vitamin A aldehyde) and retinoic acid (vitamin A acid). Rod cells are responsible for dim light vision or night vision or scotopic vision.

Impairment of twilight vision is a defective function of rod cells. Therefore, vitamin A is recommended as the first choice.

Explanation

The nonsteroidal anti-inflammatory drugs (NSAIDs) are a group of chemically dissimilar agents that differ in their antipyretic, analgesic and anti-inflammatory activities. They act primarily by inhibiting the cyclooxygenase (COX 1 and 2) enzymes that catalyze the first step in prostanoid biosynthesis. This leads to decrease prostaglandin synthesis with both beneficial and unwanted effects. Aspirin is one of the most important NSAID. Its most common side effect is its gastrointestinal (GI) effect. Normally, prostacyclin (PGI₂) inhibits gastric acid secretion, whereas PGE₂ and PGF_2α stimulate synthesis of protective mucus in both the stomach and small intestine.

Celecoxib is a selective cyclooxygenase 2 (COX-2) inhibitor. Approved for treatment of rheumatoid arthritis, osteoarthritis, acute to moderate pain, also approved for patients with peptic ulcers or gastroduodenitis. This is due to the fact that only COX 1 is responsible for the gastrointestinal protective functions.

Explanation

Norepinephrine (noradrenaline), epinephrine (adrenaline) and dopamine are catecholamines produced in chromaffin cells of adrenal medulla from tyrosine. The catecholamines are inactivated by oxidative deamination catalyzed by monoamine oxidase (MAO) and by O-methylation carried out by Catechol-O-methyltransferase. The metabolic products of these reactions are excreted in the urine as vanillymandelic acid from epinephrine and norepinephrine; and homovanillic acid from dopamine.

Explanation

Hemolytic/Prehepatic Jaundice is the type of Jaundice that occurs because of excessive destruction of RBCs resulting in ↑ blood level of free, Indirect, unconjugated bilirubin. In this condition, the excretory function of the liver is normal. But the quantity of bilirubin ↑ enormously. The liver cells cannot excrete that much excess bilirubin rapidly. Formation of Urobilinogen (stercobilin) ↑ resulting in the excretion of more amount of stercobilin in stool and urine.

·       Gilbert syndrome (familial nonhemolytic Jaundice): Autosomal recessive defect. Impaired UGT activity. Jaundice occurs with fasting, volume depletion, stress, menses.

·

Explanation

Acute appendicitis is the most common acute abdominal condition requiring surgery. Clinico-morphological classification of acute appendicitis includes:

·        Simple appendicitis

·        Superficial appendicitis

·        Destructive forms: phlegmonous appendicitis; phlegmonous-ulcerative appendicitis; apostematous appendicitis and gangrenous appendicitis.

Acute phlegmonous appendicitis occurs with diffuse infiltration of leukocytes (especially neutrophils) in the wall of appendix. Gross appearance: appendix is increased, swollen, tense and markedly congested and covered by fibrinous exudates (yellowish-green films).

Explanation

Karakurt spider: the word kara meaning “black” and kurt meaning “worm” comes from the Turkic languages. It is black in colour and is identified by the thirteen (13) spots which are found on its dorsal abdomen. These spots are usually red in colour, but may also be yellow, or orange. The female has a body length of 1 – 2cm (10-20mm), while the male is smaller and reaches 0.5 – 0.8cm (5-8mm) at best. Only the female spider’s bite is dangerous (either for humans or cattle) as the male cannot penetrate the relatively thick epidermis.

Explanation

Pirogov’s stages of shock

* Erectile phase: is characterized by strong motor agitation, sweating, tremor of skeletal muscles, staggering gait, frequent urination, transient increase in blood pressure, heart rate and breath rate increases, body temperature also. Painful impulses reach CNS.

* Torpid phase: decompensation in CNS leads to deep oppression. Patient is motionless, does not answer questions or answers very silently and with long time of delay, reflexes are lowered or absent.

Explanation

Neutrophilic leukocytosis: increase in neutrophil count. Depending on the proportion between the mature and premature forms of neutrophils, two types of the nuclear shift may be distinguished: to the left, when there is an elevated content of immature forms of neutrophilic granulocytes (myelocytes, metamyelocytes, bands) in the blood; And to the right, when the mature neutrophils with a large number of segments (5 – 6) prevail against a background of younger cells disappearing. The nuclear shift may be subdivided into: regenerative, hyperregenerative, degenerative and regenerative-degenerative shifts.

Regenerative shift develops against a background of mild general leukocytosis, accompanied with elevated content of bands and metamyelocytes (immature forms). This shift results from the reactive leukopoiesis (granulocytopoiesis) activation and is common in suppurative septic processes.

Neutrophils: Stab (band): 1-6%             (8%)↑

                     Segmented: 47-72%         (59%) normal

                     Myelocyte and Metamyelocyte: 0-1%      Juvenile forms (2%)↑

Since there is an elevated content of immature forms of neutrophils, then it is a regenerative left shift.

Explanation

* Triceps brachii is the chief extensor of the forearm at the humeroulnar joint. Has a long, lateral, and medial head. Inserts on olecranon of ulna bone.

*Infraspinatus muscle: Lateral (external) rotation of the humerus at the glenohumeral joint, also assists in holding the head of the humerus in the glenoid fossa.

*Teres Major muscle: Adduction & medial rotation of the humerus at the glenohumeral joint shoulder joint)

*Subscapularis muscle: Medial (internal ) rotation and adduction of the humerus at the glenohumeral joint, also assists in holding the head of the humerus in the glenoid fossa.

*Levator scapulae muscle: Elevates the scapula.

Explanation

Explanation

The embryonic period or period of organogenesis occurs from the third – eighth weeks of development and is the time when each of the 3 germ layers: ectoderm, mesoderm and endoderm, give rise to a number of specific tissues and organs.

Explanation

Vitamin B6 is a cofactor for decarboxylation reactions.       

Certain amino acids undergo decarboxylation that means the removal of their α-carboxyl group resulting in liberation of CO₂ and formation of biogenic amines. Biogenic amines are physiologically active substances such as hormones, neurotransmitters etc. decarboxylation of amino acids:

·        Tryptophan → Niacin → NAD⁺/NADP⁺

Tryptophan → Serotonin →Melatonin

·        Histidine → Histamine

·        Glutamine → GABA

Glutamine → Glutathione

Explanation

        Muscle spindle s a spindle shaped proprioceptor situated in the skeletal muscle. It is formed by modified skeletal muscle fibers called intrafusal muscle fibers. Muscle spindle gives response to change in the length of the muscle. It detects how much the muscle is being stretched and sends this information to the CNS via sensory nerve fibers. Stimulation of muscle spindle elicits the stretch reflex. Extensor muscles, particularly the antigravity muscles exhibit a severe and prolonged contraction during stretch reflex. Stretch reflex is the reflex contraction of muscle when it is stretched. Also called myotatic or a monosynaptic reflex. It is the quickest of all the reflexes.

Explanation

Atrioventricular (AV) node serves as the gateway for conduction of impulses from the atria to the ventricle. Stimulation of the parasympathetic nerves to the heart (vagus nerve) causes the neurotransmitter acetylcholine to be released at the vagal endings. This neurotransmitter has two major effects on the heart. First, it decreases the rate of rhythm of the sinus node, and second, it decreases the excitability of the AV junctional fibers between the atrial musculature and the AV node, thereby slowing transmission of the cardiac impulse into the ventricles. In the AV node, a state of hyperpolarization caused by vagal stimulation makes it difficult for the small atrial fibers entering the node to generate enough electricity to excite the nodal fibers. A moderate decrease simply delays conduction of the impulse, but a large decrease blocks conduction entirely.

Explanation

Loa Loa filariasis also known as loiasis or African eyeworm. Humans are infected by the bite of the deer fly (mango fly), chrysops, which deposits infective larvae on the skin. The larvae enter the wound, wander in the body and develop into adults. The females release microfilariae that enter the blood, particularly during the day. There is no inflammatory response to the microfilariae or adults, but a hypersensitivity reaction causes transient, localized, nonerythematous, subcutaneous edema (calabar swellings). The most dramatic finding is an adult worm crawling across the conjunctiva of the eye, a harmless but disconcerting event. The disease is found only in tropical central and west Africa, the habitat of the vector Chrysops.

Explanation

Vitamin K is essential for the formation of various clotting factors in the liver, namely clotting factor II, VII, IX and X; Protein C and S.

Factor II – Prothrombin

Factor VII – Stable factor

Factor IX – Christmas factor

Factor X – Stuart-Prower factor

These factors undergo vitamin K-dependent post-translational modification, whereby a number of their glutamic acid residues are carboxylated to form ɣ-carboxyglutamic acid residues. The ɣ-carboxyglutamyl residues bind calcium ions which are essential for interaction between the coagulation factors and platelet membranes. This oral anticoagulants block epoxide reductase and creation of active form of vitamin K resulting in disturbances in prothrombin and proconvertin synthesis in liver.

Explanation

From horizontal (lying position) to vertical (standing position) will make all blood flow towards the lower extremities, thereby reducing venous return (blood going upwards towards the heart) in the first place. This will definitely ↓ cardiac output (C.O) → ↓blood supply to brain (this can lead to fainting). Then there is reflex vasoconstriction to increase venous return to heart, in the absence of any pathology.

Explanation

Somatic cell division is a cyclic process divided into two phases: mitosis (M phase) and interphase. Three other phases, Gap 1 (G₁); synthesis phase (S) and Gap 2 (G₂) further subdivide interphase. M phase is followed by G₁.

M phase: karyokinesis – division of the nucleus into two daughter nuclei.

                  Cytokinesis – division of the cell into two daughter cells.

G₁: a period in which no DNA synthesis occurs.

Period of cell growth S or DNA synthesis phase follows G₁ phase. The DNA of the cell is doubled. The S phase is followed by a period in which no DNA synthesis occurs, a second gap or G₂ phase. A cell that leaves the cycle in G₁ phase to begin “terminal” differentiation enters the G₀ phase, (“O” stands for “outside” the cycle).

Explanation

The usual cause of shock is a decreased cardiac output, which may be due to: heart failure (cardiogenic shock); or too little venous return. The reasons for too little venous return are; reduction in blood volume following the loss of blood or the loss of fluid (in connection with burns, severe vomiting) or peripheral vasodilation and hence too much blood in the periphery. All these leads to a decrease in blood pressure.

        ↓blood volume → vasoconstriction → disturbance of tissue metabolism → vessel damage → ↑vasodilatation and filtration into interstitium → ↓blood volume → ↓blood pressure → O₂ deficiency and acidosis → damage of myocardium → ↓cardiac output → ↓blood pressure → ↓blood supply to kidney → ↓diuresis.

Explanation

Explanation

Hemophilia is a group of sex-linked inherited blood disorders characterized by prolonged clotting time. However, the bleeding time is normal. Usually, it affects the males, with the females being the carriers. Hemophilia occurs due to lack of formation of prothrombin activator. That is why the coagulation time is prolonged. The formation of prothrombin activator is affected due to the deficiency of factors VIII, IX or XI.

   Types of hemophilia: 

*Hemophilia A or classic hemophilia - deficiency of factor VIII (X-LINKED RECESSIVE)

*Hemophilia B or Christmas disease - deficiency of factor IX (X-LINKED RECESSIVE)

*Hemophilia C or factor XI deficiency (AUTOSOMAL RECESSIVE)

It will be passed to the sons – the mother is the carrier.

Explanation

        Apraxia is defined as a cognitive motor disorder in which the patient loses the ability to accurately perform learned, skilled actions. Apraxia is primarily a condition that localized to the dominant (usually left) hemisphere of the brain. In particular, lesions of supramarginal gyrus and underlying white matter of the left parietal lobe have been implicated to cause apraxia.

Explanation

Atherosclerosis is a multifactorial disease that affects the intima of elastic arteries. The disease is characterized by intramural deposits of lipids, proliferation of vascular smooth muscle cells and fibroblasts and accumulation of macrophages. The risk is correlated with elevated low density lipoprotein (LDL), formed from the catabolism of very low density lipoprotein (VLDL) to a cholesterol ester-protein core that carries some 70% of the total serum cholesterol. Atheroma is specifically associated with high blood LDL levels (as well as total cholesterol levels). Risks is inversely related to the HDL levels, perhaps because high density lipoprotein (HDL) helps clear cholesterol from vessels.

HDL – Good cholesterol

LDL – Bad cholesterol

Explanation

Levodopa is a metabolic precursor of dopamine. It restores dopaminergic neurotransmission in the corpus striatum by enhancing the synthesis of dopamine in the surviving neurons of the substantia nigra. Parkinsonism results from insufficient dopamine in specific regions of the brain, attempts have now been made to replenish the dopamine deficiency. Dopamine itself does not cross the blood-brain barrier, but its immediate precursor (levodopa) is actively transported into the CNS and is converted to dopamine in the brain.

Explanation

β₁-adrenoblocker (cardioselective) – Metoprolol: blocks β₁-adrenoreceptors of the heart. Atropine sulphate - M cholinoblocker; Morphine hydrochloride – Narcotic analgesic; Oxytocin - Pituitary hormone (female sex hormone); Furosemide - Loop diuretic

Explanation

Barr body is an inactive X-chromosome. A normal female has one barr body XX, a normal male has no barr body XY.

Trisomy X – XXX (only one X is active in a female; therefore, 2 barr bodies)

Klinefelter – XXY (one barr body)

Turner’s – XO (no barr body)

Edward and Patau involves autosomal chromosomes and not sex chromosomes.

Explanation

Muscarinic receptors belong to the class of G protein-coupled receptors. These receptors, in addition to binding Acetylcholine, it also recognizes muscarine – an alkaloid that is present in certain poisonous mushrooms. Muscarinic effects include miosis, spasm of accommodation, increasing of lacrimal, salivary, gastrointestinal, bronchial and sweat glands secretion, increase of smooth muscle tonus of internal organs, bradycardia, decreased arterial pressure.

Therefore, a block of this receptor will produce opposite effects as listed in the question (e.g mydriatic pupils, dryness of oral mucous membrane)

Explanation

       Lactase (β-galactosidase) cleaves lactose (in milk) producing galactose and glucose. Hereditary deficiencies of lactase have been reported in infants and children with dissacharide intolerance. Treatment for this disorder is to reduce consumption of milk. This is seen when the milk is substituted by glucose solution.

Explanation

Muscarinic receptors belong to the parasympathetic system. Muscarinic effects include miosis, spasm of accommodation, increasing of lacrimal, salivary, gastrointestinal, bronchial and sweat glands secretion, increase of smooth muscle tonus of internal organs, bradycardia, decreased arterial pressure.

Block of M-cholinoreceptor or activation sympathetic nervous system will produce the opposite effects as described in the question (mydriatic pupils - opposite to miosis; dry mouth - opposite to increase salivation)

Explanation

Dithylinum is a neuromuscular blocking drug (myorelaxants). It attaches to the N-cholinoreceptor depolarizing the junction and providing a constant stimulation of the receptor. The continued binding of the depolarizing agent renders the receptor incapable of transmitting further impulses. They are used to relax muscles during surgery.

Explanation

Acetylcysteine is a synthetic mucolytic (expectorant). It has sulfhydryl group that tear disulfide connections, helps mucosa expelling and reduces the viscosity of mucus. Besides this acetylcysteine is an antioxidant and cardioprotector. It increases bronchial secretion or reduce its viscosity (sputum thinning), facilitating its removal by coughing, they are believed to “loosen” cough which becomes less tiring and more productive.

Explanation

       Massive burns leads to hypovolemia and decreases general blood volume in circulation. This decrease in blood volume, decrease perfusion to all organs in the body. Decrease in renal perfusion (renal blood flow) will decrease glomerular filtration rate (GFR).

Explanation

Myocarditis is inflammation of the heart myocardium. Microvascular plethora and diffuse stroma infiltration with lymphocytes and histiocytes are indicative of an inflammatory process taking place in the heart. Heart failure, dilated heart cavities are complications of myocarditis.

Explanation

Group A β-hemolytic streptococci (Streptococcus pyogenes) are one of the most important human pathogens. They are the most frequent bacterial cause of pharyngitis and a very common cause of skin infections. They adhere to pharyngeal epithelium via pili covered with lipoteichoic acid and M protein. The mode of spread of the hemolytic streptococcus is complex and dependent on a number of interrelated factors such as the presence of carriers, droplets, droplet nuclei and dust; viability, infectivity and virulence of airborne streptococci; ventilation; ultraviolet radiation; and population density and susceptibility. In general, group A streptococci are spread by contact. Such contact may be direct as the transfer of Streptococci from the nose to the hands to the surgical wound or airborne. Studies have shown that they produce direct epidemic danger.

Explanation

Trapezius is a flat, triangular muscle, whose base is facing the spinous processes of the vertebrae. It resides in the upper part of the back and the occiput. The right and left trapezius muscles together form a trapezoid.

Origin: the external occipital protuberance, the superior nuchal line, the ligamentum nuchae and the spinous processes of vertebrae C₇ - T₁₂.

Insertion: the spine of the scapula, the acromion and the lateral third of the clavicle.

Action: adducts, rotates, elevates and depresses the scapula.

Nuchal region – neck region

Explanation

Infarction is an area of ischemic necrosis within a tissue or an organ, produced by occlusion of either its arterial supply or its venous drainage. Infarction of the lungs: embolism of the pulmonary arteries may produce pulmonary infarction, though not always. The pulmonary infarcts are classically wedge-shaped or cone shaped with base on the pleura (periphery) hemorrhagic, variable in size and most often in the lower lobes. Cut surface is dark purple or red and it may show the blocked vessel near the apex of the infracted area. Old organized and healed pulmonary infarcts appear as retracted fibrous scars. The characteristic feature is coagulative hemorrhagic necrosis of the alveolar walls.

Explanation

Vestibular nuclei receive impulses concerned with muscle tone and posture from vestibular apparatus and cerebellum. Vestibular nuclei in turn convey the impulses to different parts of the body through the anterior and lateral vestibulospinal tracts. Vestibulospinal tracts are concerned with adjustment of position of head and body during angular and linear acceleration; maintenance of muscle tone and posture; position of head and body during acceleration. Therefore, increase transmission of impulse through this tract leads to increase tone. Extensor muscles are also for balance (connected to vestibular apparatus). The inputs from the otolith organs project mainly to the lateral vestibular nucleus, which in turn sends axons in the lateral vestibulospinal tract to the spinal cord. The input from this tract exerts a powerful excitatory influence on the extensor (antigravity) muscles. When hair cells in the otolith organ are activated, signals reach the medial part of the ventral (anterior, motor) horn. By activating the ipsilateral (same side) pool of motor neurons innervating extensor muscles in the trunk and limbs, this pathway mediates balance and the maintenance of upright posture.

Explanation

Explanation

Staphylococcus aureus is a gram positive cocci that appear in clusters. It causes:

·        Inflammatory disease  like skin infections, organ abscesses

·        Toxin mediated disease like the toxic shock syndrome (TSST-1)

·        MRSA (methicillin-resistant Staphylococcus aureus) infection.

Staphylococcus aureus is a β-hemolytic bacteria i.e. they form a clear zone of hemolysis on blood agar. They are catalase and coagulase (plasmocoagulase) positive.

Explanation

Isoniazid is the hydrazide of isonicotinic acid and is a pyridine. Pyridine occurs in many important compounds including  azines and the Vitamins Niacin(B3) and Pyridoxine(B6). Therefore, isoniazid can be interfered with Vit.B3, B6 and even B1 metabolism by competing with them.

Isoniazid is a first line antituberculosis drug that inhibits the synthesis of mycolic acid. Vit B6 is needed for the transformation of tryptophan to Vit.B3. NAD is a coenzyme of Vit B3.

Explanation

In urea or ornithine cycle, the first two reactions leading to the synthesis of urea occur in the mitochondria, whereas the remaining cycle enzymes are located in the cytosol. The first reaction is formation of carbomoyl phosphate and the second reaction is formation of citrulline. Ornithine and citrulline are basic amino acids that participate in the urea cycle. The release of the high energy phosphate of carbomoyl phosphate as inorganic phosphate drives the reaction in the forward direction. The reaction product – Citrulline is transported to the cytosol where it condenses with aspartate to form argininosucinate. Increased concentration of citrulline in urine and blood indicates a defect in ornithine or urea cycle.

Explanation

Explanation

Vikasol (Menadioni natrii bisulfis) is a synthetic water soluble analogue of Vitamin K. it’s a coagulant. It participates in the formation of prothrombin. It promotes normalization of blood clotting. Indications include acute hepatitis, parenchymal and capillary bleeding, obstructive jaundice.

Explanation

Abstinence: apart from drugs that are usually recognized as producing dependence, sudden interruption of therapy with certain other drugs also results in adverse consequences, mostly in the form of worsening of the clinical condition for which the drug was being used e.g. Acute adrenal insufficiency may be precipitated by abrupt cessation of corticosteroid therapy; frequency of seizures may increase on sudden withdrawal of an antiepileptic etc. These manifestations are also due to adaptive changes and can be minimized by gradual withdrawal.

Explanation

All of the benzodiazepines used to treat anxiety (tranquilizers) have some sedative properties and some can produce hypnosis (artificially produced sleep) at higher doses. Their effects have been shown to be mediated by the α₁-GABA_A receptors. Benzodiazepines are the most widely used anxiolytic drugs e.g. Diazepam, lorazepam, nitrazepam, clonazepam etc. They are also used to treat neurosis.

Explanation

Acidosis is the reduction in pH (increase in H⁺ concentration) below normal range. pH is less than 7.35; it is produced by:

·        Increase in partial pressure of CO₂ in the body.

·        Decrease in HCO₃^- concentration.

Alkalosis is the increase in pH (decrease in H⁺ concentration) above normal range. pH is greater than 7.45; it is produced by:

·        Decrease in partial pressure of CO₂ in the body.

·        Increase in HCO₃^- concentration.

Each of these two disorders has respiratory and non-respiratory forms. The non-respiratory form is divided into metabolic and excretory(non-gaseous).

·        Respiratory acidosis is the acidosis that is caused by alveolar hypoventilation e.g. airway obstruction due to bronchitis or lung diseases (pneumonia).

·        Respiratory alkalosis is caused by alveolar hyperventilation e.g. hypoxia in high altitude.

·        Non-respiratory:

-Metabolic acidosis is characterized by excess accumulation of organic acids such as lactic acid, ketoacids and uric acid formed by normal metabolism e.g. in Diabetes mellitus or extreme/prolonged exercise.

-Excretory/Non-gaseous acidosis may develop in impaired renal H⁺ excretion related to increased loss of bicarbonate in urine; diarrhea causes acidosis by the loss of bicarbonate with faeces.

-Excretory/Non-gaseous alkalosis: vomiting (loss of gastric acid), increased metabolism of lactate and citrate (turns into bicarbonate and water), long-term use of thiazides and loop diuretics.

      It is excretory/non-gaseous alkalosis because of the frequent vomiting.

Explanation

         Muscle contraction is classified into 2 types: Isotonic and Isometric.

·        Isotonic contraction: the tension in the muscle remains the same but the length of the muscle fiber is changing (Iso = same; tonic = tension) e.g. simple flexion of arm, where shortening of muscle fibers occurs but the tension does not change.

·        Isometric contraction: the length of muscle fibers remains the same but the tension is increased e.g. pulling any heavy object when the muscles become stiff and strained with increased tension but the length does not change. Holding (but not moving) – length does not change.

Explanation

Medial cutaneous nerve of arm (medial brachial cutaneous nerve) is a branch of brachial plexus from the infraclavicular part. It’s a thin nerve that arises from the medial cord of brachial plexus and supplies the skin of medial area of arm. Medial antebrachial cutaneous nerve supplies the anteromedial area of forearm.

Explanation

Neurinoma or Schwannoma is a benign tumor of peripheral nervous system. It is formed of spinder-like cells with rod-shaped nuclei. The cells and fibers form rhythmical structures. An acoustic neurinoma is a benign tumor that may develop on the hearing and balance nerves (CNVIII vestibulocochlear nerve) near the inner ear. The tumor results from an overproduction of Schwann cells – small sheet-like cells that normally wrap around nerve fibers like onion skin and help support the nerves.

Explanation

        Droperidol is often combined with a potent narcotic analgesic such as fentanyl to produce neuroleptanalgesia. It is used for neuroleptanalgesia because of its quick effect (action), short duration of action, myorelaxant and antihypertensive effects. Droperidol has quick and short effects, produces hypotension and myorelaxantia.

         Fentanyl + Droperidol = Talomonal (neuroleptanalgesia)

Explanation

            Penicillins inhibit the synthesis of bacterial cell walls and are considered bactericidal too. They bind penicillin binding proteins (transpeptidases) and block transpeptidase cross-linking of peptidoglycan in cell wall. They also activate autolytic enzymes. Benzylpenicillin sodium is a short acting penicillin.     

The cephalosporins are β-lactam antibiotics that are closely related both structurally and functionally to the penicillins. Cephalosporins like the penicillns, inhibit bacterial cell wall synthesis and are considered bactericidal against susceptible organisms.

Explanation

Lactate dehydrogenase (LDH) is an enzyme in cardiac cells which can serve as a marker for injured myocardial cells as it leaks out of damaged cell membranes into the bloodstream. It catalyzes the conversion of pyruvate to lactate (a reversible reaction). It has five (5) isoenzymes (isoenzymes catalyze same reaction), but only LDH₁ is found in the myocardium.

LDH₁ – heart, RBCs and brain; LDH₂- reticuloendothelial system; LDH₃- lungs; LDH₄- kidneys, placenta and pancreas; LDH₅- liver and striated muscle.

Explanation

The various cereals used for bread when coarsely ground contain a large proportion of the external envelope of the grains, which is more or less hard and rough; and by its presence in the intestine it stimulates peristalsis through mechanical irritation. For the above reasons, the following articles of diet tend to overcome constipation: coarse Graham bread, Rye bread, Oatmeal, Brown or “wholemeal” bread, Boston brown bread, shredded wheat.

Explanation

Diphtheria bacteria (Corynebacterium diphtheria) is Gram positive, pleomorphic, often club-shaped rods and are arranged in palisades or in V (at an angle) or L-shaped formations. Media used for isolation are Tellurite agar & Lὄffler medium. Lὄffler nutrient medium consists of coagulated serum & nutrient broth. Selective indicator medium containing tellurite are used in selective culturing. K tellurite is used to inhibit the accompanying flora.

Explanation

Myoepithelial cells are contractile cells that embrace the basal aspect of the acinar secretory cells in salivary glands. Myo – Muscle

Explanation

Blood group O(I): no antigens, therefore no agglutination.

Blood group A(II): A antigen, agglutinate with blood group B(III) and O(I).

Blood group B(III): B antigen, agglutinate with blood group A(II) and O(I).

Blood group AB(IV): A and B antigen, agglutinate with all blood groups. No antibody.

Blood group name is determined by the antigen present on RBC, but the patient has an opposite antibody. So whenever, the antibody corresponds to the antigen, there is agglutination. Since O does not have any antigen, no agglutination can occur.

Explanation

Norepinephrine (noradrenaline), epinephrine (adrenaline) and dopamine are catecholamines produced in chromaffin cells of adrenal medulla from tyrosine. The catecholamines are inactivated by oxidative deamination catalyzed by monoamine oxidase (MAO) and by O-methylation carried out by Catechol-O-methyltransferase. The metabolic products of these reactions are excreted in the urine as vanillymandelic acid from epinephrine and norepinephrine; and homovanillic acid from dopamine.

Explanation

Methotrexate is structurally related to folic acid and acts as an antagonist of that vitamin by inhibiting dihydrofolate reductase (in humans), which is the enzyme that converts folic acid to its active coenzyme form, tetrahydrofolic acid. Trimethoprim and pyrimethamine inhibit the same enzyme but in bacteria and protozoa respectively. This decreases dTMP, needed for DNA synthesis.

Explanation

Allochol and cholenzyme are agents of biliary acids and bile (cholesecretics – induce bile secretion). Cholosas is a plant agent (cholesecretics – induce bile secretion). Nicodinum is a synthetic agent (cholesecretics – induce bile secretion). They all stimulate bile formation. Magnesium sulfate is a drug causing gall bladder contraction and relaxation of sphincter of oddi; it promotes bile excretion. It is also a salt laxative acting on all intestine’s secretions. It is a non-absorbable salt that hold water in the intestine by osmosis and distend the bowel, increasing intestinal activity and producing defecation.

Explanation

Anterolateral abdominal wall has 9 regions and 4 quadrants (RUQ, LUQ, RLQ, LLQ)

·        Right lateral abdominal region: Ascending colon (colon ascendens), right kidney, right ureter and loops of small intestine.

·        Umbilical region: Transverse colon (colon transversum), head of pancreas, duodenum (except superior part)

·        Left lateral abdominal region: Descending colon (colon descendens), left kidney, left ureter and loops of small intestine.

·        Left inguinal region: Sigmoid colon (colon sidmoideum), left ureter, left external iliac artery of artery and vein.

·        Right Inguinal region: Caecum, vermiform appendix, right ureter

Explanation

The Ulnar nerve arises from the medial cord of the brachial plexus. It runs along the medial bicipital groove, and proceeds to the ulnar groove situated on the posterior surface of the medial epicondyle of humerus. There the nerve runs covered by fascia and skin only.

Musculocutaneous nerve arises from the lateral cord then traverses the coracobrachialis and appears in between the biceps brachii and the brachialis muscles.

Radial nerve (nervus radialis) arises from the posterior cord of brachial plexus. It passes the radial canal along with deep artery of arm. The nerve quits the canal via its inferior opening (in between the brachialis and the brachioradialis muscle) that leads to the cubital fossa; here at the head of radius, the nerve splits into the superficial and deep branches.

Explanation

The axillary nerve (nervus axillaris) from brachial plexus, is the greatest branch of the short branches of brachial plexus. It arises from the posterior cord and proceeds to the quadrangular/quadrilateral foramen. It supplies the deltoid and teres minor muscles. The axillary nerve and posterior circumflex humeral artery pass through the quadrangular space. Borders of the quadrangular space:

·        Superior: Teres minor

·        Inferior: Teres major

·        Medial: Long head of triceps

·        Lateral: humerus

Explanation

     Desmoid fibroma is a benign connective tissue tumor. It a kind of dense fibroma and characterized by infiltrating growth and relapses. It is composed of banal, “tame-looking” fibroblasts that do not metastasize. More often it is located on the anterior abdominal wall.