practice

Explanation

Microscopically, iron deficiency anemia is characterized by hypochromia (red cells are pale) and smaller than nomal (microcytic); chlorosis (pale-greenish colouration of skin). There is alopecia, koilonychias, atrophies of the tongue and gastric mucosa (atrophic glossitis and atrophic gastritis). Plummer-Vinson triad: hypochromic microcytic anemia, atrophic glossitis and esophageal webs.

B₁₂ –folic acid deficiency: megaloblastic macrocytic anemia

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)

Type I Hypersensitivity reaction (HSR); anaphylactic and atopic: free antigen cross-links IgE on presensitized (i.e. exposed to the antigen before) mast cells and basophils, triggering immediate release of vasoactive amines that act at postcapillary venules (i.e. histamine). Reaction develops rapidly after antigen exposure because of preformed antibody from first exposure. IgE is the main immunoglobulin involved in type I HSR. Type I: uses IgE and IgG₄

Explanation

          Hypothalamus regulates water content of the body by two mechanisms:

·        Thirst mechanism

·        Antidiuretic hormone (ADH) mechanism

      Thirst center is in the lateral nucleus of hypothalamus. There are some osmoreceptors in the areas adjacent to thirst center. When the extracellular fluid volume decreases, the osmolality of extracellular fluid (ECF) is increased. If the osmolarity increases by 1 – 2%, the osmoreceptors are stimulated. Osmoreceptors in turn activate the thirst center and thirst sensation is initiated. Now the person feels thirsty and drinks water.

Explanation

         Balantidium coli causes balantidiasis. It is the only ciliated protozoan that causes human disease i.e. diarrhea. Domestic animals, especially pigs are the main reservoir for the organism and humans are infected after ingesting the cysts in food or water contaminated with animal or human faeces. Diagnosis is made by finding large ciliated trophozoites or large cysts with a characteristic V-shaped nucleus in the stool. The trophozoites excyst in the small intestine, travel to the colon (large intestine) and by burrowing into the wall cause an ulcer similar to that of Entamoeba histolytica.

Explanation

Classic galactossemia: absence of galactose 1-phosphate uridyltransferase. It is an autosomal  recessive disorder. It causes galactosemia and galactosuria, vomiting, diarrhea and jaundice. There is accumulation of galactose 1-phosphate and galacitol in nerve, lens, liver and kidney tissue causes liver damage, severe mental retardation and cataracts.

Also galactokinase deficiency can cause elevation of galactose in blood (galactosemia) and urine (galactosuria). This is a rare autosomal recessive disorder. It causes galacitol accumulation if galactose is present in diet.

Explanation

Hepatic steatosis can occur when humans are deprived of choline.

Choline + Phosphatidic acid → Phosphatidylcholine (lecithin, PC). In the liver PC can also be synthesized from phosphatidylserine (PS) and phosphatidylethanolamine (PE), when free choline levels are low, because it exports significant amounts of PC in bile and as a component of serum lipoproteins (needed for fat metabolism)

PS → PE →→→ PC. 3 methylation reactions between PE and PC. S-adenosylmethionine is the methyl group donor. If choline, phosphatidylcholine or methionine is deficient, there will be abnormal phospholipid synthesis, oxidative damage caused by mitochondrial dysfunction, lipoprotein secretion (remember, if VLDL cannot be secreted it will be accumulated & cause fatty liver degeneration as seen in hepatic steatosis). PC is also a major lipid component of lung surfactant.

Explanation

All these manifestations listed in the question characterize Down's syndrome.

Chromosomal disorders: trisomy 21 (down’s syndrome); trisomy 18 (edward’s syndrome); trisomy 13 (patau’s syndrome); monosomy X (turner’s syndrome-XO); trisomy X (XXX);

normal female (XX); normal male (XY)

Explanation

Delayed - a month

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

Pulmonary embolism is the most common and fatal form of venous thromboembolism in which there is occlusion of pulmonary arterial tree by thromboemboli. Pulmonary emboli are more common in hospitalized or bedridden patients. The majority of emboli arise from the deep veins of the lower extremities; most of the fatal ones arise from the ileofemoral veins. Consequences of thromboembolism include pulmonary infarction in which pyramidal segments (or ‘triangular’ segments) of hemorrhagic infarction are seen at the periphery of the lung. Detachment of thrombi from the thrombophlebitis site in the lower limbs produces a thromboembolus that flows through venous drainage into the large veins draining into the right side of the heart and then to the pulmonary circulation where they embolize.

Explanation

         Fibroblast is the principal cell of connective tissue. Fibroblasts are responsible for the synthesis of collagen, elastic and reticular fibers, and the complex carbohydrates of the ground substance. Ground substance occupies the space between the cells and fibers (intercellular space). Research suggests that a single fibroblast is capable of producing all of the extracellular matrix components.

Explanation

        The process of transcription of a typical gene can be divided into 3 phases: initiation, elongation and termination. The process of transcription begins with the binding of the RNA polymerase holoenzyme to a region of the DNA known as the promoter. RNA polymerase is a multisubunit enzyme that recognizes a nucleotide sequence (the promoter region) at the beginning of a length of DNA that is to be transcribed. RNA polymerase synthesizes mRNA. It makes a complementary RNA copy of the DNA template strand and then recognizes the end of the DNA sequence to be transcribed (the termination region).

Explanation

          Secretin is produced by S cells of mucous membrane in duodenum and jejunum. Secretin stimulates the secretion of watery juice which is rich in bicarbonate ion and high in volume; increase bile secretion and decrease gastric acid secretion.

Cholecystokinin (also called cholecystokinin-pancreozymin) is secreted by I cells in duodenal and jejuna mucosa. It stimulates the secretion of pancreatic juice which is rich in enzyme and low in volume; increase gallbladder contraction; increase sphincter of oddi relaxation; decrease gastric emptying. Therefore, removal of duodenum will decrease cholecystokinin and secretin secretion.

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

Explanation

Normally, protein digestion takes place in the stomach and small intestine. When this process is impaired, the  protein goes to the large intestine undigested and the gut microflora degrades/breaks down protein into ammonia, phenols, indoles and amines which have been shown to exert toxic effects in vitro and in animal models. Human studies have shown that colonic protein metabolism via the gut microflora is responsive to dietary protein as faecal ammonia and urinary phenolic compound concentrations increase in response to increased intake of protein rich foods. 

Explanation

Lipoma is a benign tumor of fatty tissue. It is the most frequent soft tissue tumor, arising in subcutaneous regions at any site but most commonly on the back, shoulder and neck. It may develop in every site where there is fat tissue. Lipomas are encapsulated, usually small yellow node with distinct (clear) borders.

Explanation

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

Microscopic examination of specific granulomas:

* In Rhinoscleroma of nose, the granuloma (scleroma) consists of plasma cells, epitheloid cells, lymphocytes and hyaline sphere. Large macrophages with light cytoplasm containing klebsiella rhinoscleromatis (Mikulicz’s cells), sclerosis and hyalinosis takes place.

* In TB, the granuloma is reffered to as a tubercle and is classically characterized by the presence of central necrosis surrounded by epitheloid cells, lymphocytes, plasma cells and giant langhance cells. In contrast, caseous necrosis is rare in other granulomatous diseases.

* The syphilis granuloma is calle Gumma. Gumma consist of a central area of fibrinoid or caseous necrosis surrounded by mononuclear inflammatory cells, mostly plasma cells, lymphocytes, epitheloid cells and seldom-giant langhance cells. Around gumma forms the granulation tissue and endovasculitis.

* In Tuberculoid Leprosy, the epidermis contains confluent granulomas composed of macrophages, plasma cells and leprous Virchow’s cells – Leprous Virchow’s cells (or Leprous cells) refer to large foamy macrophages within fatty vacuoles containing leprous mycobacterium.

Explanation

     Follicle stimulating hormone and the luteinizing hormone are together called gonadotropic hormones or gonadotropins because of their action on gonads. Products containing a combination of an estrogen and a progestin are the most common type of oral contraceptives. The estrogen provides a negative feedback on the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) by the pituitary gland, thus preventing ovulation. The progestin also inhibits LH release and thickens the cervical mucus, thus hampering the transport of sperm. Oral contraceptives are the drugs taken orally (by mouth) to prevent pregnancy.

Explanation

        Antipseudomonas penicillins: carbenicillin, ticarcillin, piperacillin – these drugs have activity against several gram negative rods, including Pseudomonas, enterobacter and in some cases Klebsiella species. Carbenicillin-disodium is acid-stable and can be administered orally.

Explanation

     Ketotifen and cromolyn sodium are membrane stabilizers. Ketotifen stabilize basophils membranes and possesses antihistamine (antiallergic) and sedative effects.

Explanation

        Latissimus dorsi is a superficial muscle of the back. The latissimus dorsi is a broad and flat muscle which envelopes the lower portion of the back. The upper part of the latissimus dorsi is covered by the trapezius muscle. The latissimus dorsi pulls the arm backward and medially, rotating the shoulder towards the midline; lowers the raised arm. When the arm is fixed, it pulls the trunk towards the arms (as in exercises on the pull up bar or in crawling).

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.

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.

Explanation

       The pharyngeal tonsil (tonsilla pharyngea) is localized in the nasopharynx. It is an aggregation of the lymphoid tissue on the border of the vault and the posterior wall, it is visible through the fauces opening. The tonsil is well developed in children. Excessive growth of the tonsil may result in labored nasal breathing, in such cases removal of the tonsil is indicated.

Explanation

K⁺ sparing diuretics:

  - aldosterone antagonist: spironolactone, eplerenone

The answer is Spironolactone because after the administration of other diuretics, 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

Microscopic examination of specific granulomas:

* In Rhinoscleroma of nose, the granuloma (scleroma) consists of plasma cells, epitheloid cells, lymphocytes and hyaline sphere. Large macrophages with light cytoplasm containing klebsiella rhinoscleromatis (Mikulicz’s cells), sclerosis and hyalinosis takes place.

* In TB, the granuloma is reffered to as a tubercle and is classically characterized by the presence of central necrosis surrounded by epitheloid cells, lymphocytes, plasma cells and giant langhance cells. In contrast, caseous necrosis is rare in other granulomatous diseases.

* The syphilis granuloma is calle Gumma. Gumma consist of a central area of fibrinoid or caseous necrosis surrounded by mononuclear inflammatory cells, mostly plasma cells, lymphocytes, epitheloid cells and seldom-giant langhance cells. Around gumma forms the granulation tissue and endovasculitis.

* In Tuberculoid Leprosy, the epidermis contains confluent granulomas composed of macrophages, plasma cells and leprous Virchow’s cells – Leprous Virchow’s cells (or Leprous cells) refer to large foamy macrophages within fatty vacuoles containing leprous mycobacterium.

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.

Butamin (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

As the name implies, anti-rabies vaccine is used to prevent (prophylaxis) rabies. It can also be used for treatment (curative). Rabies is a viral disease of animals and humans can be infected by animal’s bite (most common – Dog). A dog can be immunized against the disease.

Explanation

           Antigen presenting cells are the special type of cells in the body, which induce the release of antigenic materials from invading organisms and later present these materials to the helper T cells. Types of antigen presenting cells are macrophages (monocytes); dendritic cells and B lymphocytes. Among these cells, macrophages are the major antigen presenting cells. Macrophages are the tissue form of monocytes (monocytes are in blood; when monocytes get out of blood circulation into tissue they become macrophages).

Explanation

Hematocrit is the percentage of cells present in plasma.  Normal hematocrit is approximately 45%. After uterine bleeding, her circulating blood volume is reduced as a result of the bleeding which result in a decrease or reduction in the hematocrit rate.

Explanation

Two membranes divide the spiral canal of cochlea into 3 compartments – vestibular and basilar membrane. Along the basilar membrane are 20,000-30,000 tiny fibers called basilar fibers. Each fiber has different size and shape. Fibers near the oval window (base) are short and stiff (narrowest), while approaching towards helicotrema (apex), the basilar fibers gradually become longer and soft (widest). The motion of the basilar membrane is generally described as a travelling wave. The parameters of the membrane (stiffness, narrow, wide) at a given point along its length determine its characteristic frequency at which it is most sensitive to sound vibrations. High frequency sounds localize near the base of the cochlea (near the round and oval windows), while low frequency sounds localize near the apex (helicotrema); and the middle frequency sounds – middle part of helix.

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 excitable 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

Explanation

Postcentral gyrus (i.e. part of parietal lobe immediately posterior to central sulcus) is concerned with sensory information (touch).

Precentral gyrus (i.e. part of frontal lobe immediately anterior to central sulcus) is concerned with motor information. Occipital lobe: visual cortex. Cerebellum: coordination of movement and postural adjustment. Temporal lobe: superior temporal gyrus – located in temporal lobe immediately below sylvian fissure concerned with auditory stimuli. 

Explanation

MCHC = [Hb (g/L) ÷  Hematocrit] X 100.

Norm: 32.4 – 34.8%

The percentage of poikilocytes (18%) is relatively low and therefore can be considered physiological. Moreso, no pathological condition is recorded in the patient.

Anisocytosis is the presence of differently sized cells e.g. normocytes, microcytes and macrocytes.

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

Explanation

Explanation

Explanation

The pyramidal fasciculus is subdivided into the corticonuclear/corticobulbar fibers and the corticospinal fibers. The fiber of the pyramidal fasciculus passes through the genu and the anterior portion of the internal capsule and descends to the brainstem and the spinal cord. The corticonuclear tract passes through the genu of the internal capsule.  The genu is situated between the anterior and posterior limbs. Lesion in genu causes alteration in motor activities in opposite side due to damage of corticonuclear/corticobulbar fibers.

Explanation

Explanation

The sinoatrial (SA) node is a small strip of modified cardiac muscle, situated in the superior part of lateral wall of right atrium, just below the opening of superior vena cava. The fibers of this node do not have contractile elements. SA node is called the pacemaker because the rate of production of impulse (rhythmicity) is higher in SA node than in other parts. The rate is 60-100/min and higher during tachycardia when stimulated by sympathetic effects. Atrioventricular (AV) node is 40-60/min.

Explanation

Explanation

Explanation

Aldosterone produced in adrenal cortex (zona glomerulosa): causes increased sodium (Na⁺) reabsorption; increased potassium and hydrogen ions (↑K⁺, H⁺) excretion. They increase sodium (↑Na⁺) channel and Na⁺ /K⁺-pump insertion in principal cells of collecting duct; enhances K⁺ and H⁺ excretion by way of principal cell K⁺ channels and α-intercalated cell H⁺ ATPases of collecting duct. Therefore, increase in aldosterone → ↑ K⁺ in urine (excretion) and ↓ Na⁺ in urine (↑ reabsorption); And decreased aldosterone → ↓ K⁺ excretion (↓K⁺ in urine) and ↓ Na⁺  reabsorption (i.e. ↑Na⁺ in urine); same effects on sweats glands too.

Explanation

One of the major setbacks related to continuous, long term steroid (cortisol, prednisolone) treatments are symptoms due to changes in the balance of normal hormone secretion. This typically results from taking doses greater than our body’s natural production. Once we begin to decrease or discontinue the dose, however, withdrawal symptoms may occur. Thus, steroids are typically given for the shortest time possible. Short-term use does not induce steroid withdrawal syndrome. In general, the longer you are on this steroid, the longer it is going to take your body to readjust to functioning without it. If you are on it for longer than 2 weeks, it can affect your adrenal glands ability to produce cortisol leading to adrenal insufficiency.

Explanation

The popliteal artery is a direct continuation of the femoral artery. It occupies the popliteal fossa together with the popliteal vein and supplies all structures below the knee joint. Upon reaching the leg region, the artery enters the cruropopliteal canal and gives off its two terminal branches – the anterior and posterior tibial arteries. Therefore, a tissue ischemia below the knee joint must be as a result of occlusion of the popliteal artery.

Explanation

Exposure of a cell to ultraviolet (UV) light can result in the covalent joining of two adjacent pyrimidines (usually thymine), producing a dimer. These thymine dimers prevent DNA polymerase from replicating the DNA strand beyond the site of dimer formation. First, a UV-specific endonuclease recognizes the dimer an cleaves the damaged strand on both the 5’-side and 3’-side of the dimer. Pyrimidine dimers can be formed in the skin cells of humans exposed to unfiltered sunlight. In the rare genetic disease Xeroderma pigmentosum, the cells cannot repair the damaged DNA because UV-specific endonuclease is defective, resulting in extensive accumulation of mutations and consequently, skin cancers.

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

Epidemic typhus (human body louse) – Rickettsia prowazekii, can remain latent and reactivate months or years in an infected patient, with symptoms similar to or even identical to the original attack of typhus, including a rash that starts centrally and spreads out, sparing palms and soles. This delayed relapse of epidemic typhus – Brill’s disease.

Epidemic typhus - Lice

Explanation

Epidemic typhus (human body louse) – Rickettsia prowazekii, can remain latent and reactivate months or years in an infected patient, with symptoms similar to or even identical to the original attack of typhus, including a rash that starts centrally and spreads out, sparing palms and soles. This delayed relapse of epidemic typhus – Brill’s disease.

Explanation

     The genus Trypanosoma includes 3 major pathogens: Trypanosoma cruzi, Trypanosoma gambiense and Trypanosoma rhodesiense. T. cruzi causes American trypanosomiasis (chagas disease); the reduvid bug (kissing bug or Triatoma) is the vector.

T. gambiense and T. rhodesiense cause sleeping sickness (African trypanosomiasis); the vector for both is the tse-tse fly (Glossina).

Explanation

Lipid malabsorption resulting in increased lipid (including the fat soluble vitamins A, D, E, K and essential fatty acids – linoleic acid) in the faeces (steatorrhea), can be caused by disturbances in lipid intake or digestion and/or absorption. Lack of vitamin A (vision impairment and poor wound healing); lack of linoleic acid (dermatitis).  Lack of vitamin K leads to impairment in blood coagulation because:

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

           Human immunodeficiency virus (HIV): diploid genome (2 molecules of RNA). The 3 structural genes(i.e. proteins coded for by the genes) are:

·        env (gp 120 and gp 41): formed from cleavage of gp 160 to form envelope glycoproteins. gp 120 is for attachment to host CD4+ T cell. gp 41 is for fusion and entry.

·        Gag (p24): capsid protein

·        pol: reverse transcriptase, aspartate protease, integrase.

ELISA/Western blot (immunoblot) tests look for antibodies to the viral proteins listed above.

Reverse transcriptase synthesizes dsDNA (ds-double stranded) from genomic RNA (mRNA); dsDNA integrates into host genome. Virus binds CD4 as well as a coreceptor, either CCR5 on macrophages (early infection) or CXCR4 on I cells (late infection).

·        Homozygous CCR5 mutation – immunity

·        Heterozygous CCR5 mutation – slower course.

Explanation

Free radical oxidation products forming in irradiated tissues of the organisms are called radiotoxins. In the pathogenesis of radiation damage lipid radiotoxins (lipid hydroperoxides, epoxides) are considered to be of great significance. Being intermediate and final products of lipid peroxidation, they accumulate in the cell membranes impairing their barrier functions. Antioxidants block hydroxyl radical recombination into hydrogen peroxide, preventing stable organic hydrogen peroxide compounds from occurring. This is one way in which the body can defend itself from indirect radiation interactions on a cellular level, and is one reason why antioxidants have received so much attention recently as radioprotectors and cancer prevention agents.

Explanation

Embolism is occlusion of a vessel by material travelling in the circulation.

* Fat/Adipose embolism: obstruction of arterioles and capillaries by fat globules constitutes fat embolism. It may occur following severe fracture trauma to bones, inflammation of bones and soft tissues, fatty liver

* Thromboembolism: a detached thrombus or part of thrombus which may arise in the arterial or venous circulation.

* Gas embolism: two main forms of gas embolism are air embolism and decompression sickness. Air embolism is usually due to accidental pumping of air into the venous circulation during intravenous (IV) injection or transfusion ( bubble – air escaped).

Tissue embolism: fragments of tissue.

Explanation

Normal erythrocyte sedimentation rate (ESR): men: 2 – 10mm/h

                                                                                                Women: 2 – 15mm/h

Products of inflammation (e.g. fibrinogen) coat RBCs and cause aggregation. The denser RBC aggregates, fall at a faster rate within a pipette tube. Therefore, an increase in fibrinogen (2x increase) should produce a proportional increase in ESR.

40 – 50mm/h is the only option higher than the normal range.

↑ESR: most anemias, infections, inflammation (e.g. temporal arteritis), cancer (e.g. multiple myeloma), pregnancy, autoimmune disorders (e.g. SLE)

↓ESR: sickle cell anemia (altered shape), polycythemia (↑RBCs “dilute” aggregation factors), microcytosis, hypofibrinogenemia

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

Esophageal atresia results either from spontaneous posterior deviation of the tracheoesophageal septum or from some mechanical factor pushing the dorsal wall of the foregut anteriorly. Atresia of the esophagus prevents normal passage of amniotic fluid into the intestinal tract, resulting in accumulation of excess fluid in the amniotic sac (polyhydramnios). In addition to atresias, the lumen of the esophagus may narrow, producing esophageal stenosis, usually in the lower third. Stenosis may be caused by incomplete recanalization, vascular abnormalities or accidents that compromise blood flow. Occasionally, the esophagus fails to lengthen sufficiently and the stomach is pulled up into the esophageal hiatus through the diaphragm. The result is a congenital hiatal hernia. There is difficulty with feeding; food is regurgitated out of the mouth. Frothing and bubbling around the mouth at birth is seen.

Explanation

The sole longitudinal fold on the mucosa of duodenum which lies on the posteromedial wall of the descending part. It appears as the result of evagination of the bile duct running along the wall. The major duodenal papilla lies at the lower end of the longitudinal fold. On the top of the papilla, there is an opening for bile and pancreatic ducts which delivers pancreatic secretion and bile to duodenal lumen.

Explanation

The nasal cavity opens with the nostrils to exterior and with choanae to the pharynx. The extended portion of the nasal cavity neighbouring to the nostrils is the limen nasi (nasal limen), the portion respective to the ala area separated from the nasal cavity proper with the major alar cartilage projection called the nasal vestibule. The limen nasi (nasal limen) lining is continuous with facial skin and has longer vibrissae that filter air and sweat and sebaceous glands.

Explanation

During cerebellar lesions, there  are disturbances in posture, equilibrium and movements. Disturbances in movements: ataxia, asynergia, asthenia (weak muscle contractions with characteristically rapid onset of muscle fatigue), Dysmetria, Intention tremor, astasia (loss of the capacity for sustained tetanic contractions), nystagmus, rebound phenomenon, dysarthria, adiadochokinesis, atonia (lack or impairment of muscle tone).

Explanation

The manifestations listed in the question are sympathetic effects and a cholinomimetic - cholinergic agonist (a parasympathetic agonist) can reverse these effects.

Proserin (neostigmine) is an indirect acting cholinergic agonist (anticholinesterase). It preserves endogenous acetylcholine which can stimulate a greater number of acetylcholine receptors producing parasympathetic effects that can reverse the sympathetic effects mentioned. 

Explanation

Explanation

     Obturator artery reaches the thigh region via the obturator canal. The artery supplies the adductors of thigh and the hip joint. The hip joint receives blood from the acetabular branch, which passes within the ligament of head of femur. The obturator artery anastomoses with the inferior hypogastric artery via the pubic branch. 

Explanation

Meningococcal meningitis is characterized by hyperemia of pia mater (extremely plethoric), by the end of the 2_nd – 3_rd day the exudate becomes thicker, green-yellow, purulent (yellow-green cap). Dull-serous exudates during the first days of the disease.

Explanation

Procainamide is the amide derivative of local anesthetic agent named procaine (Novocain). Procaine was also found to have antiarrhythmic activity, but is not suitable clinically due to the rapid hydrolysis and marked CNS effects of it. Procainamide also has the anticholinergic effect. Its adverse effects include skin rash, allergic reactions, blurred vision, tremor etc.

Timolol is a non-selective β-adrenergic antagonist (β-adrenoblocker) – they can be used to treat glaucoma because they decrease intraocular pressure through their dilatory action. But the anticholinergic effect of procainamide will cause a further increase in the intraocular pressure in glaucoma.

Glaucoma is increased intraocular pressure.

Phenytoin is a class Ib antiarrhythmic drug that can be used to treat abnormal heart rhythms.

Explanation

Pyrazinamide is a synthetic, orally effective, bactericidal, antitubercular agent used in combination with Isoniazid, rifampin and ethambutol. It is bactericidal to actively dividing organisms, but the mechanism of its action is unknown. Pyrazinamide must be enzymatically hydrolyzed to pyrazinoic acid, which is the active form of the drug. Its toxicity can produce hyperuricemia and hepatotoxicity. Urate retention may precipitate a gouty attack.

Explanation

Precipitation (precipitin): in this test, the antigen is in solution. The antibody cross-links antigen molecules in variable proportions and aggregates (precipitates) form. Precipitin test can be done in solution or in semisolid medium (agar). This reaction can be made quantitative i.e. antigen or antibody can be measured in terms of micrograms of nitrogen present. It is used primarily in research.

Explanation

Indomethacin is a non-steroidal anti-inflammatory drug (NSAID), an inhibitor of COX-1 and COX-2. Cyclooxygenase (COX) converts arachidonic acid into the endoperoxide precursors of prostaglandin. COX-1 is present in non-inflammatory cells (normal body tissues); COX-2 is present in lymphocytes, polymorphonuclear cells and other inflammatory cells. Side effects: GI symptoms – bleeding, ulceration and perforation. Because COX-1 is used to produce mediators that help to protect gastric mucosa, whenever COX inhibitors are used they produce this side effects.

Explanation

Procainamide is the amide derivative of local anesthetic agent named procaine (Novocain). Procaine was also found to have antiarrhythmic activity, but is not suitable clinically due to the rapid hydrolysis and marked CNS effects of it. Procainamide also has the anticholinergic effect. Its adverse effects include skin rash, allergic reactions, blurred vision, tremor etc.

Explanation

Active forms of oxygen (reactive oxygen species) are formed continuously as by-products of aerobic metabolism, through reactions with drugs and environmental toxins, or when the level of antioxidants is diminished, all creating the condition of oxidative stress. One of the protective mechanisms by which the cell minimize the toxic potential of these compounds is by enzymes that catalyze antioxidant reactions. The 3 most important enzymes are glutathione peroxidase, catalase and superoxide dismutase. The superoxide dismutase is specific for converting superoxide to hydrogen peroxide which is then neutralized by catalase or glutathione peroxidase.

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.

Dorsal scapular nerve (nervus dorsalis scapulae) runs to the levator scapulae and the rhomboid muscles.

Subscapular nerve (nervus subscapularis) supplies the subscapularis and the teres major muscle.

Explanation

The dog is conditioned to salivate at the sight of food and flash of light – that is a conditioned reflex that requires learning, memory and recall of previous experience (likewise the student summarizing). The established conditioned reflexes can be inhibited: externally and internally. External inhibition: disturbing factors like a stranger, sudden noise (the bell in the case of a dog and TALKING in the case of the student) or a strong smell can abolish the conditioned reflex and inhibit salivary secretion. This extra stimulus evokes the animal’s curiosity  and distracts the attention. Internal inhibition can be:

*Extinction of conditioned reflex: failure to reinforce the conditioned reflex by unconditioned stimulus.

*Differential: alteration of conditioned stimulus.

Explanation

Tuberculin (Mantoux) skin test: this test is done by intradermal injection of tuberculoprotein (tuberculin), purified protein derivative (PPD). Type IV hypersensitivity reaction.

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.

Explanation

Hepatitis serologic markers:

·        Anti-HAV (IgM): IgM antibody to HAV; best test to detect acute hepatitis A

·        Anti-HAV (IgG): IgG antibody indicates prior HAV infection and/or prior vaccination. This antibody protects against reinfection.

·        HBsAg: Antigen found on surface of HBV; indicates hepatitis B infection.

·        Anti-HBs: Antibody to HBsAg; indicates immunity to hepatitis B.

·        HBcAg: Antigen associated with core of HBV.

·        Anti-HBc: Antibody to HBcAg

·        HBeAg: A second different antigenic determinant in the HBV core. HBeAg indicates active viral replication and therefore high transmissibility.

·        Anti-HBc: Antibody to HBeAg; indicates low transmissibility.

Hepatitis A virus (HAV); Hepatitis B surface antigen (HBsAg); Hepatitis B core antigen (HBcAg); Hepatitis B e antigen (HBeAg).

If anti-HBs indicates immunity to hepatitis B, it therefore means that the patient has previous hepatitis B (i.e. has been infected before).

Explanation

Hormone receptors are situated either in cell membrane or cytoplasm or nucleus of the target cells. Receptors of thyroid hormones and steroid hormones (testosterone, estrogen, progesterone, aldosterone) are in the nucleus of the cell. They execute their function by acting on genes in the target cells. Hormone-receptor complex moves towards the DNA and binds with DNA. This increases transcription of mRNA and therefore synthesis of proteins.

Explanation

Reciprocal inhibition is the inhibition of antagonistic muscles when a group of muscles are activated, an important feature of both flexor and extensor reflexes, as a result of reciprocal innervation. Usually, excitation of  one group of  muscles is associated with the inhibition of another…i.e antagonistic group of muscles on the same side. E.g when a flexor reflex is elicited, the flexor muscles are excited (contracted) and the extensor muscles are inhibited (relaxed) in that side.

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

Increase lactate in blood can result in lactic acidosis, upsetting the fragile buffer system in the body.

Explanation

Sickle cell hemoglobin (HbS) point mutation causes a single amino acid replacement in β chain of hemoglobin (substitution of glutamic acid with valine). Pathogenesis of sickle cell anemia: low O₂, high altitude or acidosis precipitates sickling – modified shape (deoxygenated HbS polymerizes) → anemia and vaso-occlusive disease. Clinical findings include: dizziness, general weakness, fatigue, “crew-cut” on skull X-ray due to marrow expansion from increased erythropoiesis (this is also seen in thalassemia)  etc. Sickle cells are crescent-shaped RBCs.

Explanation

Edema due to increase in hydrostatic pressure – Hydrodynamic

Edema due to decrease in colloid-osmotic (oncotic – protein) pressure – Colloid-osmotic

Edema due to increase in permeability of vessel wall – Membranogenic

Edema due to decrease lymph drainage – Lymphogenic                           

A combination of any of the above mechanisms – Mixed.

Explanation

Collagen, most abundant protein in human body; organizes and strengthens extracellular matrix. Collagen contains Gly-X-Y (X and Y are proline or lysine). Glycine(Gly) makes 1/3 of collagen. Oxyproline (hydroxyproline) is a major collagen amino acid which enables it to be regarded as a marker that reflects the catabolism of collagen.

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.

Explanation

Favus is caused by anthropophilic fungus Trychophyton schoenleini which affects glabrous skin and scalp. Favus is a form of tinea capitis in which crusts are seen on the scalp. Typical (scutular) form: the main element is a scutula being a pure fungus culture in the epidermis. Affected hair is lusterless, atrophic, brittle, lifeless, very much like hair of old uncared wigs.

Explanation

          Due to the positive fibrin reaction and eosinophilia of the collagen fibers, it is better to choose fibrinoid swelling since there is no record of any inflammatory reaction or cells. Fibrinoid swelling changes is a stromal vascular proteinous degeneration. The main signs are revealed microscopically: the bands of collagen fibers are homogenous, impregnated with plasma proteins.

Explanation

Every male child has the Y-chromosome. A Y-linked disease only affects males and a diseased father will pass it to all (100%) his male children. Male sex chromosome (XY)

Explanation

These manifestations points to portal hypertension. Portal hypertension:

Pathogenesis: resistance to intrahepatic blood flow due to intrasinusoidal hypertension. Anastomoses between portal vein (vena porta hepatis) tributaries and the arterial system. Complications: ascites, periumbilical venous collaterals (caput medusa); esophageal varices; congestive splenomegaly; hemorrhoids

↑in blood pressure in portal vein → portal hypertension

Explanation

Explanation

Explanation

Capillaries are the smallest diameter blood vessels, often smaller than the diameter of an erythrocyte. Based on their morphology, 3 types of capillaries are distinguished: continuous, fenestrated and discontinuous (sinusoidal) capillaries. Sinusoidal capillaries are typically found in the liver, spleen and bone marrow. They are bigger in diameter and more irregularly shaped than other capillaries, the basal lamina underlying the endothelium may be partially or even completely absent.

Fenestrated capillaries are found in endocrine glands and sites of fluid and metabolite absorption such as gallbladder and intestinal tract. Continuous capillaries are typically found in muscle, lung and the CNS.

Explanation

Gastrinoma (Zollinger-Ellison syndrome; G-cell tumors): it is a malignant tumor (60 – 90% of cases) that secretes excess gastrin, producing hyperacidity. Parietal cell mass is increased because of hyperplasia from excessive gastrin production. The majority is located in the duodenum (60% of cases) and less commonly in the pancreatic Islet cells (30% of cases). It is characterized by acid hypersecretion (hyperacidity hypersecretion) with diarrhea; epigastric pain with weight loss; maldigestion of food; peptic ulceration; heartburn from gastroesophageal reflux disease (GERD).

Explanation

Uremia is not a single event, but rather a syndrome (a constellation of symptoms) that develops in an individual who has end-stage renal disease. Because the kidney is pivotal in maintaining water, acid-base and electrolyte balance and in removing toxic waste products, the symptoms of uremia are widespread and affect all the organs and tissues of the body. Common symptoms include uremic encephalopathy, hypertension, osteodystrophy with CNS changes, including confusion and psychosis characterizing end stages of renal disease.

Explanation

·        Neuroparalytic arterial hyperemia is caused by damage or blockage of α-adrenoreceptors (sympathetic nervous system). It is characterized by reduction or absence (paralysis) of the sympathetic nervous system effects on the walls of the arteries and arterioles.

·        Neurotonic arterial hyperemia is caused by activation of parasympathetic nervous system; irritation of vascular dilators part of vascular center (CNS) or inhibition of vascular – constrictor part of this center (vasomotor center of CNS); M-cholinoreceptors; H₂-histaminereceptors. It is characterized by predominance of the parasympathetic nervous system effects on arterial vascular walls.

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

Intoxication with drugs leads to:

·        Disturbances in organs and systems functions: neurotoxic, hepatotoxic, nephrotoxic, hematotoxic, ulcerogenous – ulcers formation in GIT.

·        Teratogenic: ability to cause fetal malformation (in the first trimester of pregnancy i.e. till 12 weeks.

·        Embryo and fetotoxic: ability to make a toxic influence on embryo and fetus correspondingly, causing disturbance down to death (after 12 weeks).

·        Mutagenic: ability to impact on a genetic level causing mutations in several generations.

·        Blastogenic: ability to cause neoplasms both benign and malignant (carcinogenic).

 multiple congenital defects - fetal malformations.

Explanation

Explanation

Tetanus is defined as the sustained contraction of muscle due to repeated stimuli with high frequency. When the multiple stimuli are applied at a higher frequency in such a way that the successive stimuli fall during contraction period (period of shortening) of previous twitch, the muscle remains in state of tetanus. While increasing the frequency, fusion of contractions increases every time and finally complete tetanus occurs. Holotetanus – complete tetanus.

When the frequency of stimuli is not sufficient to cause tetanus, the fusion of contractions is not complete and then we have – incomplete/partial/waved tetanus. This occurs (i.e. the next stimuli occurs) during the period of relaxation.

Explanation

Within the first 24hours, the first leukocyte to get into any inflammatory focus are the neutrophils, followed by the monocytes (macrophages) and then lymphocytes.

Neutrophils are the first leukocytes that cross the blood vessel wall to enter inflammatory sites. Under normal conditions, leukocytes are restricted to the center of small blood vessels, where the flow is fastest. In inflammatory sites, where the vessels are dilated, the slower blood flow allows the leukocytes to move out of the center of the blood vessel and interact with the vascular endothelium. Even in the absence of infection, monocytes migrate continuously into the tissues, where they differentiate into macrophages; meanwhile, during an inflammatory response, the induction of adhesion molecules on the endothelial cells, as well as induced changes in the adhesion molecules expressed on leukocytes recruit large numbers of circulating leukocytes, initially Neutrophils and later monocytes, into the site of an infection (inflammatory focus).

First –Neutrophils; second –monocytes and macrophages; third –lymphocytes.

Explanation

Resting membrane potential of a cell is maintained by an active transport of sodium and potassium ions through the membrane i.e. the Na⁺-K⁺ ATPase pump. This pump which uses ATP, actively transports sodium ions to the extracellular space (outside of the cell) and potassium ions in the opposite direction (inside). Note that more positive charges are pumped to the extracellular space than to the intracellular space (3Na⁺ to the extracellular space for each 2K⁺ to the intracellular space), leaving a net deficit of positive ions on the inside; this causes a negative potential inside the cell membrane, which is the resting membrane potential. In the absence of ATP, this pump cannot work and therefore no resting membrane potential is registered.

Explanation

Tocopherol acetate (Vitamin E) consists of 8 naturally occurring tocopherols of which α-tocopherol is the most active. Vitamin E is an antioxidant which prevents the nonenzymatic oxidation of cell components e.g. polyunsaturated fatty acids by molecular oxygen and free radicals. Consumption of foods rich in these antioxidant compounds has been correlated with a reduced risk for certain types of cancers as well as decreased frequency of certain other chronic health problems. Vitamin E is indicated in radiation disease, rheumatoid arthritis, hypovitaminosis, skin and hepatic diseases etc.

Explanation

Explanation

       Intracellular accumulations (parenchymal degeneration or dystrophies). Intracellular fatty degenerations are the abnormal accumulations of triglycerides within parenchymal cells. The liver, heart, kidneys are damaged the most frequently. Fatty degeneration of the heart – Tiger’s heart; fatty degeneration of the liver – Goose liver; fatty degeneration of the kidney – large white kidney.

Explanation

The genus Leishmania includes 4 major pathogens: Leishmania donovani; L. tropica; L. Mexicana and L. braziliensis. Leishmania donovani is the cause of kala-azar (visceral leishmaniasis). In visceral leishmaniasis, the organs of the reticuloendothelial system (liver, spleen and bone marrow) are the most severely affected. It occurs in the Middle East, southern Russia, China, India and Sub-saharan Africa. The lifecycle involves the sandfly as the vector and a variety of mammals such as dogs, foxes and rodents as reservoirs.

Explanation

Explanation

Rest potential of cardiomyocytes is the electrical potential difference (voltage) across the cell membrane (between inside and outside of the cell) under resting condition. It is very important because it determines if the myocardium can respond to impulse and contract to pump blood effectively. The condition of the muscle during resting membrane potential is called the polarized state.

Explanation

Calcium ion concentration in a myocardial cell is needed both for its action potential propagation (this determines rate of heart beat; plateau stage) and muscle contraction (force). Therefore calcium ion determines both the rate and force of heart contraction. A ↓Ca²⁺ → ↓Heart Rate and Force.

Explanation

        Hodgkin’s disease or lymphogranulomatosis is a disorder involving primarily the lymphoid tissue. It is separated from non-hodgkin lymphoma because:

First, it is characterized morphologically by the presence of distinctive neoplastic giant cells called Reed-sternberg’s cells, admixed with a variable inflammatory infiltrate.

Secondly, it is often associated with distinctive clinical features, including systemic manifestations such as fever.

Reed-sternberg cell: classically, it is a large cell, most often binucleate or bilobed, with two halves often appearing as mirror images of each other. Its identification is essential for the histologic diagnosis. The origin of Hodgkin’s lymphoma is unknown.

Explanation

A single accidental exposure to a high dose of radiation during a short period of time is referred to as an acute exposure and may produce biological effects within a short period after exposure. At or above approximately 50rads, acute effects are predictable. 4 periods are distinguished:

·        Initial period (or prodromal phase or primary reaction period): 1 – 2days; begins a few hours after irradiation. Signs include overexcitation of the CNS, increase temperature and lymphopenia.

·        Latent phase: 1 – 2 weeks; only lymphopenia and thrombocytopenia may develop.

·        Manifest phase: hematologic syndrome, CNS and GI syndrome; leukopenia, thrombocytopenia, agranulocytosis (i.e. absence of granulocytes)

·        Recovery phase: gradual restoration of the functions impaired by the sickness.

Explanation

Increased preload causes dilatation and hypertrophy (eccentric hypertrophy – Myogenic dilation) of the ventricular wall. Sarcomeres duplicate in series causing the individual muscle fibers to increase in length and width. Mitral valve or Aortic valve regurgitation is a common cause. Myogenic dilation is characterized with thinning of the ventricular wall and dilation of the left ventricular and atrial cavities.

Explanation

Any nucleotide is composed of a nitrogenous base (purine or pyrimidine), a five-carbon sugar (either ribose or 2-deoxyribose) and phosphate groups.

Major nitrogenous bases:

·        Purine: adenine and guanine

·        Pyrimidine: cytosine, thymine and uracil

Minor nitrogenous bases:

·        Purine: 5-methylcytosine, N⁶methyladenine, N⁷methylguanine

·        Pyrimidine (unusual): methylcytosine present in DNA and dihydrouracil present in tRNA.

Explanation

The sole longitudinal fold on the mucosa of duodenum which lies on the posteromedial wall of the descending part. It appears as the result of evagination of the bile duct running along the wall. The major duodenal papilla lies at the lower end of the longitudinal fold. On the top of the papilla, there is an opening for bile and pancreatic ducts which delivers pancreatic secretion and bile to duodenal lumen (hepatopancreatic ampulla).

Explanation

A peculiar variant of histotoxic (tissue) hypoxia arises during acute dissociation or uncoupling of processes of oxidation and phosphorylation reactions in respiratory chain. The agents that dissociate process of oxidation and phosphorylation are wide range of substances of exogenous and endogenous origin which includes: hormones of thyroid gland, excess calcium, toxins etc. In a healthy organism, thyroid hormones (thyroxine and triiodothyronine) carry out the function of physiologic regulation of the association of oxidation and phosphorylation degree, together with other functions.

Explanation

* Lens: a transparent, crystalline, biconcave structure; suspended from the inner surface of the ciliary body by a ring of radially oriented fibers, the zonule of zinn. Diopter is a unit of measurement of the optical power of a lens or curved mirror.

* Vitreous body: composed of a transparent gel substance that fills the vitreous chamber. It contains hyaluronic acid, widely dispersed collagen fibrils and other proteins and glycoproteins. The fluid component of the vitreous body is called vitreous humor.

* Cornea: anterior window of the eye.

* The cornea is continuous with the sclera. The sclera is composed of dense fibrous connective tissue that provdes attachment for the extrinsic muscles of the eye. It constitutes the “white” of the eye.

* The ciliary body is a ring-like thickening that extends inward just posterior to the level of the corneoscleral junction. Within the ciliary body is the ciliary muscle, a smooth muscle that is responsible for lens accommodation. Contraction of the ciliary muscle changes the shape of the lens, which enables it to bring light rays from different distances to focus on the retina.

Explanation

Acute inflammation has 3 major components: alteration, exudation and proliferation. Alterations in the tissue structure and vascular caliber can lead to injury and increase in blood flow. It is subdivided into primary and secondary.

Secondary alteration is the destruction of cells and tissues by factors which are released and activated in the organism in the primary alteration. These factors are called inflammatory mediators. They can be subdivided into two groups: humoral and cellular mediators.

Explanation

Lobeline hydrochloride is a N-cholinergic agonists (N-cholinomimetics). It stimulates N-cholinoreceptors located in the CNS, carotid glomerulus, sympathetic and parasympathetic ganglia and adrenal medulla. They are used as respiratory stimulants (analeptics with reflex action) in respiratory arrests.

Atropine sulphate: M-cholinergic antagonist (M-cholinoblocker)

Adrenaline hydrochloride: adrenergic agonist (adrenomimetic)

Mesaton: α-adrenergic agonist (α-adrenomimetic)

Pentamin: ganglioblocker

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.

 Neutrophils: Stab (band): 1-6%                        (20%)↑

                                    Segmented: 47-72%         (53%) normal

                                    Myelocyte: - 0

                                    Metamyelocyte: 0-1%      Juvenile forms (0)

Since there is an elevated content of Stab (band) form of neutrophils, then it is a degenerative left shift.

Explanation

β₂ adrenoreceptors are found on the bronchi; when stimulated by adrenomimetics, they dilate the bronchi thereby relieving the spasm of the smooth muscles of bronchi. The cholinergic receptors (M-, N-) constrict the bronchi which will exacerbate the spasm already present in the bronchi.

Explanation

7.5cmHg – Quiet Inspiration

Explanation

 Leukocytosis is an increase in leukocyte count. Physiological leukocytosis is considered to be a normal response of the organism to certain conditions. Therefore, we can have various forms of physiological leukocytosis, for example:

·        Leukocytosis in newborns

·        Alimentary: usually develops in 2-3hours after meal.

·        Myogenic: may be caused by strenuous physical exertion.

·        Emotiogenic: due to mental stress.

·        Leukocytosis in pregnancy (5-6months of gestation)

The alimentary, myogenic, emotiogenic are usually as a result of redistribution which is transient (with a short-term course) and retain normal proportion of the various forms of leukocytes. The leukocyte commonly involved is the Neutrophil.

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

At puberty, a pool of growing follicles is established and continuously maintained from the supply of primordial follicles. A primary oocyte, together with its surrounding flat epithelial cells forms the primordial follicle. Each month 15 – 20 follicles selected from this pool begin to mature, passing through 3 stages namely: primary or preantral; secondary or antral and preovulatory (graafian follicle). As the primary oocyte begins to grow, surrounding follicular cells change from flat to cuboidal and proliferate to produce a stratified epithelium (which can be 1 - 2 layers but usually more) of granulose cells and the unit is called a primary follicle.

Explanation

The end product of the purine nucleotides catabolism in humans and other primates is uric acid (urate) which is excreted in urine. Allopurinol and febuxostat inhibits Xanthine oxidase (XO). Hypoxanthine and Xanthine which is more soluble is excreted in urine. Purine nucleotides (adenine and guanine).  AMP – Adenosine monophosphate; GMP – Guanosine monophosphate

Pyrimidine (thymine, Uracil, cytosine); catabolism of thymine and uracil gives urea, while catabolism of cytosine gives β-alanine.

Explanation

Foreign bodies (e.g. button) inspired to the trachea are most likely to be found in the right main bronchus because it is wide and believed to be a continuation of the trachea. It runs almost vertically as a continuation of the trachea. It is much shorter but wider than the left.

Explanation

Creatine kinase/Creatine phosphokinase is an enzyme present in striated muscles, used to generate energy. When its serum level is elevated it is often an indication of muscle damage caused by injury, muscular dystrophy or cardiac problems. Most forms of muscular dystrophy are associated with decreased creatinine excretion. Creatinine is a break down product of creatine. Normal constituent of urine but can be elevated in muscular dystrophy. 

Explanation

Explanation

During cerebellar lesions, there  are disturbances in posture, equilibrium and movements. Disturbances in movements: ataxia, asynergia, asthenia (weak muscle contractions with characteristically rapid onset of muscle fatigue), Dysmetria, Intention tremor, astasia (loss of the capacity for sustained tetanic contractions), nystagmus, rebound phenomenon, dysarthria, adiadochokinesis, atonia (lack or impairment of muscle tone).

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 effects makes the patient susceptible to other infectious diseases (e.g. chronic tonsillitis).

Explanation

Explanation

Movement disorders in paralysis may be in a single limb (monoplegia); both upper or lower extremities (upper paraplegia or lower paraplegia); if half of the body (hemiplegia i.e. one hand and one leg on one side of the body); paralysis of all 4 limbs i.e. lower and upper extremities (tetraplegia).

Explanation

Explanation

Agglutinin – antibody; agglutinogen – antigen

     Agglutination: in this test, the antigen is particulate (e.g. bacteria and red blood cells) or is an inert particle (latex beads) coated with an antigen. Because the antibody (agglutinin) is divalent or multivalent, it cross-links the antigenically multivalent particles and forms a latticework; then clumping (agglutination) can be seen. This reaction can be done in a small cup or tube or with a drop on a slide.

Explanation

Inversion involve an end-to-end reversal of a segment within a chromosome e.g. ABCDEF becomes ABFEDC  180⁰.

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

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

The deep palmar arch (arcus Palmaris profundus) is formed by the terminal portion of radial artery and the deep palmar branch of the ulnar artery. The arch resides deep below the tendons of flexors of fingers on the bases of metacarpal bones. The deep palmar arch gives 3 palmar metacarpal arteries; they run along the interosseous muscles to reach the common palmar digital arteries (around the bases of proximal phalanges). Apart from this, they anastomose with the dorsal metacarpal arteries by means of perforating branches. The deep palmar arch can normalize blood flow to the hand in the absence of the superficial palmar arch (superficial blood vessels).

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

Teres major muscle is one of the muscles of the shoulder girdle. It originates from the lower angle and lateral border of the scapula; And inserts into the crest of the lesser tubercle of the humerus. It pulls the shoulder to the back (extension); medially rotates and adducts it.

Explanation

Endometrial hyperplasia usually results with conditions of prolonged estrogen excess and can lead to metorrhagia (uterine bleeding at irregular intervals), menorrhagia (excessive bleeding with menstrual periods) or menometrorrhagia. It is classified into 3 types:

·        Simple hyperplasia (cystic glandular hyperplasia)

·        Adenomatous hyperplasia

·        Atypical hyperplasia

Simple hyperplasia is characterized by the presence of large and cystically dilated, varying-sized glands which are lined by atrophic epithelium. Simple endometrial hyperplasias can cause bleeding but are not thought to be premalignant.

Explanation

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.

Tuberculin (Mantoux) skin test: this test is done by intradermal injection of tuberculoprotein (tuberculin), purified protein derivative (PPD). Type IV hypersensitivity reaction.

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.

Explanation

Adenoma: benign epithelial tumor from the epithelium of the glands and glandular organs. More often they can be found in the breast, thyroid gland, liver, ovaries, prostate gland, GIT. In the question, it is located in the fibrous stroma – FIBROADENOMA.

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. This proteinuria then degenerates into edema because of the decrease in oncotic pressure in the body.

Explanation

       The femur consists of a shaft (body) and two ends, superior/proximal and inferior/distal. The neck of the femur is trapezoidal, with its narrow end supporting the head and its broader base being continuous with the shaft. Fractures of the femoral neck is a very common occurrence in older people as a result of a slight stumble if the neck has been weakened by osteoporosis.

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

     Etiotropic drug deals directly with the etiological factor (diphtheria toxin). Antidiphtheric antitoxic serum neutralizes the toxin of diphtheria and is employed both as a curative and as a prophylactic agent. Diphtheric anatoxin (diphtheria toxoid) is the diphtheria toxin that has been weakened until it is no longer toxic but is strong enough to induce the formation of antibodies and immunity to the disease.

Explanation

One of the most common complications of insulin therapy is hypoglycemia. Normal glucose concentration is 3.3 – 5.5mmol/L. The only option less than 3.3 is 1.5mmol/L which indicates severe hypoglycemia (↓glucose concentration).

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.

Explanation

1.     Rheumatoid (atrophic) arthritis is a chronic progressive inflammatory arthritis of unknown origin involving multiple joints and characterized by disorganization of connective tissue of the synovial membrane and articular cartilage and development of their deformation. Disorganization of the connective tissue cause increase in proteoglycans and glycosaminoglycans (GAGs) concentration in blood. Proteoglycans and GAGs are responsible for the physical properties of ground substance. Main morphological appearance of rheumatoid arthritis is synovitis. It has 3 stages: in the first stage, it is characterized by an acute inflammatory reaction with development of edema, hyperemia and infiltration of lymphocytes, plasma cells and macrophages. Small areas of superficial necrosis or superficial erosions are covered by fibrinoid deposits. Not infrequently 2-3mm “rice bodies” (rice grains) composed of fibrin, fibronectin, collagen and immunoglobulin are present in joint cavities of seropositive patients.

Explanation

Polypous ulcerative endocarditis is a morphological form of septic (bacterial) endocarditis. It develops on both sclerotic and intact valves. Large thromboembolic polyp-shaped plaques appear on sclerotic valves. The plaques are easily crumbled and are saturated with calcium which is characteristic for this pathology. After removal of the plaques, ulcerative defects are seen on the sclerotic and deformed cusps of the valves.

Explanation

Pyruvate kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate during glycolysis (the third irreversible reaction of glycolysis). The normal, mature erythrocyte lacks mitochondria and is therefore, completely dependent on glycolysis for production of ATP. This high energy compound is required to meet the metabolic needs of the red blood cell and to fuel the pumps necessary for the maintenance of the biconcave, flexible shape of the cell which allows it to squeeze through narrow capillaries. The anemia observed in glycolytic enzyme deficiencies is a consequence of the reduced rate of glycolysis leading to decreased ATP production. The premature death and lysis of red blood cells results in hemolytic anemia. Pyruvate kinase deficiency is restricted to the erythrocytes and produces mild to severe chronic hemolytic anemia.

Explanation

Abnormality of constitution, so called diathesis is characterized by pathological reactions on physiological agent. Classification of diathesis:

·        Hemorrhagic: characterized by hemorrhagic reaction to physiological factors.

·        Thymicolymphatic/Lymphohypoplastic: characterized by enlargement of lymphatic nodes, muscular atrophy, individual pale, pastous, predisposing to autoallergic disease, lymphocytosis, angina and other infectious diseases.

·        Neuroarthritic/Gouty: predisposing to arthralgia, arthritis, rheumatism, obesity, gout, psychic disease.

·        Edematic/Exudative: characterized by edema reaction to different environmental factors.

·        Asthenic: expressed in hypodynamia, hypotonia.

Explanation

     Granular or rough endoplasmic reticulum (i.e. rough surface) is a region of endoplasmic reticulum associated with ribosomes. It is the site of protein synthesis and modification of newly synthesized proteins.

Explanation

Giardia lamblia is pear shape or “clownface” with two nuclei, 4 pairs of flagella. The two nuclei are outlined by adhesive discs. Transmitted by cysts in water. The cysts are oval, have 4 nuclei and have clearly visible axostyles. It causes Giardiasis – bloating, flatulence, foul-smelling, fatty diarrhea. Diagnosis: trophozoites or cysts in stool.

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

        Hyperammonemia can be acquired (e.g. liver disease) or hereditary (e.g. urea cycle enzyme deficiencies). Acquired hyperammonemia may be a result of an acute process e.g. viral hepatitis, ischemia or hepatotoxins. As a result, the detoxification of ammonia (i.e. its conversion to urea) is severely impaired, leading to elevated levels of circulating ammonia.

Explanation

Tyrosine is formed from phenylalanine by phenylalanine hydroxylase. Albinism refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of melanin. These defects result in the partial or full absence of pigment from the skin, hair and eyes. In addition to hypopigmentation, affected individuals have vision defects and photophobia (sunlight hurts their eyes). They are at increased risk for skin cancer.

Explanation

The accommodation mechanism, that is, the mechanism that focuses the lens system of the eye – is essential for a high degree of visual acuity. Accommodation results from contraction or relaxation of the eye ciliary muscle. Contraction causes increased refractive power of the lens and relaxation causes decreased power. When viewing far (remote) objects, the ciliary muscle relaxes and the internal media exert a certain pressure on the layer. The ciliary zonule thus appears to be stretched, which in turn results in flattening of the lens because of radial stretching of its capsule. On the contrary, watching the close objects causes the ciliary muscle to contract and it pulls the ciliary body together with the entire vascular layer anteriorly. Circular fibers of the ciliary muscle narrow the opening (pupil) of the ciliary body where the lens is suspended. These two opposing processes are called accommodation. Paralytic state of this muscle will cause a disorder of accommodation.

Explanation

Thymalin is an immunostimulator, it’s the complex of polypeptides fractions of thymus gland of horned cattle. It is a drug of first generation. It stimulate cells immune reactions, restore T lymphocytes quantity and function, correlation of T and B lymphocytes, their subpopulations and increase native killers’ activity, intensify phagocytosis and lymphokines production. It is used in complex therapy of immune deficiency diseases and trophic ulcers.

Explanation

Active forms of oxygen (reactive oxygen species) are formed continuously as by-products of aerobic metabolism, through reactions with drugs and environmental toxins, or when the level of antioxidants is diminished, all creating the condition of oxidative stress. One of the protective mechanisms by which the cell minimize the toxic potential of these compounds is by enzymes that catalyze antioxidant reactions. The 3 most important enzymes are glutathione peroxidase, catalase and superoxide dismutase. The superoxide dismutase is specific for converting superoxide to hydrogen peroxide which is then neutralized by catalase or glutathione peroxidase.

Breakdown of H₂O₂ → H₂O + O₂ to produce foam. In the absence of these enzymes H₂O₂ cannot be broken down.

Explanation

Anterior gray horn of spinal cord contains the nuclei of lower motor neurons (LMN) which are involved in motor function. These nuclei are present in almost all the levels of spinal cord. Alpha motor neurons in the anterior gray horn are large and multipolar cells. Axons of these neurons leave the spinal cord through the anterior root and end in groups of skeletal muscle fibers called extrafusal fibers. Gamma motor neurons are smaller cells scattered among alpha motor neurons. These neurons send axons to intrafusal fibers of the muscle spindle.

Explanation

Satellite cells are interposed between the plasma membrane of the muscle fiber and its external lamina. They are small cells with scant cytoplasm. Satellite cells function as stem cells that, after injury, proliferate to give rise to new myoblasts. As long as the external lamina remains intact, the myoblasts fuse within the external lamina to form myotubes, which then mature into a new fiber.

Explanation

Endotoxins: outer cell membrane of most gram negative bacteria. It is not secreted from the cell. It is the structural part of bacteria (lipopolysaccharide) released when the bacteria is lysed. It was originally theorized that endotoxin is released once the bacteria dies. It is now a known fact that bacteria release small amounts of endotoxin as a part of their normal metabolism although the majority is still retained inside the cell. So when the laevomycetin is used, it kills the bacteria but the deterioration of the patient’s condition is as a result of the endotoxin released when the bacteria died. Effects of endotoxin: fever, hypotension, edema, DIC.

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.

Explanation

Anatomically, the saphenous opening (saphenous hiatus) is an oval opening in the upper mid part of the fascia lata of the thigh. It lies 3 – 4cm below and to the side of the pubic tubercle and is about 3cm long and 1.5cm wide. An inguinal hernia is a protrusion of parietal peritoneum and viscera such as the small intestine through a normal or abnormal opening from the cavity in which they belong. The two types of inguinal hernias are direct and indirect inguinal hernias.

Explanation

Pheochromocytoma is the most common tumor of the adrenal medulla in adults. Most tumors secrete epinephrine, norepinephrine and dopamine which can cause episodic hypertension. There is increases catecholamines and metanephrines in urine and plasma. Epinephrine stimulates glycogen phosphorylase (rate-limiting enzyme in glycogenolysis i.e. breakdown of glycogen to glucose). This results in hyperglycemia (increase glucose conc. in blood). There is also pronounced sympathetic effects throughout the body like dry mouth.

Explanation

Pathogenesis: Acute cardiac insufficiency → ↓cardiac output → ↓blood flow to the kidney → ↓filtration pressure → oliguria.

Explanation

Reticular formation is a diffused mass of neurons and nerve fibers which form an ill-defined meshwork of reticulum in central portion of the brainstem. Functions: Ascending reticular activating system (ARAS) and descending reticular system. The ARAS is concerned with arousal, alertness, attention and wakefulness, emotional reactions, learning processes and conditioned reflexes. Hence, tumor or lesion in ARAS leads to prolonged sleeping or coma.

Explanation

Explanation

* Febris intermittens: characterized by regular alternation of brief attacks of fever (paroxysms) with feverless periods (apyrexia). Attacks occur every 3^rd day, 2^nd day or everyday. Increase temperature persists for several hours, drops to normal and then rises again.

* Febris continua/persistent: elevated temperature persists at a high level, difference between morning and evening temperature does not exceed 1⁰C.

* Febris recurrens: characterized by longer periods of pyrexia than intermittent (5-6days). Question says every 4 days.

* Febris hectic: 3-5⁰C (difference in temperature).

* Febris remittens: difference in temperature exceeds 1⁰C but temperature never falls to normal.

Explanation

Substances absorbed into the bloodstream from the intestine pass through the liver, where toxins are normally removed. Many of these toxins (such as ammonia) are normal breakdown products of the digestion of protein.  Ammonia is produced by amino acid metabolism and intestinal urease-positive bacteria. In physiological conditions, it is mostly present as ammonium (NH₄⁺) in serum. The urea or ornithine cycle, which is fully expressed in the liver exclusively, serves to converts NH₄⁺ to urea prior to renal excretion and to maintain low serum concentrations. 

NH₃ + α-ketoglutarate → Glutamate

α-ketoglutarate is used up which leads to:

·        ↑glutamate → ↑GABA (inhibitory neurotransmitter)

·        Inhibition of citric acid cycle/tricarboxylic acid cycle; this causes impairment of ATP formation.

·        Inhibition of metabolism of amino acids (impairment of transamination reactions).

NH₃ + Glutamate → Glutamine

Glutamine is an amide of glutamic acid which provides a non-toxic storage and transport form of ammonia (NH₃). Ammonia increase synthesis of glutamine in brain. Accumulation of glutamine in brain results in elevation of osmotic pressure in nervous cells leading to brain edema.

                                    NH₃ + H⁺ → NH₄⁺

In blood ammonia (NH₃) is represented as ammonium ion (NH₄⁺). Accumulation of ammonium ion impairs transport of ions (Na⁺, K⁺) through cell membranes and failure of transmission of nerve impulse. 

Explanation

Ascaris lumbricoides (giant roundworm) is the causative agent of Ascariasis. Transmission: fecal-oral; eggs are visible in faeces under microscope. Some patients may have pulmonary symptoms or neurological disorders during migration of the larvae. A bolus of worms may obstruct the intestine; migrating larvae may cause pneumonitis 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

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

       Sleep is the natural periodic state of rest for mind and body with closed eyes characterized by partial or complete loss of consciousness. Sleep is unconsciousness from which the person can be aroused by sensory or other stimuli. It is to be distinguished from coma, which is unconsciousness from which the person cannot be aroused. During sleep, most of the body functions are reduced to basal level or even below the basal level. Therefore, power inputs can be lower than basal level during sleep. Unlike rest where it remains at the basal level or higher.

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

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is an inherited disease characterized by hemolytic anemia caused by the inability to detoxify oxidizing agents. Diminished G6PD activity impairs the ability of the cell to form the NADPH that is essential for the maintenance of the reduced glutathione pool. This results in a decrease in the cellular detoxification of free radicals and peroxides formed within the cell. Although G6PD deficiency occurs in all cells of the affected individual, it is most severe in erythrocytes where the pentose phosphate pathway provides the only means of generationg NADPH. Some patients with G6PD deficiency develop hemolytic anemia if they are treated with an oxidant drug (e.g. antimalarial – primaquine, chloroquine); ingest fava beans or contract a severe infection.

Explanation

Catarrhal inflammation is one of the morphologic patterns in acute inflammation. In this type, a surface inflammation is associated with greatly increased secretion of clear mucus (nasal discharges). Rhinitis is inflammation of mucous lining of the nose.

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.

Explanation

Explanation

The space between the peritoneal plates of the broad ligament mostly in its inferior portion is filled with fat called the parametrium. Inflammation of the fat – parametritis, is common in clinical practice.

Explanation

Barr body is an inactive X-chromosome. A normal female has one barr body XX; so in turner’s syndrome, there is no barr body because the only X present is the active one (45 XO); likewise in a normal male fetus XY

Explanation

A true vitamin K deficiency is unusual because adequate amounts are generally produced by intestinal bacteria or obtained from the diet. If the bacterial population in the gut is decreased e.g. by antibiotics (leading to dysbacteriosis), the amount of endogenously formed vitamin is depressed and this can lead to hypoprothrombinemia (↓prothrombin) which results in hemorrhagic syndrome.

Explanation

Dysentery refers to bloody diarrhea with mucus. It refers to diarrhea with abdominal cramping and tenesmus in which loose stools contain blood, pus and mucus. Bacillary dysentery is caused by shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonnei. Morphology: it has 4 stages namely: catarrhal colitis; fibrinous colitis; ulcer formation (ulcerative colitis); healing of the wound. Complications of dysentery includes perforation, intraintestinal hemorrhage and eventually death may result from intestinal or extraintestinal complications.

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

Ketamin is an intravenous anesthesia. It is an antagonist of glutamic acid, blocking the actions of this excitatory transmitter. The drug is a cardiovascular stimulant and this action may lead to an increase in intracranial pressure. Reactions such as disorientation, excitation and hallucinations can occur during recovery from ketamin anesthesia. It has no effect on laryngeal reflexes. Skeletal muscle tone, heart rate, arterial blood pressure and cerebrospinal fluid pressure can be increased by ketamin.

Explanation

Disulfiram inhibits acetaldehyde dehydrogenase (acetaldehyde accumulates, contributing to hangover symptoms).

Fomepizole inhibits alcohol dehydrogenase and is an antidote for methanol or ethylene glycol poisoning.

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

Explanation

Parathyroid hormone: secreted by chief cells of parathyroid gland. Effects include:

↑bone resorption of Ca²⁺ and PO₄^3- → ↑their plasma levels

↑kidney reabsorption of Ca²⁺ in distal convoluted tubule → ↑ Ca²⁺ plasma level

↓reabsorption of PO₄^3- in proximal convoluted tubule → ↓ PO₄^3- plasma levels

↑Calcitriol (vit D₃) production by stimulating kidney 1α-hydroxylase in proximal convoluted tubule. It increases Ca²⁺ and PO₄^3- absorption in the intestine.

In general, parathyroid hormone ↑ Ca²⁺ plasma level but ↓ PO₄^3- plasma levels. Abnormal synthesis (↑synthesis) of parathyroid hormone can lead to hypercalcemia and hypophosphatemia.

Explanation

The sinoatrial (SA) node is a small strip of modified cardiac muscle, situated in the superior part of lateral wall of right atrium, just below the opening of superior vena cava. The fibers of this node do not have contractile elements. SA node is called the pacemaker because the rate of production of impulse (rhythmicity) is higher in SA node than in other parts. The rate is 60-100/min and higher during tachycardia when stimulated by sympathetic effects. Atrioventricular (AV) node is 40-60/min.

Explanation

          Pressure in each heart chambers:

Only the left ventricle can range from 0-120mmHg

Explanation

Surfactant is particularly important for survival of the premature infant. When surfactant is insufficient, the air-water (blood) surface membrane tension becomes high, bringing great risk that alveoli will collapse during expiration. As a result, respiratory distress syndrome (RDS) develops. This is a common cause of death in the premature infant. Recent development of artificial surfactant and treatment of premature babies with glucocorticoids to stimulate surfactant production have reduced the mortality associated with RDS and allowed survival of some babies as young as 5.5months of gestation.

Explanation

Macroscopically, sarcoma looks like “fish flesh”. Fibrosarcoma occurs in deep soft tissue sites, showing increased fibroblastic cells, anaplasia and abundant mitotic figures. It looks like node or encapsulated formation.

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.

Explanation

Explanation

* Type I: Allergic and atopic disorders (e.g. rhinitis, hay fever, asthma); Anaphylaxis. Presentation – immediate, anaphylactic, atopic

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

Pulmonary embolism is the most common and fatal form of venous thromboembolism in which there is occlusion of pulmonary arterial tree by thromboemboli. Pulmonary emboli are more common in hospitalized or bedridden patients. The majority of emboli arise from the deep veins of the lower extremities; most of the fatal ones arise from the ileofemoral veins. Consequences of thromboembolism include pulmonary infarction in which pyramidal segments (or ‘triangular’ segments) of hemorrhagic infarction are seen at the periphery of the lung. Detachment of thrombi from the thrombophlebitis site in the lower limbs produces a thromboembolus that flows through venous drainage into the large veins draining into the right side of the heart and then to the pulmonary circulation where they embolize.

Explanation

Explanation

Explanation

Explanation

Paget’s disease of nipple: the nipple bears a crusted, scaly eczematoid lesion with a palpable subareolar mass in about half the cases. Microscopically, the skin lesion is characterized by the presence of Paget’s cells singly or in small clusters in the epidermis. These cells are larger than the epidermal cells, spherical having hyperchromatic nuclei with cytoplasmic halo that stains positively with mucicarmine. Paget’s cells show an empty cytoplasm.