practice

Explanation

        X-linked dominant: it can be transmitted through both parents. Mothers transmit to 50% of daughters and sons; fathers transmit to all daughters but no son (father-daughters; no generation is left out).

X-linked recessive: sons of heterozygous mothers have a 50% chance of being affected. No male-to-male transmission. Recessive genetic diseases skips generations.

Y-linked: father to all sons; no female involvement (mother or daughter)

Autosomal dominant and recessive

Explanation

1.     Glycogen phosphorylase is the rate-determining enzyme in Glycogenolysis (break down of glycogen). Glycogen phosphorylase cleaves glycogen to glucose 1-phosphate (first step in glycogenolysis). This pathway mobilizes stored glycogen in liver to replenish used glucose. It also breaks down glycogen in muscle to glucose, to produce energy during physical work. If this enzyme is deficient, then used glucose cannot be replaced leading to hypoglycemia.

In lysosomal glycosidase, there is still normal blood sugar levels (no hypoglycemia). α-amylase and ɣ-amylase is involved in digestion of polysaccharides. Glucose 6-phosphate dehydrogenase (G6PD) is the rate-limiting enzyme in pentose phosphate pathway which catalyzes an irreversible oxidation of glucose 6-phosphate to 6-phosphogluconolactone.

Explanation

Explanation

      Recessive because a generation was left out (skipped- grandfather to son); it is sex linked because its from grandfather to son (only the male is involved).

Explanation

1.     Aa X Aa

AA  Aa  Aa  aa

AA-healthy (25%)

Aa-carriers (heterozygous; 50%)

aa-sick with hemophilia (25%)

Option B will not produce a sick child.

Option C: all children will be sick.

Option D: 50% of children are carriers; the other 50% have hemophilia

Option E: 75% are healthy; 25% has hemophilia

Explanation

Mental artery is the terminal branch of inferior alveolar artery. It supplies the mental region (chin) and the lower lip.

Inferior labial is a branch of facial artery that supplies the lower lip. Lingual artery supplies the tongue. Facial artery gives branches such as ascending palatine artery, submental artery, superior and inferior labial arteries and angular artery. Palatine artery supplies the palate.

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. Since creatine is not a normal constituent of urine, it is more specific in this case.

Explanation

Lingual nerve is a branch of mandibular nerve (CNV₃). Mandibular nerve is the third division of the trigeminal nerve. It’s a sensory nerve that transmits the impulses of pain, temperature and tactile sensitivity. Glossopharyngeal provides taste and tactile sensory innervations to the posterior 1/3 of the tongue.

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. 

There is an impaired perception of high frequency sounds; that means there is damage near the base of cochlea (i.e. near the round and oval windows).

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.

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.

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

Explanation

      Deltoid muscle (M. deltoideus): abducts the shoulder; anterior fibers flex the shoulder, while posterior fibers extend it.

Triceps brachii and anconeus extends the forearm; the long head of triceps brachii extends and adducts the shoulder; coracobrachialis muscle flexes and adducts the arm; supinators rotates (supinates) the forearm.

Explanation

The closest bile excreting duct to the pancreas is the common bile duct (ductus choledochus). So, in case of a tumor affecting the pancreas, this can compress the bile duct, thereby obstructing bile flow leading to mechanic, obstructive or post-hepatic jaundice.

Explanation

     In the female lesser pelvis, there are two excavations: the rectouterine pouch and vesicouterine pouch. The rectouterine pouch (pouch of douglas) is an intraperitoneal space between the uterus and the rectum. It is a common place for pelvic fluid or blood from hemorrhage to collect after surgery, or rupture of any etiology.

The vesicouterine pouch is between the urinary bladder anteriorly and the uterus posteriorly. It is a shallower recess (pouch).

Explanation

     Entamoeba histolytica is a protozoa causing gastrointestinal infections, which can lead to amebic dysentery or liver abscess. It is transmitted by its cysts in water. It is diagnosed by stool samples or serological methods: trophozoites (with RBCs in the cytoplasm) or cysts (with up to 4 nuclei) in stool.

Explanation

1.     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

Metaplasia is a reversible change of one type to another type of adult epithelial or mesenchymal cells, usually in response to abnormal stimuli and often reverts back to normal on removal of stimulus. Types (2):

·        Epithelial: Squamous metaplasia: in bronchus (chronic smokers), cervix

  Columnar metaplasia: there is transformation to columnar epithelium.

·        Mesenchymal metaplasia: osseous and cartilaginous.

Hyperplasia: ↑number of cells; Hypertrophy: ↑in size.

Explanation

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

The orthochromatophilic erythroblast (normoblast) has a small, compact, densely stained nucleus. The cytoplasm is eosinophilic because of the large amount of hemoglobin. It is only slightly larger than a mature erythrocyte. It loses its nucleus  by extruding it from the cell, it is then ready to pass into a blood sinus of the red bone marrow.

Explanation

Reflex activity is the response to a peripheral nervous stimulation that occurs without our consciousness. It can be:

* Inborn or unconditioned: present from birth, does not require previous learning or training.

* Acquired or conditioned: developed after conditioning or training. Acquired after birth.

It is conditioned because the students have had a previous experience with examinations before. The manifestation of dry mouth is a sympathetic effect.

Explanation

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

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

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

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

Explanation

1.     Cardiac muscle has the same types and arrangement of contractile filaments as skeletal muscle. Cardiac muscle fibers exhibit densely staining cross bands called intercalated disks, that cross the fibers in a linear fashion or frequently in a way that resembles the risers of a stairway. The intercalated disks represent highly specialized attachment sites between adjacent cells. The cardiac muscle nucleus lies in the center of the cell which is one feature that helps distinguish them from multinucleated skeletal muscle fibers, whose nuclei lie immediately under the plasma membrane. Cardiac muscle cells exhibit a spontaneous rhythmic contraction.

Explanation

·        Cholecystokinin-pancreozymin: source – I cells in duodenum and jejunum of small intestine. Action – increase pancreatic secretion, gallbladder contraction, sphincter of oddi relaxation and decrease gastric emptying. It acts on neural muscarinic pathways to cause pancreatic secretion.

·        Somastostatin: source – D cells (pancreatic islets, gastrointestinal mucosa). Action – decrease gastric acid and pepsinogen secretion; decrease pancreatic and small intestine fluid secretion; decrease gallbladder contraction; decrease insulin and glucagon release.

·        Secretin: source – S cells (duodenum). Action – increase pancreatic HCO₃^- secretion ( ↑ bicarbonate secretion); increase bile secretion; decrease gastric acid secretion.

·        GIP: source - K cells in duodenum and jejunum. Action – exocrine action: decrease gastric hydrogen ion (H⁺) secretion; endocrine action: increase insulin release. It is also known as Glucose-dependent insulinotropic peptide.

·        VIP: parasympathetic ganglia in sphincters, gallbladder, small intestine. Action – increase intestinal water and electrolyte secretion, relaxation of intestinal smooth muscle and sphincters.

Only cholecystokinin-pancreozymin increase pancreatic secretion. Secretin only increases pancreatic HCO₃^- secretion which neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function.

Explanation

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

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

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

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

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

Explanation

All muscles that elevate the rib cage are muscles of inspiration and those that depress the rib cage are muscles of expiration.

Muscles of inspiration:

·        Sternocleidomastoid: lift upward on the sternum.

·        Anterior serrati: lift many of the ribs.

·        Scalene: lift the first two ribs.

Muscles of expiration: Abdominal recti – pull down the lower ribs and other abdominal muscles also compress the abdominal contents upwards against the diaphragm and internal intercostals.

Normal respiration is accomplished by the movement of the diaphragm only.

Explanation

↓blood supply → activates renin. Renin catalyzes the conversion of angiotensinogen to angiotensin I. Angiotensin converting enzyme (ACE) converts angiotensin I → angiotensin II. Angiotensin II causes:

- vasoconstriction → ↑BP

- vasopressin (ADH) → ↑H₂O reabsorption → ↑plasma volume

- aldosterone → ↑Na⁺ and H₂O reabsorption → ↑plasma volume → ↑BP

Explanation

Explanation

↑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.

Calcitonin is secreted by parafollicular cells (C cells of the thyroid gland). It ↓bone resorption of Ca²⁺. It opposes actions of parathyroid hormone. But its not important in normal Ca²⁺ homeostasis. Calcitriol ↑ circulating Ca²⁺ ions as a means of enhancing intestinal absorption of calcium (NB: Calcitriol production is dependent on parathyroid hormone). Aldosterone: reabsorption of Na⁺, excretion of K⁺. Cortisol – glucocorticoid: ↑ blood pressure and gluconeogenesis; ↓ inflammatory and immune responses; ↓ bone formation (↓osteoblast activity).

Likewise, deficiency of parathormone can lead to low Ca²⁺ levels.

Explanation

   One of the properties of synapse is fatigue. During continuous muscular activity, synapse becomes the seat of fatigue along with Betz cells present in motor area of frontal lobe of cerebral cortex. Fatigue at synapse is due to the depletion of neurotransmitter substance, acetylcholine. Depletion of acetylcholine occurs because of 2 factors:

·        Soon after the action, acetylcholine is destroyed by acetylcholinesterase.

·        Due to continuous action, new acetylcholine is not synthesized.

The excitatory terminals on many neurons can store enough excitatory transmitter substance to cause only about 10,000 action potentials and the neurotransmitter can be exhausted in only a few seconds to a few minutes of rapid stimulation.

            It is fatigue of central synapses because only the function of muscle   coordination is affected which is an exclusive function of the higher brain centers. Force of contraction s determined by discharge at neuromuscular synapses in the neuromuscular junction.

Explanation

Reflex arch is the anatomical nervous pathway for a reflex action. A simple reflex arc has 5 components:

·        Receptor: end organ, which receives the stimulus.

·        Afferent nerve or sensory nerve: transmits sensory impulses from the receptor to center.

·        Center: receives the sensory impulses via afferent nerve fibers and in turn, it generates appropriate motor impulses. Center is located in the brain or spinal cord.

·        Efferent nerve or motor nerve: transmits motor impulses from the center to the effector organ.

·        Effector organ: is the structure such as muscle or gland where the activity occurs in response to stimulus.

When a reflex activity is continuously elicited for a long time (long training session), the response is reduced slowly and at one stage, the response does not occur. This stage of failure to give response to the stimulus is called fatigue. Center or the synapse of the reflex arc is the first seat of fatigue.

Explanation

Blood minute volume is the amount of blood pumped out by each ventricle in one minute. It is the product of stroke volume and heart rate. Normal value is 5L/ventricle/minute.

If blood minute volume is 5L/m; the volume pumped through the pulmonary vessels (lung vessels) per minute by the right ventricle equals 5L.

Explanation

1.     Thrombocyte (platelet) is involved in primary hemostasis. It’s a small cytoplasmic fragment derived from megakaryocytes. It has a life span of 8-10days. When activated by endothelial injury, it aggregates with other platelets and interacts with fibrinogen to form platelet plug. Thrombocytopenia or decrease platelet function/dysfunction results in petechiae.

Leukocytes: Neutrophils (54-62%); Lymphocytes (25-33%); Monocytes (3-7%); Eosinophils (1-3%); Basophils (0-0.75%). Neutrophils, eosinophils, basophils are granulocytes; while lymphocytes, monocytes are mononuclear cells and they are also agranulocytes. They are all responsible for defense against infections.

Explanation

Blood minute volume is the amount of blood pumped out by each ventricle in one minute. It is the product of stroke volume and heart rate. Normal value is 5L/ventricle/minute.

If blood minute volume is 5L/m; the volume pumped through the pulmonary vessels (lung vessels) per minute by the right ventricle equals 5L.

Same for any value given.

Explanation

Explanation

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

Atrial natriuretic peptide is secreted in response to increase atrial pressure. It causes increase glomerular filtration rate (GFR) and increase sodium ion filtration with no compensatory sodium ion reabsorption and water in distal nephron which leads to increase diuresis.

Parathyroid hormone is secreted in response to decrease plasma calcium ion, increase phosphate ion or decrease plasma calcitriol [1,25-(OH)₂D₃].

Explanation

1.     The superior vena cava (SVC) arises from merging left and right brachiocephalic veins posterior to the right first sternocostal joint. The SVC descends to enter the right atrium. On the left, one can distinguish the ascending aorta and on the right – the mediastinal pleura and phrenic nerve. The right pulmonary vein resides posterior to the SVC & the thymus and the right lung – anterior to it. Therefore, thymoma (thymus gland tumor) will definitely press on the SVC. The brachiocephalic veins drain the head, neck and upper limbs; hence, the manifestations.

Explanation

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

 Hypothalamus is a diencephalic structure. Diencephalon: thalamus, hypothalamus, pineal body, third (3^rd) ventricle. The Hypothalamus is situated just below thalamus in the ventral part of diencephalon. It is the important part of brain, concerned with homeostasis of the body. It regulates endocrine functions, metabolic activities, hunger, thirst, sleep, wakefulness, emotion, sexual functions. Lesion of hypothalamus can occur due to tumors, encephalitis and ischemia; accompanied by disturbances in carbohydrate and fat metabolisms; disturbance in sleep and sexual functions. It can also result in some clinical manifestations such as: Diabetes insipidus, dystrophia adiposogenitalis, kallmann syndrome, Laurence-Moon-Biedl syndrome, narcolepsy, cataplexy.

Explanation

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

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

Explanation

Vitamin P (rutin) – permeability vitamin. They reduce permeability of blood vessels, especially capillaries. It prevents hyaluronic acid (the basic compound of the extracellular matrix) from degeneration by inhibition of the enzyme hyaluronidase. Ascorutin is a drug containing vitamin C and P; it is used to decrease the permeability of blood vessels.

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

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

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

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

Vitamin A (retinol) deficiency – Night blindness

Vitamin B₉ (folic acid) deficiency – macrocytic megaloblastic anemia

Explanation

   Phenylketones – phenylacetate, phenyllactate and phenylpyruvate. These compounds are not normally produced in significant amounts in the presence of functional phenylalanine hydroxylase, but are elevated in phenylketonuria. These metabolites give urine a characteristic musty (“mousey”) odour. The disease acquired its name from the presence of a phenylketone (now known to be phenylpyruvate) in the urine.

Phenylketonuria (PKU) is caused by a deficiency of phenylalanine hydroxylase. PKU is the most common clinically encountered inborn error of amino-acid metabolism. Biochemically, it is characterized by accumulation of phenylalanine and a deficiency of tyrosine. It may also be caused by deficiencies in tetrahydrobiopterin cofactor (BH₄) or in dihydropteridine (BH₂) reductase, which regenerates BH₄ from BH₂.

Explanation

Duplications occur when a portion of the chromosome is present on the chromosome in two copies.

Inversion involve an end-to-end reversal of a segment within the same chromosome (turn of 180^o).

Deletion is a mutation in which a part of a chromosome or a sequence of DNA is missing. Deletion is the loss of genetic material.

Explanation

Myeloma/Plasmocytoma/Multiple Myeloma

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

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

Explanation

In the liver and muscle, insulin increases glycogen synthesis. In the muscle and adipose tissue, insulin increases glucose uptake by increasing the number of glucose transporters (GLUT-2) in the cell membrane. Insulin is an anabolic hormone; it increases glucose uptake, glycogen synthesis, protein synthesis, fat synthesis; and decrease gluconeogenesis, glycogenolysis, lipolysis. Gluconeogenesis is the production of glucose from non-carbohydrate sources.

Glucagon is a functional antagonist of insulin.

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

       Kidneys excrete the unwanted waste products which are formed during metabolic activities e.g.

·        Urea: end product of amino acid metabolism

·        Uric acid: end product of nucleic acid metabolism

·        Creatinine: end product of metabolism in muscles

·        Bilirubin: end product of hemoglobin degradation

·        Products of metabolism of other substances.

Many substances both organic and inorganic are excreted in saliva also. In some pathological conditions, saliva excretes certain substances which are not found in saliva under normal conditions e.g. glucose in Diabetes mellitus. In certain conditions, some of the normal constituents of saliva are excreted in large quantities e.g. excess urea is excreted in saliva during renal failure, nephritis and excess calcium is excreted during hyperparathyroidism.

Explanation

 Indirect anticoagulants:

·        Coumarine derivatives – Neodicumarin, warfarin, syncumar

·        Indandione derivatives – Phenylinum

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

Factor II – Prothrombin

Factor VII – Stable factor

Factor IX – Christmas factor

Factor X – Stuart-Prower factor

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

All other options are not clotting factors.

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

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.

The nuclear radiation this patient was exposed to can produce inflammatory reaction in the patient. Within the first 24hours, the first leukocyte to get into any inflammatory focus are the neutrophils, followed by the monocytes (macrophages) and then lymphocytes.

Explanation

1.     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

Chronic renal failure is the progressive, long standing and irreversible impairment of renal functions. When some of the nephrons loose their function, the unaffected nephrons can compensate for it. However, when more and more nephrons start losing their function over the months and years, then the compensatory mechanism fails and chronic renal failure manifests.

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)

This is an example of type I hypersensitivity reaction with the expression of eosinophilia.

Explanation

No1 is the Obturator artery...

   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.

Femoral artery arises directly from the external iliac artery. On leaving the vascular space, it appears within the femoral triangle together with the femoral nerve (laterally) and femoral vein (medially).

The external iliac artery descends on the medial aspect of psoas major muscle and quits the lesser pelvis via the vascular space to become continuous with the femoral artery. Common iliac arteries gives both external and internal iliac arteries.

Inferior gluteal artery leaves the lesser pelvis cavity via the infrapiriform foramen. Within the gluteal region, it supplies the gluteus maximus and other related muscles.

Internal pudendal artery passes inferolaterally, anterior to the piriformis muscle and sacral plexus. It leaves the pelvis between the piriformis and the coccygeus muscles by passing through the inferior part of the greater sciatic foramen.

Explanation

Explanation

* Protopathic pain: poorly localized pain

* Radiating pain: perceived at a site adjacent to or away from the site of origin but in the same dermatome i.e. supplied by afferent nerve fibers of one dorsal root.

* Viscera pain: organs, poorly localized, diffuse

* Epicritic pain: well localized pain

* Phantom pain: pain from non-existent body structures (amputated limbs)

Phantom – if a leg has been amputated, the cut end heals with scar formation. The cut ends of nerve fibers are merged within the scar. If the cut end of sensory fibers are stimulated during movement of thigh, the patient feels as if the sensation is originating from non-existent leg. Sometimes the patient feels pain in non-existent limb.

Explanation

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

After a physical stress – sudden and rapid – ACUTE

Rales are caused by congestion of the lungs – left ventricular heart failure.

Explanation

      Macrolides inhibit protein synthesis by blocking translocation, they bind to the 23S rRNA of the 50S ribosomal subunit. It is bacteriostatic. Examples of macrolides includes azithromycin, clarithromycin, erythromycin etc.

All other options are not macrolides, but are antibiotics.

Ampicillin is an extended spectrum penicillin; a β-lactam antibiotic.

Gentamycin and streptomycin are Aminoglycosides. Together with tetracyclines, they are 30S ribosomal subunit inhibitor.

Explanation

Chronic myeloleukemia is characterized by extensive production of blast (immature) cells in the blood. The immature cells (e.g. immature RBCs) cannot perform the normal function of a mature cell, hence the manifestation of anemia. The many blast cells constitute the majority of cells found in blood during leukemia. Therefore, as soon as cells die they are replaced by the immature ones, which are usually overproduced in leukemia.

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

      Stroke is sudden loss of blood circulation to an area of the brain resulting in a corresponding loss of neurologic function. Types:

·        Ischemic (70-80% of cases):

- Atherosclerotic (thrombotic): most common type

- Embolic

·        Intracerebral hemorrhage

·        Subarachnoid hemorrhage

·        Lacunar stroke

Atherosclerotic (thrombotic) stroke: Ischemic type of stroke is commonly caused by platelet thrombosis that develops over a disrupted atherosclerotic plaque. Characteristics: it usually develops at the periphery of the cerebral cortex, swelling of brain, loss of dermacation between gray and white matter, breakdown of myelin, pale infarct; Cystic area develops after 10days to 3weeks due to liquefactive necrosis.

Explanation

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

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

·        Non-forming CO₂: magnesium hydroxide, aluminum hydroxide

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

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

Explanation

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

Explanation

Secondary tuberculosis usually results from reactivation of dormant, endogenous tubercle bacilli in a sensitized patient who has had previous contact with the tubercle bacillus. Reactivation typically begins in the apical or posterior segments (often 1^st and 2^nd segments) of one or both upper lobes (“simon’s foci”), where the organisms were seeded during the primary infection. There are 8 forms or stages of the secondary tuberculosis: Acute local tuberculosis; Fibrous local tuberculosis; Infiltrative tuberculosis; Tuberculoma; Caseous pneumonia; Acute cavernous tuberculosis; Fibrous cavernous tuberculosis; Cirrhotic tuberculosis.

Fibrous cavernous tuberculosis is the most frequent form. Macroscopically, the lesions are spherical and cavitary (cavity can contain blood and blood clots); the so-called coin lesions. Microscopically, the outer wall of cavity shows fibrosis or sclerosis. Internal surface may be connected with bronchus. The wall of cavern has 3 membranes:

·        Internal membrane occurs by necrotic tissue

·        Middle membrane occurs by special granular tissue

·        External membrane occurs by connective fibrous tissue

Explanation

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

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

Explanation

   Acute tubular necrosis/Necrotic nephrosis/Necronephrosis involves the death of tubular epithelial cells that form the renal tubules of the kidneys. Most common cause of acute renal failure. It can be ischemic or nephrotoxic.

·        Ischemic acute tubular necrosis occurs due to hypoperfusion of the kidneys.

·        Nephrotoxic acute tubular necrosis occurs as a result of direct damage to tubular cells by ingestion, injection or inhalation of a number of toxic agents. Toxic agents causing nephrotoxic acute tubular necrosis includes mercuric chloride, ethylene glycol, carbon tetrachloride etc.

Macroscopically, the kidneys are enlarged and swollen (edematous). On cut section, the cortex is pale, while the medulla is slightly darker than normal. The capsule can be easily removed.

Explanation

Explanation

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

Type II (cytotoxic): antibody dependent reactions e.g. Goodpasture syndrome, Myasthenia gravis, Graves disease, ABO hemolytic disease of newborn etc.

Type III (immune-complex): deposition of antigen-antibody complexes e.g. systemic lupus erythromatous (SLE), Arthus reaction, serum sickness, poststreptococcal glomerulonephritis etc.

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

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. 

Explanation

  Neisseria diplococcic are gram negative cocci that resemble paired kidney beans/coffee grains. The genus Neisseria contains two important human pathogens: Neisseria meningitides and Neisseria gonorrhoeae. Portal of entry is respiratory and genital tracts respectively. Meningococcal infection is an acute infectious process which has 3 main forms: nasopharyngitis; purulent meningitis and meningococcemia.

Meningitis is an acute or chronic inflammatory process chiefly affecting the pia and arachnoid mater (brain tunics) and cerebrospinal fluid. Meningococcal meningitis is characterized by the hyperemia of the pia mater, saturated with dull serous exudates during the first days of the disease.

Explanation

        Hyperplasia of endometrium is classified into 3 types:

·        Simple hyperplasia (cystic glandular hyperplasia)

·        Adenomatous hyperplasia (complex hyperplasia without atypia)

·        Atypical hyperplasia (complex hyperplasia with atypia)

Simple hyperplasia (cystic glandular hyperplasia) is characterized by the presence of large and cystically dilated varying-sized glands, which are lined by atrophic epithelium.

Explanation

     There are two medically important genera of gram positive cocci: staphylococcus and streptococcus. Microscopically, staphylococci appear in grape-like clusters, whereas streptococci are in chains or pairs. Streptococcus pneumonia causes pneumonia, bacteremia, meningitis and infections of the upper respiratory tract. Pneumococci are gram positive lancet-shaped cocci arranged in pairs (diplococci) or short chains. The term “lancet-shaped” means that the diplococci are oval with somewhat pointed ends rather than being round).

Klebsiella and the Neisseria genus are gram negative.

Explanation

    Agglutination is commonly used as a method of identifying specific bacterial antigens and in turn the identity of such bacteria. Because the clumping reaction occurs quickly and is easy to produce, agglutination is an important technique in diagnosis. It is the clumping of cells such as bacteria or red blood cells in the presence of an antibody or complement. The antibody or other molecule binds multiple particles and joins them creating a large complex. The antibody (agglutinin) and antigen (agglutinogen) take part in the agglutination reaction. Their interaction takes place in definite quantitative proportions and in the presence of an electrolyte (0.85% NaCl solution). In mechanism and outer manifestation, the agglutination reaction is similar to the precipitin reaction. Both reactions are accompanied by the production of visible precipitates of antigen with the difference that in the agglutination reaction microbial bodies serve as the antigen, whereas in the precipitin reaction (precipitation reaction) the antigen is the product of the breakdown of microbial bodies, very minute particles of dissolved antigens requiring a large amount of antibodies for complete interaction.

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

      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

     Digitoxin is a long acting cardiac glycoside; used to treat chronic heart failure I-IIB stages, supraventricular tachyarrhythmia (fibrillation, Wolff-Parkinson-White syndrome). Since the patient has been taking this drug in  self-administered doses, there is a high probability of taking an overdosage which can result in toxic concentrations and at toxic concentrations, it causes ectopic ventricular beats that may result in ventricular tachycardia and fibrillation (arrhythmia). This arrhythmia is usually treated with lidocaine or phenytoin but in the absence of this, the first action to take is to stop taking the drug completely (to withhold digitoxin).

Explanation

      Diabetes insipidus (D.I.) is characterized by intense thirst and polyuria (hyperdiuresis) with inability to concentrate urine due to lack of ADH (central D.I.) or failure of response to circulating ADH (nephrogenic D.I.). in central D.I. antidiuretic hormone (ADH) is decreased; in nephrogenic D.I. ADH is normal. Therefore, the hormonal drug we can use to treat diabetes insipidus is to replace the low antidiuretic hormone (ADH) in central diabetes insipidus. So, we use ADH – a posterior pituitary hormone which increases water reabsorption in renal tubules and decrease dieresis. Its analogue desmopressin acetate can also be administered intranasally. Nephrogenic diabetes insipidus does not require hormonal replacement.

Explanation

Explanation

   Hypoglycemic coma is an acute condition progressing during rapid reduction of glucose level in blood and abrupt lowering of glucose utilization by brain. Overdosage of insulin is the most common cause; other causes are alcohol, overdose of oral hypoglycemic agents, insulinoma etc.

Treatment: for correction of hypoglycemia

20.0-60.0ml of 40% solution glucose intravenously (IV)

500ml of 5% solution glucose IV drip feed; or

Subcutaneous injection of glucagon 1.0ml

Subcutaneous injection of 1.0ml – 0.1% adrenaline (epinephrine)

Explanation

      Methyluracil is a nonsteroidal anabolic, it can also act as a leucopoiesis stimulator, a non-specific drug which stimulates nucleic acid synthesis and proteins sufficient for leucopoiesis and other regeneration processes. Uses – radiation skin damages, fractures, slow recovering burns, agranulocytosis and leucopenia.

Cyclophosphan and Methotrexate are anticancer drugs

Prednisolone (glucocorticoids) and cyclosporine are immunosuppressants.

Explanation

    Oxidation of the heme component of hemoglobin to the ferric (Fe³⁺) state forms methemoglobin, which cannot bind O₂. This oxidation may be caused by the action of certain drugs or substances containing nitrates, or endogenous products such as reactive oxygen intermediates. Furthermore a deficiency of NADH-met-hemoglobin reductase i.e. the enzyme responsible for the conversion of methemoglobin (Fe³⁺) to hemoglobin (Fe²⁺); leads to the accumulation of methemoglobin. The methemoglobinemias are characterized by “chocolate cyanosis” (a brownish-blue colouration of the skin and  membranes) and chocolate-coloured blood, as a result of the dark-coloured methemoglobin. Symptoms are related to tissue hypoxia and include anxiety, headache and dyspnea. Treatment is with methylene blue, which is oxidized as Fe³⁺  is reduced.

Explanation

Explanation

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

Parents are healthy. Grandfather –Boy. A generation was left out (skipped).

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).

Explanation

    The pox virus family includes 3 viruses of medical importance: smallpox virus, vaccinia virus and molluscum contagiosum virus (MCV). Poxviruses are the largest and most complex viruses. The smallpox virus is also called variola virus. It is the agent of smallpox, the only disease that has been eradicated from the face of the earth. Eradication is due to the vaccine. Smallpox virus is transmitted via respiratory aerosol or by direct contact with virus either in the skin lesions or on fomites such as bedding. The virus replicates in the cytoplasm which form inclusion bodies (paschen) stainable in the cytoplasm of infected cells.

Negri bodies are inclusion bodies in Rabies; Guanieri bodies are inclusion bodies in vaccinia, variola (Note: vaccinia virus is nonpathogenic for humans); but paschen bodies is specific and pathognomonic for variola or smallpox.

Explanation

Explanation

     The presence of the antitoxic diphtheria serum (antibody) and the exotoxin (antigen) cause an interaction between them leading to the production of antigen-antibody complexes producing precipitates (precipitin lines) on the strip of filter paper. We will have a precipitin ring if a tube were to be used instead of a filter paper.

Explanation

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

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

She has been suffering it for 15 years – chronic

Edema of lower limbs, ascites – Right ventricular insufficiency

Explanation

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

·        Macula of Utricle

·        Macula of Saccule

·        Ampullary crests

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

Explanation

        Helicobacter pylori causes gastritis and peptic ulcers. Infection with H. pylori is a risk factor for gastric carcinoma and is linked to mucosal-associated lymphoid tissue (MALT) lymphoma. It is a gram negative, flexibacteria, oxidase positive, microaerophilic, motile and the only species in the Helicobacter genus to have multiple unipolar – sheathed flagella. Microaerophiles need O₂ because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of O₂. They gather in the upper part of the test tube but not the very top. CO₂ is essential for initial growth of H. pylori in liquid media (microaerophilic property). They produce urease, so it’s a diagnostic tool and not a necessary consideration for cultivation (culture medium).

Explanation

     In myocardial infarction there is necrosis. Nuclear changes in necrosis observed microscopically (light microscope) includes:

·        Karyopicnosis: at first nucleus shrinks and becomes dense.

·        Karyorrhexis: characterized by rupture of nuclear membrane and fragmentation of nucleus. Nucleus is decomposed into small granules.

·        Karyolysis: develops when nucleus dissolves

At electron microscope level, in addition to the above nuclear changes, disorganization and disintegration of the cytoplasmic organelles and severe damage of the plasma membrane are seen.

Explanation

The floor of the urinary bladder houses the trigone of urinary bladder. The trigone lacks the rugae as the submucosa is scarce here and mucosa adheres directly to the muscular layer. The vertices of trigone are related to the ureteric orifices and the internal urethral orifice. It is located at the fundus of bladder – lower wide and dense portion.

Explanation

Hereditary enzymopathy is an inherited inefficiency or lack of enzymes participating in drug metabolism.

Explanation

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

Atrial natriuretic peptide is secreted in response to increase atrial pressure. It causes increase glomerular filtration rate (GFR) and increase sodium ion filtration with no compensatory sodium ion reabsorption and water in distal nephron which leads to increase diuresis.

Explanation

Explanation

Principal complications of peptic ulcer are perforation, penetration, hemorrhage, stenosis, malignization (cancer). Gastric hemorrhage is a very important symptom. It can be manifested by vomiting blood (hematemesis) or by black tarry stools (melena). The vomitus looks like coffee grounds. If hemorrhage is profuse (damage to a large vessel) the vomitus contains much scarlet (unaltered) blood. Hematemesis occurs in peptic ulcer, cancer and polyps, in erosive gastritis etc.

Explanation

The main symptoms of right-sided heart failure are fluid accumulation and swelling (edema) of the feet, ankles, legs, liver and abdomen. Where the fluid accumulates depends on the amount of excess fluid and the effects of gravity. If a person is standing, fluid accumulates in the legs and feet; if a person is lying down, fluid usually accumulates in the lower back; if the amount of fluid is large, fluid also accumulates in the abdomen.

Most water leakage occurs in capillaries or postcapillary venules which have a semipermeable membrane wall that allows water to pass freely than proteins. In cardiac insufficiency, blood pools in the veins since the heart is not pumping effectively; this increases the hydrostatic pressure in the veins. And this increased hydrostatic pressure leads to increase filtration of water into the interstitium at the venous end of the capillary (post-capillary venule).

Explanation

1.     Radiation disease, radiation therapy, chemotherapy or toxic chemicals can destroy megakryocytes. Megakaryocytes are responsible for the production of thrombocytes (platelets) which can lead to thrombocytopenia. Thrombocytopenia is an abnormally low level of platelets in blood, as a result of reduced platelet production in the bone marrow or excessive peripheral destruction of platelets. People with severe thrombocytopenia may have abnormal bleeding (hemorrhagic syndrome) almost anywhere in the body.

Explanation

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

Warfarin inhibits the enzyme vitamin K epoxide reductase. Neonates lack enteric bacteria which produce vitamin K.

Explanation

1.     Barbiturates (Phenobarbital, thiopental) are hypnotics, sedative for anxiety, seizures, insomnia, induction of anesthesia and they induce normal sleep. They have narcotic type of action. Any degree of depression of the CNS is possible, depending on the dose.

Bemegride on the other hand is an analeptic. Analeptics are drugs which act upon the CNS general functions, but stimulates mainly medulla oblongata (respiratory, cardiovascular centers). They can be used in stimulation of respiratory in overdosage or poisoning with narcotic drugs (drugs for general anesthesia, barbiturates).

Both drugs act on CNS but with directly opposite (antagonistic) actions and with a direct action.

Explanation

Hepatoduodenal ligament running from the porta hepatica to the superior part of the duodenum. It consists of double layer of peritoneum and enfolds 3 structures:

·        Common hepatic artery

·        Portal vein

·        Common bile duct

Portal vein is localized posteriorly; hepatic artery – left anterior and bile duct – right anterior.

Explanation

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

* Intrahepatic – blockage of intrahepatic bile ducts

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

Findings:

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

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

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

* Steatorrhea

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

Explanation

     Type IV blood group – AB

Combinative because both alleles of this gene are equally expressed in dominant forms and there is no masking of the characteristics (phenotype) of any of the allele.

Explanation

1.     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

1.     5-6pm

Explanation

RQ = vCO₂   /vO₂ = 800 /1000 (ml) = 0.8

Minute O₂ uptake – 1000ml

    Minute CO₂ emission – 800ml

    Respiratory Quotient (RQ) = vCO₂ /vO₂ = 800/1000(ml) = 0.8

Explanation

1.     The pylorus is a thickened part of the stomach which becomes continuous with the initial part of duodenum. The duodenum begins at the pyloric part of stomach and divided into 4 parts: superior part, descending part, inferior (horizontal) part and the ascending part. The superior part (pars superior) 5cm long, begins from the pylorus and runs horizontally and slightly backwards. On forming the superior duodenal flexure, the intestine passes into the descending part.

Explanation

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

Explanation

The mobilization of stored fat requires the hydrolytic release of fatty acids and glycerol from their triacylglycerol (TAG) form. This process is initiated by hormone-sensitive lipase, which removes a fatty acid from carbon 1 and/or carbon 3 of the TAG. This enzyme is activated when phosphorylated by cyclic AMP (cAMP)-dependent protein kinase. cAMP is produced in the adipocyte when one of several hormones (such as epinephrine or glucagon – stress hormones) binds to receptors on the cell membrane and activates adenylyl cyclase.

Explanation

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

Explanation

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.

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.

Mantoux test is a type IV Hypersensitivity reaction (HSR), which involves macrophages,T-lymphocytes and lymphokines(cytokines). Mononuclear cells (lymphocytes,monocytes,macrophages).

Remember,it is antibody independent (i.e does not involve antibodies).

Explanation

1.     Edema commonly results from increase in hydrostatic pressure or decreased oncotic pressure. With the infusion of different solutions intravenously amounting to 1500ml within 8hours, there is an increase in hydrostatc pressure, which results in the pulmonary edema. The myocardial infarction suffered by the patient aids in the pathogenesis of the pulmonary edema. Pulmonary edema is as a result of left ventricular insufficiency i.e. the myocardial infarction is in the left ventricular myocardium. ↑hydrostatic pressure = ↑volume

Explanation

      The main (primary or first-order) bronchus branches in the hilum of lungs to form the lobar bronchi (secondary), which ventilate the respective lobe. The lobar bronchi in turn branch to form the tertiary (third-order) bronchi called the segmental bronchi. They ventilate the pulmonary areas called segments. Segments are the pyramidal shaped portions of lungs with apices facing the lung root and bases at the lung surface. Each segment excluding the segmental bronchus has a segmental branch of the pulmonary artery respective to segmental bronchi branches. The branches of pulmonary veins run between the segments. Ant segment is surgically removable without major damage to neighboring segments.

Explanation

     Toxoplasma gondi (a protozoa) causes toxoplasmosis, including congenital toxoplasmosis. Tissue cyst (pseudocysts) in undercooked meat or oocyst in cat faeces infects humans. Stages in human most associated with disease includes:

·        Rapidly multiplying trophozoites (tachyzoites) within various cell types.

·        Tachyzoites can pass placenta and infect fetus (congenital toxoplasmosis)

·        Slowly multiplying trophozoites (bradyzoites) in tissue cysts.

Symptomatic and asymptomatic forms of congenital toxoplasmosis should be treated with a combination of sulfadiazine and pyrimethamine/Trimethoprim. Cotrimoxazole is a combination of sulfadiazine + Trimethoprim

Itraconazole – antifungal; Mebendazole – antihelminthic; Azidothymidine and acyclovir – antiviral.

Explanation

         Types of tuberculosis:

o   Primary tuberculosis

o   Post primary tuberculosis: - secondary tuberculosis

   -Hematogenous tuberculosis

            Primary tuberculosis is the infection of an individual who has not been previously infected or immunized. Also called Ghon’s complex or childhood tuberculosis. The primary complex in lungs is usually located in the lower part of the right upper lobes or the upper part of the lower lobes in segments 3,8,9,10. (NB: 8,9,10 segments are in the inferior lobe of the lungs). Primary complex or Ghon’s complex consists of 3 components: pulmonary component; lymphatic vessel component and lymph node component.

            Secondary tuberculosis mainly affects the upper lobes of the lungs.

Explanation

The primary adverse effect of isoniazid is peripheral neuritis, manifesting as paresthesias of the hands and feet. This appears to be due to a relative pyridoxine deficiency.

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

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

Adverse reaction of Isoniazid: peripheral neuritis, optic neuritis, hepatitis and idiosyncratic hepatotoxicity. 

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.

Liposarcoma and fibrosarcoma are malignant with no distinct borders. Angioma is tumor of vessels; Fibroma and Fibrosarcoma are tumors of connective tissue.

Explanation

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

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

Klinefelter – XXY (one barr body)

Turner’s – XO (no barr body)

46 XX is a normal female sex chromosome. All other options are karyotypes for male patients.

Explanation

Acute poststreptococcal glomerulonephritis: most frequently seen in children. Occurs approximately 2 weeks after group A streptococcal infection of pharynx or skin. Resolves spontaneously. Type III hypersensitivity reaction (Immune complex). Presents with peripheral and periorbital edema, cola-coloured urine, hypertension. On immunofluorescent microscopy: granular appearance due to IgG, IgM and C3 deposition along glomerular basement membrane and mesangium. On electron microscopy: subepithelial immune complex humps. On light microscopy: glomeruli enlarged and hypercellular. 

Explanation

Constipations requires the use of laxatives that will stimulate the movement of food through gastrointestinal tract (GIT), produce soft formed stool and accelerate defecation. Bisacodyl is typically prescribed for relief of constipation and for the management of neurogenic bowel dysfunction as well as part of bowel preparation before medical examinations, such as for a colonoscopy. Bisacodyl works directly on the colon to produce bowel movement. It works by stimulating enteric nerves to cause colonic mass movements (contractions); removing the colon hypotonia.

Explanation

Innate or non-specific resistance consist of physical and chemical barriers such as skin, gastric acid, mucus or tears, saliva as well as cells and active mechanisms such as phagocytes, natural killer cells and the complement system. They defend an organism in non-specific form/manner, responding in the same fashion, regardless of what pathogen it is. Examples of physical barriers:

·        Skin: surface is made up of dead skin cells rich in keratin, which impedes microorganisms from entering the body – mechanical barrier

·        Gastric acid is a powerful defense against invading bacteria.

·        Saliva and tears contain antibacterial enzymes such as lysozyme, which destroy the cellular walls of bacteria.

·        Mucus is another defense; coating the mucus membranes and contains IgA antibodies (a component of specific/adaptive immune system).

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

Natrii valproas (sodium valproate) has antiseizure(antiepileptic) activity. It has proved to be the most effective is seizure states with a subcortical focus (e.g. absence seizures). It has also been effective in grand mal seizures but much less effective in partial seizures. It has anticonvulsant, antidepressant, psychotonic (improves psychic conditions) and cardioprotective effects.

Ethosuxemide and Phenobarbital, phenytoin are antiepileptic but no psychotonic effects. Amitriptyline is an antidepressant.

Explanation

Morphine is the major analgesic drug contained in crude opium and is the prototype strong agonist. Morphine and several other opoids have high affinity for μ receptors, whereas other agents have varying affinities for δ and κ receptors. Long term chronic administration can result in physical and psychological dependence (addiction). Withdrawal produces a series of autonomic, motor and psychological responses that incapacitate the individual and cause serious (almost unbearable) symptoms. Repeated use produces tolerance to the respiratory depressant, analgesic, euphoric and sedative effects of morphine. Morphinism is excessive or uncontrolled usage of morphine.

Explanation

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

Explanation

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

All other options are sympathetic effects (acting through α or β-adrenergic receptors).

Explanation

Scabies is a contagious skin disease caused by the itch mite – Sarcoptes scabiei. A person may become infected either by direct contact with a sick individual (including sexual contact) or by indirect one (when the bed clothes, underwear or bed is shared). Commonly the skin eruptions are localized on the interdigital folds of hands, on the lateral surfaces of fingers, flexible surfaces of wrist joint, on the skin of forearms, shoulders, chest, abdomen, buttocks and thighs. Itching is the first and essential symptom of scabies. The pruritic lesions result from a delayed hypersensitivity reaction to the faeces of the mite. The mite is located within the stratum corneum of the epidermis. At the sites of entry and exit of mites double morphologic elements of rash, more often microvesicles, papules, blisters or pustules, multiple scratches and excoriations and small sanguinolent crusts are formed.

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

Explanation

Fibrinopurulent peritonitis: Supurative or purulent inflammation is characterized by the production of large amounts of pus. The cellular inflammatory response in peritoneal cavity is composed primarily of dense collections of neutrophils and fibrinopurulent debris that coat the visceral and abdominal wall. Serous peritonitis – thin fluid (not pus);

Hemorrhagic peritonitis  - hemorrhage; Tuberculous peritonitis – the patient must have TB, before there can be an extrapulmonary TB.

Explanation

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

Cancer of any of the following will metastasize locally through:

            Submandibular salivary gland – submandibular nodes

            Thyroid gland – deep anterior cervical nodes

            Stomach – celiac nodes

            Lungs – visceral thoracic lymph nodes

Explanation

Saliva contains two major types of protein secretion:

·        A serous secretion that contains ptyalin (α-amylase or salivary amylase), an enzyme for digesting starches.

·        Mucus secretion that contains mucin for lubricating and for surface protective purposes.

Salivary amylase is a carbohydrate-digesting (amylolytic) enzyme. It acts on cooked or boiled starch and converts it into dextrin and maltose. Though starch digestion starts in the mouth, major part of it occurs in stomach because food stays only for a short time in the mouth. Optimum pH necessary for the activation of salivary amylase is 6. Salivary amylase cannot act on cellulose.

Explanation

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

Explanation

The main symptoms of right-sided heart failure are fluid accumulation and swelling (edema) of the feet, ankles, legs, liver and abdomen. Where the fluid accumulates depends on the amount of excess fluid and the effects of gravity. If a person is standing, fluid accumulates in the legs and feet; if a person is lying down, fluid usually accumulates in the lower back; if the amount of fluid is large, fluid also accumulates in the abdomen.

Most water leakage occurs in capillaries or postcapillary venules which have a semipermeable membrane wall that allows water to pass freely than proteins. In cardiac insufficiency, blood pools in the veins since the heart is not pumping effectively; this increases the hydrostatic pressure in the veins. And this increased hydrostatic pressure leads to increase filtration of water into the interstitium at the venous end of the capillary (post-capillary venule).

Explanation

 Myasthenia gravis is an autoimmune disease of neuromuscular junction caused by antibodies to cholinergic receptors. It is characterized by grave weakness of the muscle due to the inability of neuromuscular junction to transmit impulses from nerve to the muscle. It is caused due to the development of auto-antibodies (IgG auto-antibodies) against the receptors of acetylcholine. That is, the body develops antibodies against its own acetylcholine receptors. These antibodies prevent binding of acetylcholine with its receptors or destroy the receptors. So, though the acetylcholine release is normal, it cannot execute its action.

Explanation

Pernicious anemia or addison’s anemia is the anemia due to deficiency of vitamin B₁₂. It is due to atrophy of the gastric mucosa (atrophic gastritis) because of autoimmune destruction of parietal cells. The gastric atrophy results in decreased production of intrinsic factor and poor absorption of vitamin B₁₂, which is the maturation factor for red blood cells (RBC). RBCs are larger and immature with almost normal or slightly low hemoglobin level. Synthesis of hemoglobin is almost normal in this type of anemia. So, cells are macrocytic and normochromic/hypochromic.

Explanation

Skin cancer (epithelial tumors) is divided into 4 groups:

·        Intraepidermal cancer (cancer in situ): Bowen’s disease, erythroplasia of Queyrat.

·        Basal cell carcinoma (BCC, basalioma)

·        Epidermoid cancer

·        Skin appendage cell carcinoma: Paget’s disease

Basal cell carcinoma (basalioma) is malignant; the tumor is characterized by slow growth (sometimes for years), locally destructive invasive growth without metastases and frequent recurrences. The tumor is of polymorphous structure derived from the epidermis and skin appendages. The most prevalent location is the face, neck and scalp. Gradually increasing in size, they can form a large plaque or node with ulcerative depression in the center and elevated borders. It has the appearance of a flat well-defined reddish, round or oval-shaped spot or plaque.

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

K⁺ sparing diuretics:

  - aldosterone antagonist: spironolactone, eplerenone

  - inhibit Na⁺ reabsorption: triamterene

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

     Carbonic anhydrase inhibitor: acetazolamide; Thiazide diuretics: hydrochlorthiazide; Loop diuretics: furosemide

Explanation

Stages of atherosclerosis:                                                                                    àPre-lipid stage: mucoid swelling  of intima, destruction of endothelium, elastic & collagen fibres of intima’s basal membrane.

àStage of fatty stripes (lipidosis):  Fatty stripes appear on intima. Macrophages that have accumulated lipid in their cytoplasm appear as csantomic or foam cells.                                                                                      

 àStage of liposclerosis: Lipid accumulates  not only in macrophages but also in smooth muscle cells. In areas of lipidosis (lipid core), a young CT grows & forms a fibrous cap/plaque.                                                       

 àStage of atheromatosis: Necrosis of central part of fibrous cap, with formation of atheromas. Atheromas consist of  amorphous lipid-rich material & are soft.                                                                                             

 àStage of ulceration: Break of fibrous cap cover & ulceration with small hemorrhage into plaque.                                                                                     

àStage of atherocalcinosis: Deposition of calcium in ulcerative plaque. Calcification of vessels leads to hardening of arteries, which appears white & petrosal.

Only stage of liposclerosis and atherocalcinosis have been mentioned in Krok so far.

Explanation

The hallmark and earliest feature of chronic bronchitis is hypersecretion of mucus in large airways and is associated with hypertrophy of the submucosal glands in the trachea and bronchi. As chronic bronchitis persists, there is also a marked increase in goblet cells of small airways leading to excessive mucus production that contributes to airway obstruction. Histological features of the small airways:

·        Goblet cell metaplasia with mucus plugging of the lumen.

·        Inflammatory infiltration

·        Fibrosis of bronchiolar wall (granulation tissue)

·        Atypical metaplasia and dysplasia of the respiratory epithelium, providing a possible soil for cancerous transformation.

Explanation

     Acute tubular necrosis/Necrotic nephrosis/Necronephrosis involves the death of tubular epithelial cells that form the renal tubules of the kidneys. Most common cause of acute renal failure. It can be ischemic or nephrotoxic.

·        Ischemic acute tubular necrosis occurs due to hypoperfusion of the kidneys.

·        Nephrotoxic acute tubular necrosis occurs as a result of direct damage to tubular cells by ingestion, injection or inhalation of a number of toxic agents. Toxic agents causing nephrotoxic acute tubular necrosis includes mercuric chloride, ethylene glycol, carbon tetrachloride etc.

Macroscopically, the kidneys are enlarged and swollen (edematous). On cut section, the cortex is pale, while the medulla is slightly darker than normal. The capsule can be easily removed.

Explanation

Osteolaterism results in conditions of deficiency or non-functional lysyl oxidase. Lysyl oxidase is involved in the cross-linking of elastin and collagen resulting in disorganized connective tissue formation. Lysyl oxidase is an extracellular copper enzyme that catalyzes formation of aldehydes from lysine residues in collagen and elastin precursors. This results in cross-linking collagen and elastin, which is essential for stabilization of collagen fibrils and for the integrity and elasticity of mature elastin.

Explanation

The nephron consists of the renal corpuscle and a tubule system. The renal corpuscle represents the beginning of the nephron. It consists of the glomerular capillary tuft which possesses numerous fenestrations and the surrounding visceral and parietal epithelial layers (bilayer) of Bowman’s capsule. Bowman’s capsule is the initial portion of the nephron where blood flowing through the glomerular capillaries undergoes filtration to produce the glomerular ultrafiltrate.

Explanation

Magnesium sulfate reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholine release at the neuromuscular junction. Magnesium is a unique calcium antagonist as it can act on most types of calcium channels in vascular smooth muscle and as such would be expected to decrease intracellular calcium. One major effect of decreased intracellular calcium would be inactivation of calmodulin-dependent myosin light chain kinase activity and decreased contraction, causing arterial relaxation that may subsequently lower peripheral and cerebral vascular resistance, relieve vasospasm and decrease arterial blood pressure. Therefore, it is recommended that intravenous calcium gluconate or calcium chloride should be available as an antagonist of magnesium to increase intracellular calcium level.

Explanation

Shock is a form of stress which is accompanied by the release of stress hormones (catecholamines, cortisol). Stress-induced changes in blood leukocyte distribution may represent an adaptive response. This represents a redistribution of leukocytes from the blood to other organs such as the skin, draining sentinel lymph nodes and other compartments. Such leukocyte redistribution may enhance immune function in compartments to which immune cells traffic during stress.

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.

Calcitonin is secreted by parafollicular cells (C cells of the thyroid gland). It ↓bone resorption of Ca²⁺. It opposes actions of parathyroid hormone. But its not important in normal Ca²⁺ homeostasis. Calcitriol ↑ circulating Ca²⁺ ions as a means of enhancing intestinal absorption of calcium (NB: Calcitriol production is dependent on parathyroid hormone).

Therefore hypoparathyroidism results in hypocalcemia and hyperphosphatemia.

Explanation

Pirogov’s stages of shock

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

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

Explanation

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

* nondisjunction (maternal and paternal nondisjunction in meiosis I)

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

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

Explanation

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

Explanation

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

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

Explanation

Aminoglycoside binds the 30S ribosomal subunit and interferes with assembly of the functional ribosomal apparatus and/or can cause the 30S subunit of the completed ribosome to misread the genetic code. The elderly are particularly susceptible to nephrotoxicity and ototoxicity as an adverse effect of aminoglycosides. Ototoxicity (vestibular and cochlear) is directly related to high peak plasma levels and the duration of treatment. The antibiotic accumulates in the endolymph and perilymph of the inner ear and toxicity correlates with the number of destroyed hair cells in the organ of corti. Deafness may be irreversible and has been known to affect fetuses in utero.

Explanation

The thymus resides in the anterior mediastinum posterior to the manubrium of sternum reaching the IV rib. Mediastinal pleurae neighbor the thymus laterally, the pericardium, arch of aorta with associated branches and inferior vena cava posteriorly. Topographically, the thymus is closer to the sternum than the heart. So it will be affected first by a blow to the sternum because it lies outside of the pericardial cavity (anterior to the fibrous pericardium).

Explanation

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

Explanation

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

Parietal (oxyntic) cells are found in the neck of the fundic glands, among the mucus neck cells and in the deeper part of the gland. They secrete HCl and intrinsic factor. When examined with the transmission electron microscope they are seen to have an extensive intracellular canalicular system that communicates with the lumen of the gland. Also an elaborate tubulo-vesicular membrane system is present in the cytoplasm adjacent to the canaliculi. Numerous mitochondria with complex cristae and many matrix granules supply the high levels of energy necessary for acid secretion.

Explanation

Energy supply to any cell is provided by ATP. Nitroglycerine relieves stenocardia by causing vasodilation thereby increasing blood supply locally to the myocardium. This increase in blood supply, increases the supply of substrates needed to make ATP. Therefore, a dose of Nitroglycerine → ↑blood supply → ↑substrates for ATP synthesis → ↑intensification of ATP synthesis.

Explanation

The main reasons for hypercalcemia are primary hyperparathyroidism (which can result from adenoma of parathyroid gland), hypervitaminosis D (calcium absorption in the intestine increases). Hypercalcemia often accompanies difficult fractures and this numerous fractures violate the equilibrium between bone construction processes, which sharply decreases and the resorption, which continues with previous speed. Reklinghausen described development of osteodystrophy as the result of bone decalcinosis at the continuous hyperparathyroidism (parathyroid adenoma). NB: parathyroid hormone → ↑bone resorption. This disease is characterized by gradual dilution and softening of bones. Metabolic osteoclasts activity increases due to the action of parathormone. Loss of bone matrix occurs and the bone becomes soft. Resorption allotments are replaced with fibrous connective tissue and zones of osteoid substance are formed.

Explanation

Lordosis is an exaggerated anterior curvature of the spine, most often lumbar. Lordosis is present in the cervical and lumbar regions (cervical and lumbar lordoses). The intervertebral synchondroses and symphyses are reinforced by the longitudinal ligaments which run along the entire spine.

·        *Anterior longitudinal ligament is a band which extends from the atlas to the pelvic surface of the hip bone along the anterior surfaces of the vertebral bodies.

·     *Posterior longitudinal ligament runs along the posterior surface of the vertebral bodies (in the vertebral canal).

Therefore, a damage to the anterior longitudinal ligament can induce lordosis.

Explanation

When water or any irritating noxious vapors or gases affects the mucus membrane of the nose, an involuntary temporary arrest of breathing (apnea) develops. This is a protective reflex to prevent the subject from inhaling harmful substances (reflectory apnea – reflex apnea).

Explanation

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

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

                  *Cytokinesis – division of the cell into two daughter cells.

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

Explanation

X-linked (Bruton) agammaglobulinemia: defect in Bruton’s tyrosine kinase (BTK), a tyrosine kinase gene → no B cell maturation. X-linked recessive (↑in boys). Findings: absent B cells in peripheral blood, ↓immunoglobulin of all classes. Absent/scanty lymph nodes and tonsils.

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

Action potential is a series of electrical changes that occur in the membrane potential when the muscle or nerve is stimulated. It occurs in 2 phases: depolarization and repolarization. Excitable tissues obey the all-or-none law which states that when an excitable tissue is stimulated by a stimulus, it gives maximum response or does not give any response at all. Below the threshold level i.e. if the strength of stimulus is not adequate, the tissue does not give any response. Action potential obeys the all-or-none law because a particular threshold must be reached for an action potential to occur.

Explanation

Some other options listed are opoid analgesics; but Promedol remains the best answer because it has a spasmolytic effect (antispasmodic). Therefore, it is very effective for pains associated with spasms of smooth muscles of internal organs and blood vessels. In comparison with morphine hydrochloride, it has less oppressing activity on respiratory centers, less than excites the center of the vagus nerve and the vomiting center. When the pain is associated with spasms of smooth muscle (angina pectoris, liver, kidney, intestinal cramps) you can assign promedol with atropine, metacin, papaverine etc.

Explanation

Septicemia is a form of sepsis. Hemorrhagic syndrome is well pronounced (petechial rash, hemorrhages to the serous and mucus membranes and internal organs, DIC). Hyperplasia of lymphoid and hemopoietic system is typical. Proliferation of lymphoid and reticular cells as well as accumulation of mature and immature blood cells are found in the spleen and lymph nodes. Interstitial inflammation develops  in the parenchymal organs (heart, liver, kidneys). Septicemia can lead to septic shock. DIC – disseminated intravascular coagulation

Explanation

Fasciculus gracilis (tract of Goll) and Fasciculus cuneatus (tract of Burdach): fasciculus gracilis and cuneatus are together called ascending posterior column tracts. These tracts are formed by the fibers from posterior root ganglia. Thus, both tracts are constituted by the fibers of first order neurons of sensory pathway. Functions: fine (epicritic) tactile sensation; tactile localization; tactile discrimination; sensation of vibration; conscious kinesthetic sensation; stereognosis (ability to recognize the known objects by touch with closed eyes).

Fasciculus gracilis contains the fibers from lower extremities and lower parts of the body. Fasciculus cuneatus contains fibers from upper part of the body.

Explanation

The citric acid cycle (kreb’s cycle, TCA cycle) is a good example of amphibolic pathway. The first reaction of the cycle in which oxaloacetate (4 carbon compound) condenses with acetate (2 carbon compound) to form citrate (6 carbon compound) is typically anabolic. The next few reactions which are intramolecular rearrangements produce Isocitrate. The following two reactions are typically catabolic. ‘COO’ is lost in each step and succinate (4 carbon compound) is produced. Amphibolic involves both catabolism and anabolism.

Explanation

Metaplasia is a reversible change of one type to another type of adult epithelial or mesenchymal cells, usually in response to abnormal stimuli and often reverts back to normal on removal of stimulus. Types (2):

·        Epithelial: *Squamous metaplasia: in bronchus (chronic smokers), cervix

  *Columnar metaplasia: there is transformation to columnar epithelium.

·        Mesenchymal metaplasia: osseous and cartilaginous.

Hyperplasia: ↑number of cells; Hypertrophy: ↑in size.

Explanation

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

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

Explanation

Extrasystole is the premature contraction (an extra contraction) of the heart before its normal contraction. In other words, it is an extra contraction of the heart before its normal contraction. It is caused by an ectopic focus (discharge of an impulse from any part of the heart other than the Sinoatrial node).

Bradycardia: ↓heart rate; Tachycardia: ↑heart rate; Flutter: rapid heart contractions; Fibrillation: very rapid heart contractions. (In all this, there is no extra heart contraction, we just have faster contractions).

Explanation

Administered nitrates → ↑ Nitrites →↑ Nitric oxide (NO) → ↑cGMP → ↑dephosphorylation of myosin chains → vascular smooth muscle relaxation. Nitroglycerin is an organic nitrates. Nitrates inhibit coronary vasoconstriction or spasm, increasing perfusion of the myocardium and thus relieving vasospastic angina. Because of this action, nitrates are effective in treating effort-induced (stress) angina. Classic, effort-induced or stable angina are experienced in such conditions as physical activity, emotional excitement or any other cause of increased cardiac workload.

Explanation

All muscles that elevate the rib cage are muscles of inspiration and those that depress the rib cage are muscles of expiration.

Muscles of inspiration:

·        Sternocleidomastoid: lift upward on the sternum.

·        Anterior serrati: lift many of the ribs.

·        Scalene: lift the first two ribs.

Muscles of expiration: Abdominal recti – pull down the lower ribs and other abdominal muscles also compress the abdominal contents upwards against the diaphragm and internal intercostals.

Normal respiration is accomplished by the movement of the diaphragm only.

Explanation

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

Explanation

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

All other options are sympathetic effects (acting through α or β-adrenergic receptors).

Explanation

Explanation

In viral hepatitis, there is generalized liver dysfunction involving uptake and conjugation of unconjugated bilirubin, secretion of conjugated bilirubin into bile ducts, and recycling of urobilinogen. Alanine transaminase (ALT) and Aspartate transaminase (AST) are increased (↑), but ALT is higher than AST and there is a slight ↑ in alkaline phosphatase (ALP) and ɣ-glutamyltransferase (GGT).

ALT is a specific enzyme for liver necrosis; present in the cytosol. ALT>AST: viral hepatitis.

AST is present in the mitochondria. Alcohol damages mitochondria AST>ALT indicates alcoholic hepatitis

Explanation

Explanation

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

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

Explanation

Liver is the primary organ of protein synthesis. In a case of dysfunction of protein synthesis, hypoproteinemia occurs. We have absolute and relative hypoproteinemia. Absolute is when there is disturbed synthesis (absolute hypoproteinemia) and in cases of increased synthesis (absolute hyperproteinemia); while relative does not have to do with synthesis but other pathologies e.g. renal lesions, in which case, there is loss of protein with urine (relative hypoproteinemia); also vomiting, diarrhea, profuse sweating can produce relative hyperproteinemia.

Explanation

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

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

Explanation

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

*       * Antibodies to DNA

·       * Antibodies to histones

·        *Antibodies to nonhistone proteins bound to RNA

·        *Antibodies to nuclear antigens.

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

Explanation

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

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

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

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

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

Explanation

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

Explanation

In laboratory diagnosis of tuberculosis, the nature of specimen depends on the site of lesion. In pulmonary tuberculosis, 3 specimens are investigated – sputum, laryngeal swab and gastric savage. Direct microscopy of a suitably stained Ziehl Neelson smear may reveal the presence of tubercle bacilli. The sputum for microscopy should always be subjected to concentration method which serves 3 purposes – concentration, homogenization and decontamination. Petroff’s method using caustic soda (4%) yields good results.  Homogenization may also be done by sulphuric acid, oxalic acid or trisodium phosphate.

Explanation

Alveolar epithelium is composed of type I and II alveolar cells and occasional brush cells. Type II alveolar cells or type II pneumocytes or septal cells are secretory cells. Their apical cytoplasm is filled with granules as stacks of parallel membrane lamellae, the lamellar bodies. They are rich in a mixture of phospholipids, neutral lipids and proteins that is secreted by exocytosis to form an alveolar lining, surface-active agent called surfactant.

Explanation

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

Explanation

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

Polycythemic hypovolemia is a condition with a decreased amount of plasma usually characterized by appreciable concentration and increased viscosity of blood. Hematocrit is above normal. This condition is observed in connection with considerable loss of water by the organism as in diarrhea, intractable vomiting, extensive burns. Hematocrit is increased because there is no loss of erythrocytes just fluid was lost from vomiting. It can’t  be hypervolemia because there is loss of fluid from prolonged vomiting.

In simple hypovolemia: hematocrit is normal; oligocythemic hypovolemia: hematocrit is decreased.

Explanation

Vibrio cholera is the cause of cholera. It is curved, comma-shaped, gram negative rods. It is transmitted by fecal contamination of water and food, primarily from human sources. Clinically, watery diarrhea in large volumes is the hallmark of cholera. There are no red blood cells or white blood cells in the stool. Rice-water stool is the term often applied to the non-bloody effluent. Grows in an alkaline media. Dark-field and phase contrast microscopy have been used for screening fecal specimens for the presence of V. cholera. With these techniques, liquid stools are microscopically examined for the presence of organisms with typical darting (“shooting star”) mobility [analogous to ‘hanging drop’].

Explanation

Fontanelles are large fibrous areas where several sutures meet; often called “soft spots” on an infant’s head. The two largest fontanelles are the anterior and posterior fontanelles on the superior surface of the neurocranium. The fontanelle in the back of the head (posterior fontanelle) usually closes by the time an infant is 2-3 months old. The fontanelle at the top of the head (anterior fontanelle) usually closes between 7-18months. In adults the remnants of the anterior fontanelle is the bregma and the posterior fontanelle is the lambda.

Explanation

Mantoux test is a type IV Hypersensitivity reaction (HSR), which involves macrophages,T-lymphocytes and lymphokines(cytokines). Mononuclear cells (lymphocytes,monocytes,macrophages).

Remember,it is antibody independent (i.e does not involve antibodies).

B-lymphocytesàPlasma cellsàIg(Antibodies)------- none is involved in Type IV HSR.

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.

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

Serotonin, also called 5-hydroxytryptamine, is synthesized and stored at several sites in the body. It can be found in the intestinal mucosa, central nervous system and in platelets. Serotonin is synthesized from tryptophan, which is hydroxylated. The product, 5-hydroxytryptophan is decarboxylated to serotonin, which is also degraded by monoamine oxidase (MAO). Serotonin has multiple physiologic roles, including pain perception, affective disorders, and regulation of sleep, temperature and blood pressure.

Explanation

Mesenchyme refers to loosely organized embryonic connective tissue regardless of origin. Undifferentiated embryonic mesenchymal cells are round/cuboidal in shape. During development, visceral myogenesis is shortly preceded by mesenchymal cell elongation. Undifferentiated embryonic mesenchymal cells from intestine (abundant visceral muscle), lung (some visceral muscle) or kidney (no visceral muscle); these cells differentiate into smooth muscle upon elongation.

Explanation

In meiosis, two members of a pair of homologous chromosomes normally separate during the first meiotic division, so that each daughter cell receives one member of each pair. Sometimes, however, separation does not occur (nondisjunction) and both members of a pair move into one cell. As a result of nondisjunction of the chromosomes, one cell receives 24 chromosomes and the other receives 22 instead of the normal 23. When at fertilization, a gamete having 23 chromosomes (spermatozoon) fuses with a gamete having 24 or 22 chromosomes, the result is an individual with either 47 chromosomes (47 XXX – trisomy X) or 45 chromosomes (45 XO – monosomy X, Turner’s syndrome). In women, the incidence of chromosomal abnormalities including nondisjunction, increases with age especially at 35years and older.

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

His condition became worse after taking antipyretic drug. Antipyretic drugs block prostaglandin synthesis by inhibiting cyclooxygenase (COX) enzyme at the thermoregulating centers in the hypothalamus and at peripheral target sites. In case of toxicity of this drug, it can result in coma followed by cardiovascular collapse and respiratory arrest due to its CNS depressant activity. Consciousness is confused; arterial blood pressure is low and pulse rate is very high – these are clear signs of collapse.

Explanation

Cerebral cortex consists of gray mater that surrounds the deeper white mater. The cerebral cortex is formed by 6 layers of structures:

·        Molecular or plexiform layer or horizontal layer ( contains horizontal cells of cajal).

·        External granular/stellate layer

·        Outer pyramidal layer

·        Internal granular/stellate layer

·        Internal pyramidal layer

·        Fusiform cell layer

Layers of grey mater in cerebellum:

·        Outer molecular or plexiform layer

·        Intermediate purkinje layer

·        Inner granular layer

Explanation

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

Explanation

Streptococcus mutans are gram positive cocci shaped bacteria. They are facultative anaerobes and a major contributor of tooth decay. It’s a cariogenic microorganism that breaks down sugar for energy and produces an acidic environment which demineralizes the superficial structure of the tooth. The result of the conversion disintegrates the coating of the tooth then later dissolves the calcium molecule creating a hole. Transmission of S. mutans can be found in people of all ages although it is more common for infants and children. Since every human has bacteria in their mouth, the only prevention is to lessen the impact of acid fermentation by practicing adequate oral hygiene.

Explanation

Explanation

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

·        Superior: Teres minor

·        Inferior: Teres major

·        Medial: Long head of triceps

·        Lateral: humerus