practice

Explanation

Acute poisoning with narcotic analgesics (e.g. morphine) is characterized by sleep or unconsciousness, normal or increased reflexes, normal muscle tone, miosis, bradycardia, cheyne-stokes breath, the retention of urine, a spasm of intestine and bowel. This condition can be treated with:

·        Stomach lavage with 0.5% solution of potassium permanganate.

·        Intravenous injection of Naloxone (naloxone is an antagonist of narcotic analgesic).

·        Atropine; for decrease in the vagal action of morphine.

Explanation

          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

        Loratadine is an antihistamine (antiallergic drug) which refers to the classic H₁-receptor blocker. These compounds do not influence the formation or release of histamine. Rather, they block the receptor-mediated response of a target tissue. They are much more effective in preventing symptoms than reversing them once they have occurred. These agents, desloratadine, fexofenadine, and loratadine show the least sedation i.e. least effect on CNS (they don’t induce sleep).

Explanation

Dithyllium is a depolarizing myorelaxant (neuromuscular blocking drug). They are used as adjuvant drugs in anaesthesia during surgery to relax skeletal muscles. An absence or deficiency of acetylcholinesterase/pseudocholinesterase enzyme leads to a silent condition that manifests itself only when people that have the deficiency receive the muscle relaxants. This enzyme plays an important role in  the metabolism of ester-based local anesthesics, a deficiency of blood cholinesterase can prolong the effect of dithylinium from just 5-7minutes to 8hours.

[Wherever Butyrylcholinesterase occurs in the option along with Acetylcholinesterase; butyrylcholinesterase is the right option in krok]

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.

3-hydroxyanthranilic acid is an intermediate in the metabolism of tryptophan.

Explanation

The last two steps in uric acid biosynthesis is catalyzed by xanthine oxidase.  Deficiency of this enzyme can lead to reduction in the uric acid concentration.

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

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

Explanation

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

Explanation

One of the laboratory tests for diabetes mellitus is the level of glycosylated hemoglobin. Glycosylated hemoglobin test (HbA_1C, glycohemoglobin) are proteins with glucose bound to them by nonenzymatic way. They precisely represent the extent of impairment of the carbohydrate metabolism and serve as the basic index of quality of compensation of diabetes mellitus. The level of HbA_1C is determined by the method of chromatography using special laboratory equipment. Level of HbA_1C shows an average blood concentration during the previous 2 - 3 months. Normal level of HbA_1C is 4 – 6%. [4 – 8 weeks (1-2months)]

Explanation

The inferior mesenteric artery arises from the anterior aspect of the abdominal aorta. The artery gives the branches as follows: left colic artery (arteria colica sinistra); sigmoid arteries (supplies sigmoid colon) and superior rectal artery (supplies the rectum). Left colic artery (sinister colic) ascends leftwards to supply the descending colon. On reaching the intestine, the artery gives the ascending and descending branches that anastomose with the middle colic artery and sigmoid artery.

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

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

Explanation

Chingamin (chloroquine) prevents polymerization of the hemoglobin breakdown product (heme) into hemozoin. Intracellular accumulation of heme is toxic to the parasite. It is a weak base and may buffer intracellular pH, thereby inhibiting cellular invasion by parasitic organisms. The drug is solely a blood schizonticide (erythrocytic) and will not eradicate secondary tissue schizonts. It is the drug of choice for acute attacks, prophylaxis and treatment of malaria, has been used in amebic liver disease in combination with metronidazole and in autoimmune disorders including rheumatoid arthritis, systemic lupus erythematous (interstitial disease).

Explanation

Deficiency of UGT inhibits conjugation and therefore increase unconjugated bilirubin in serum (Jaundice).

Explanation

Glucocorticoids (prednisolone) stimulate gluconeogenesis. As a result, blood sugar rises, muscle protein is catabolized and insulin secretion is stimulated. Corticosteroids cause increased gluconeogenesis, increased lipolysis, CNS effects - at times including euphoria, maintenance of cardiovascular function by potentiation of norepinephrine. Gluconeogenesis uses the reversible reactions from glycolysis and 4 distinct reactions that circumvent the ones from glycolysis that are irreversible. These reactions are catalyzed by pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1, 6-bisphosphatase and glucose-6-phosphatase. Glucagon, epinephrine and glucocorticoids stimulate all these enzymes (excluding pyruvate carboxylase).

Explanation

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

Explanation

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

The walls of the tympanic cavity (6): tegmental wall, jugular wall, labyrinthine wall, membranous wall, carotid wall and mastoid wall. The mastoid wall (paries mastoideus) is the posterior wall related to the mastoid process of temporal bone. The opening on the wall – the aditus, to mastoid antrum leads to the greatest air cell called the mastoid antrum (antrum mastoideum) and further to smaller mastoid air cells.

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

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

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

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

Explanation

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

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

Explanation

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

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

Explanation

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

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

Explanation

Hepatic steatosis can occur when humans are deprived of choline.

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

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

Explanation

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

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

Explanation

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

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

Myeloma/Plasmocytoma/Multiple Myeloma

Explanation

Vitamin B6 (pyridoxine): coenzyme forms – Pyridoxal phosphate (PALP)

                                                                        - Pyridoxamine Phosphate (PAMP)

Components of pyridoxal enzymes used in transamination (e.g. ALT and AST); decarboxylation reactions, glycogen phosphorylase, transformation of tryptophan to Niacin (Vit B3), active transport of amino acids through the cell membrane, synthesis of cystathionine, heme, histamine and neurotransmitters including serotonin, epinephrine, norepinephrine, dopamine and GABA.

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

     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

The facial nerve (CNVII) comprises mostly the motor fibers that arise from the motor nucleus of facial nerve. These fibers supply the facial muscles. The following branches supply the mimic muscles: temporal, zygomatic, buccal, marginal mandibular and the cervical branches. Clinical applications: conductivity disorders in the facial nerve result in paralysis of the facial muscles. This may be caused by chilling (cold) that develops into neuritis. The state is manifested by facial asymmetry. The patient cannot close the eyes and raise the eyebrows – as a result of temporal branch defect that supplies orbicularis oculi; cannot bare his teeth – as a result of marginal mandibular branch defect that supplies the mental and oral muscles.

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).

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

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

Explanation

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

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

·        Inflammatory disease  like skin infections, organ abscesses

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

·        MRSA (methicillin-resistant Staphylococcus aureus) infection.

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

Explanation

Palmar interosseous muscles: adduction of the digits to the axial line/midfinger (finger III)

Dorsal interosseous muscles: abduction of the digits from the axial line.

Explanation

Explanation

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

·        Erythrocytic membrane structure (membranopathy)

·        Erythrocytic enzyme activity (enzymopathy)

·        Structure or rate of hemoglobin synthesis (hemoglobinopathy)

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

o   Hereditary spherocytosis (Minkowsky-shauffard disease)

o   Hereditary elliptocytosis (ovalocytosis)

o   Hereditary pyropoikilocytosis

o   Hereditary and acquired stomatocytosis

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

Explanation

Explanation

All options listed are all 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

Explanation

Microscopic examination of specific granulomas:

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

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

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

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

Explanation

Explanation

            Pressure in each heart chambers:

Only the left ventricle can range from 0-120mmHg

Explanation

Diffuse cardiosclerosis

Diffuse – multiple whitish layers of connective tissue

Cardiosclerosis – Atherosclerotic calcified plaques

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

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

Explanation

The enzymatic components of gastric juice of the child is similar to the component of the adult person, however, it considerably differs according to age. After the birth of the child, the gastric juice is secreted in very little amount (about 20ml) and its acidity is low, the splitting of protein by pepsin is absent. It gradually develops up to the end of the first year of life when pH decreases (i.e. ↑acidity). However, the splitting of protein in the stomach appreciably occurs. It is promoted by the enzyme called rennin, which curdles milk into fine flakes. Rennin operates the best way in poorly acidic environment (pH 6 – 6.5), but it can also function in neutral and weak alkaline environment.

NB: Renin – kidney;  Rennin – stomach

Explanation

The most common complication of insulin therapy is hypoglycemia. For treatment of hypoglycemia:

·        Intravenous injection of glucose solution 500 – 5%

·        Subcutaneous injection of glucagon 1.0ml

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

Explanation

There are nine flexor tendons in the carpal tunnel. The flexor tendons of the fingers, the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP), are arranged in the carpal tunnel, superficial and deep respectively and continue distally in pairs to each finger except the thumb. They are invested by a common tendon sheath that starts proximal to the carpal tunnel and extends to within 5mm of the insertion of the profundus tendon on the distal phalanx. A separate ulnar bursa envelops the flexor tendons of the little finger (digiti minimus). The other tendon in the carpal tunnel is the flexor tendon of the thumb, flexor pollicis longus, which has a separate synovial covering the radial bursa. There is a gap between ulnar bursa and the synovial sheaths of the index, long (digiti medius), and ring (digiti anularis) fingers in the distal palm of the hand, therefore inflammation cannot spread to this 3 fingers directly from the common synovial sheath.

The flexor pollicis longus is surrounded by the radial bursa, which extends distally. The other flexor tendons are surrounded by the ulnar bursa, which extends to the little finger (digiti minimus). Note the gap between this bursa and the synovial sheaths of the 2^nd, 3^rd and 4^th fingers. The little finger will most probably be damaged.

Explanation

The diagnosis of localized infections depends on gram staining and culture of the discharge which is then viewed under the microscope. In men, the finding of gram negative diplococci within polymorphonuclear leukocytes in a urethral discharge specimen is sufficient for diagnosis. But in women, the use of gram stain alone can be difficult to interpret, therefore cultures should be done. The specimen is cultured on Thayer-Martin medium. Gram stains on cervical specimens can be falsely positive because of the presence of gram negative diplococci in the normal flora and can be falsely negative because of the inability to see small number of gonococci when using the oil immersion lens (in oil immersion microscope).

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

Influenza is an acute respiratory viral infection. The clinical-morphological forms of influenza are slight influenza, mild influenza and severe influenza. The histopathologic features of mild influenza include a necrotizing tracheitis and bronchitis; diffuse hemorrhagic necrotizing pneumonitis with pulmonary edema. Pulmonary complications in severe influenza: lungs are dark and firm with interstitial emphysema (enlarged lungs); necrotic foci; abscesses; lungs appear as “large variegated (motley) influenza lung.” Obliterating bronchitis, bronchiolitis, bronchiectasis and other chronic lung diseases can develop.

Explanation

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

 Benzylpenicillin sodium is a short acting penicillin.

Explanation

Explanation

Chorioepithelioma or choriocarcinoma or gestational choriocarcinoma is a malignant neoplasm of trophoblastic cells derived from a previously normal or abnormal pregnancy. NB: trophoblast differentiates into 2 layers (cytotrophoblast and syncytiotrophoblast) in the 2^nd week of development of an embryo. Chorioepithelioma is a soft, fleshy, yellow-white tumor that usually has large pale areas of necrosis and extensive hemorrhages. Histologically, it does not produce chorionic villi and consists entirely of proliferating syncytiotrophoblasts and cytotrophoblasts.

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

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

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

Explanation

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

Explanation

There is a certain correlation between age of individual and thymus activity. In neonates, it already appears to have a considerable mass of 13.3g on the average. Most intensive growth occurs during first 3years of life, when the gland doubles in size. Having reached the maximum weight (about 26 – 30g), the thymus retains it until 20years of life. After 20 years of age, the thymus parenchyma experiences gradual involution and is substituted with fat tissue. After 50 years of age, the fat constitutes 90% of gland mass.

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

Serological reactions or tests are carried out on a sample of blood serum which is used to detect serum antibodies or antibody-like substances that appear specifically in association with certain diseases. Types:

* Neutralization reaction: depend on capacity of antibody to neutralize infectious properties of infectious organisms. If the antibody is present to botulinum toxin, it confirms the diagnosis. It shows that the body has developed antibodies against the antigen (botulinum toxin). A patient who is not infected will not have the antibody.

* Precipitation reaction: takes place when the antibody and specifically prepared antigens are mixed together.

Explanation

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

Factor II – Prothrombin

Factor VII – Stable factor

Factor IX – Christmas factor

Factor X – Stuart-Prower factor

Deficiency of vitamin K → ↓clotting factors → prolongation of coagulation time → hemorrhages.

Explanation

The symptoms describe cardiac insufficiency. Cardiac glycoside is the most appropriate in this case. Cardiac glycosides are glycosidic drugs of plant origin having cardiac inotropic property, increase myocardial contractility and output.

Digitoxin is long-acting but basically administered orally and used mainly for chronic heart failure (also digoxin).

Corglyconum is short acting for acute cardiac insufficiency and administered intravenously.

Cordiamin – analeptic; Adrenaline is commonly used in shocks and coma;

Explanation

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

NH₃ + α-ketoglutarate → Glutamate

α-ketoglutarate is used up which leads to:

·        ↑glutamate → ↑GABA (inhibitory neurotransmitter)

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

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

NH₃ + Glutamate → Glutamine

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

                                    NH₃ + H⁺ → NH₄⁺

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

Explanation

In many tests in which antibodies are detected in the patient’s serum, an acute and convalescent serum sample is obtained and at least a fourfold increase in titer (1:100 – 1:400) between the acute and convalescent samples must be found for a diagnosis to be made. The reason these criteria are used is that the presence of antibodies in a single sample could be from a prior infection, so a significant (fourfold or greater) increase in titer is used to indicate that this is a current infection. IgM antibody can also be used as an indicator of current infection.

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

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

Defects in male genitalia:

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

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

Explanation

          The 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

Explanation

The question describes an adaptative mechanism causing increased aldosterone secretion which leads to decreased sodium ion excretion in sweat, due to the fact that increased aldosterone leads to increased reabsorption of sodium.

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

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.

Fibrinous colitis stage produces a dirty grayish pseudomembrane (film). Catarrhal colitis stage produces edema (inflamed) and hyperemic mucosa.

Explanation

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

Explanation

       Thalassemia or target cell anemia or Cooley’s anemia is an hemoglobinopathy (abnormal hemoglobin in RBCs). Defect in α-globin chain results in α thalassemia; and point mutations in β-globin chain results in β thalassemia. It is characterized microscopically by anisocytosis, poikilocytosis, target cells and is characterized by increased hemolysis, enlargement of spleen and liver, progressive anemia with erythroblastemia (reticulocyte). It’s a microcytic, hypochromic anemia.

Sickle cell anemia is also a hemoglobinopathy (abnormal hemoglobin in RBCs). It results as a result of a point mutation causing a single amino acid replacement in β chain (substitution of glutamic acid with valine) to produce hemoglobin S (HbS). The condition is characterized by the presence of sickle-like erythrocytes revealed during crisis, they cause stasis, hemorrhages and infarctions.

Explanation

Abstinence syndrome is renewal or deterioration of the disease after cessation of the drug administration. It is the withdrawal symptoms that occur after abstinence/stoppage of a drug, especially after taking the drug for some relatively long time (e.g. a narcotic).

       Hypertensive crisis is a deterioration of the initial hypertension.

Explanation

IL-1 is produced by macrophages, endothelium, keratinocytes, microglia, B-lymphocytes, fibroblasts, dendritic cells. Pro-inflammatory effects depend on IL-1, also induction of adhesive molecules, endopyrogenic activity, reason of prodromal syndrome, trigger of the reaction of an acute phase of inflammation and induction of synthesis of acute phase reactants, the main mediator of the immune reaction to alien substances, stimulator of stress.

Explanation

  ·        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. Trifacial nerve (Trigeminal nerve CNV), a cranial nerve. Parasympathetic system is craniosacral i.e. it has cranial and sacral segments.

·        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.

Explanation

Nephrotic syndrome is characterized by massive proteinuria (>3.5g/day) with hyperlipidemia, hypoalbuminemia (hypo- and dysproteinemia), edema etc. It may be primary (direct podocyte damage) or secondary (podocyte damage from systemic process e.g. diabetes). For example – focal segmental glomerulosclerosis, minimal change disease, membranous nephropathy, amyloidosis, diabetic glomerulonephropathy.

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

         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.

      ↓vasopressin → ↓H₂O reabsorption → polyuria

Explanation

Calcium (above 98%) and phosphorus (about 86%) are mainly fixed in bones and teeth, from where they can be mobilized in case of immediate organism needs. The role of calcium in the organism consists in the participation in bone and teeth construction, transmission of nervous stimulation, blood clotting, regulation of membranes permeability, muscle contraction etc. Therefore, a deficiency of Ca²⁺ → ↓density of teeth and ↑fragility.

Explanation

Lung emphysema is characterized by increased airiness of the lungs due to overdistended or destroyed alveoli. The patient mainly complains of dyspnoea, which at the onset of the disease may only develop during exercise but later it occurs at rest. Dyspnea increases in cold seasons, in chills and exacerbations of bronchitis; it is especially pronounced during attacks of cough. Dyspnea is usually of an expiratory type: a healthy person expire air with ease whereas the patient with emphysema presses it out from the chest with an effort.

Explanation

Fibrinous inflammation or pseudomembranous inflammation is an inflammatory response of mucous surface (oral, respiratory, bowel) to toxins of diphtheria or irritant gases. There are 2 types of fibrinous inflammation: croupous and diphtheric fibrinous inflammation. Local changes of diphtheric inflammation in the pharynx is characterized by small gray or white patches of exudates which appear over the pharyngeal mucosa, usually over the tonsils. The epithelial surface becomes necrotic and easily adherent to the underlying membrane. Attempts to remove this necrotic membrane may expose raw bleeding points. The soft tissues of the neck are edematous.

Explanation

Morphine is the major analgesic drug contained in crude opium. Opoids exert their major effects by interacting with opoid receptors in the CNS and in other anatomic structures, such as the GIT and the urinary bladder. Severe respiratory depression can occur and result in death from acute opoid poisoning. A serious effect of the drug is stoppage of respiratory exchange in patients with emphysema or Cor pulmonale. In this case, there is dysregulation of the respiratory center in the CNS.

Explanation

Explanation

           Reference interval (adults): 60 – 80g/L

40g/L is low i.e. a low oncotic pressure.

Glomerular filtration rate (GFR) is inversely proportional to oncotic pressure/colloid osmotic pressure, which is exerted by plasma proteins in the glomerular capillary blood. When oncotic pressure is low, GFR increases. Reabsorption is decreased, because the low oncotic pressure is not sufficient to reabsorb water and other substances (cannot create enough pressure to reabsorb water and other substances).

Explanation

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

Explanation

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

Polycyclic aromatic hydrocarbons (PAH) or simply polycyclic hydrocarbons may be released during the combustion of fossil fuels, particularly when coal and gas are burnt at high temperatures (e.g. in steel foundries) and are present in tar and soot (Pott identified soot as the cause of scrotal cancers in chimney sweeps in 1775). Polycyclic hydrocarbons are among the most potent carcinogens and industrial exposures have been implicated  in the development of lung, respiratory tract and bladder cancer. NB: a stoker is a person who tends a furnace specifically of a steam boiler, on a ship, locomotive etc.

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

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

Explanation

Explanation

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

Proserin (neostigmine) is an indirect acting cholinergic agonist (anticholinesterase). It preserves endogenous acetylcholine which can stimulate a greater number of acetylcholine receptors at the muscle endplate. Thereby increasing intestinal peristalsis and tone of urinary bladder.

Dichlothiazide – thiazide diuretic; Reserpine – sympatholytic; Mannitol – Osmotic diuretic; Propanolol – β-adrenoblocker.

Explanation

Demodex folliculorum and Demodex brevis: they are species of face mite. When large numbers of D. folliculorum are found in humans, the infestation is known as Demodicosis. D. folliculorum is semi-transparent elongated organism consisting of a head, neck, body and tail. As an adult, it can measure 0.1-0.4mm in length and possess 4 pairs of short legs near its head and neck region. In the course of time, because of chronic progradient course, pathologic process results in formation of inflammatory nodes, infiltrates and persistent vascular dilatation. Hyperemia of facial skin and eruptions are also seen.

Explanation

Considering the options, the most specific for diagnosis is     study antigenic     because

Reactions of antigens and antibodies are highly specific. An antigen will react only with antibodies elicited by itself or by a closely related antigen. Because of the great specificity, reactions between antigens and antibodies are suitable for identifying one (either the antibody or antigen) by using the other. To identify isolated causative agent, it is necessary to detect antigen in the patient’s specimen. Use known antibody to detect presence of antigens of the organisms.

Explanation

Skin cancer (epithelial tumors) are 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

         Nodal or atrioventricular (AV) extrasystole is caused by stimulus arising from AV node. The excitation of the atria differs from normal, the impulse is transmitted retrogradely from bottom to top. The following signs are characteristic of the ECG in nodal extrasystole:

·        Premature appearance of the cardiac complex.

·        Changes in the P wave which becomes negative to show the retrograde atrial excitation (in some cases the P wave is absent on the ECG).

·        If the atria and ventricles are excited synchronously, the P wave superimposes (overlaps) the QRS complex.

Explanation

Immunofluorescence (fluorescent antibody): fluorescent dyes e.g. fluorescein and rhodamine, can be covalently attached to antibody molecules and made visible by UV light in the fluorescence microscope. The immunofluorescence reaction is DIRECT when known labeled antibody interacts directly with unknown antigen and INDIRECT when a two-stage process is used e.g. known antigen is attached to a slide, the patient’s serum (unlabelled) is added and the preparation is washed; if the patient’s serum contains antibody against the antigen, it will remain fixed to it on the slide and can be detected on addition of a fluorescent dye-labelled antibody to human IgG and examination by UV microscopy. The indirect test is often more sensitive than direct immunofluorescence, because more labeled antibody adheres per antigenic site. Immunofluorescence staining of cells obtained from the patient or of cells infected in culture can provide a rapid and specific diagnosis.

Explanation

For the parents to survive and have a sick anemic child, they must be heterozygous i.e. they only carry a recessive anemic allele.

 A – normal gene (dominant); a – anemic gene (recessive)

            Aa       X          Aa

AA       Aa       Aa       aa

aa – only this child will be anemic

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

Explanation

Hepatitis is inflammation of the liver. The liver is the main site of protein synthesis i.e. synthesis of albumin, globulin, fibrinogen etc., which are necessary to maintain plasma oncotic pressure. In a situation of hepatic failure, there is decrease of protein synthesis which results in decreased oncotic pressure and then, edema. Therefore, an impairment of protein synthetic function of liver leads to the formation of edema.

Explanation

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

Explanation

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

Explanation

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

·        Tryptophan → Niacin → NAD⁺/NADP⁺

         Tryptophan → Serotonin →Melatonin

·        Histidine → Histamine

·        Glutamine → GABA

Explanation

Explanation

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

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

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

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

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

Explanation

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

Bee sting can initiate an inflammatory process, which leads to the release of biogenic amines and other important inflammatory mediators. Histamine is one of the most important inflammatory mediators. Histamine is synthesized and secreted from tissue basophils, thrombocytes, endothelium and smooth muscle cells. Activation of H₁-receptors leads to bronchospasm, activation of chemotaxis and lymphocytotoxicity, generation of lipid mediators, increase of vessels permeability and dilatation of resistance vessels (arterioles). Increase in vessels permeability leads to the formation or accumulation of exudates i.e. the escape of fluid, proteins and blood cells from the vascular system into the interstitial tissue or body cavities (i.e. edema). Edema denotes an excess of fluid in the interstitial tissue or serous cavities. It can be either an exudate or a transudate. An exudate is an inflammatory extravascular fluid that has a high protein content, specific gravity and many cells.

Explanation

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

·        Tryptophan → Niacin → NAD⁺/NADP⁺

          Tryptophan → Serotonin →Melatonin

·        Histidine → Histamine

·        Glutamine → GABA

Explanation

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

Explanation

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

Explanation

Group A streptococci produce 5 important toxins and hemolysins as follows:

·        Erythrogenic toxin: causes the rash of scarlet fever.

·        Streptolysin O is a hemolysin that is inactivated by oxidation (oxygen-labile). It is antigenic, and antibody to it (ASO – antistreptolysin O) develops after group A streptococcal infections. The titer of ASO antibody can be important in the diagnosis of rheumatic fever.

·        Streptolysin S is a hemolysin that is not inactivated by oxygen (oxygen-stable). It is not antigenic.

·        Pyogenic exotoxin A is the toxin responsible for most cases of streptococcal toxic shock syndrome.

·        Exotoxin B is a protease that rapidly destroys tissue and is produced in large amounts by the strains of S. pyogenes, the so-called “flesh eating” streptococci that cause necrotizing fascitis.

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

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

Explanation

Bordetella pertussis causes whooping cough (pertussis). B. pertussis is a gram negative bacillus (rod). It is a pathogen only for humans, transmitted by airborne droplets produced during the severe coughing episodes. In lab diagnosis, the organism can be isolated from nasopharyngeal swabs taken during the paroxysmal stage. Bordet-Gengou medium used for this purpose contains a high percentage of blood (20-30%) to inactivate inhibitors in the agar.

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

The normal and pathologic development and growth can be divided into the following stages:

·        Progenesis: characterized by gametogenesis i.e. formation and maturation of gametes. This stage occurs before the fertilization of the ovum. Pathology of gametogenesis is called gametopathy.

·        Development after fertilization is called kymatogenesis. This intrauterine phase can be divided into:

-         Blastogenesis: from day 1 – 15 of gestation. Pathology of blastogenesis is called blastopathy.

-         Embryogenesis: from day 16 to the end of the 3^rd month (75^th day). Pathology of embryogenesis is called embryopathy.

-         Fetogenesis: from the 4^th month of gestation to delivery (from 76^th -280^th day). Pathology of fetogenesis is called fetopathy.

     Gametopathy is an injury of formation and maturation of the gametes during ovo- and spermatogenesis until fertilization. The most frequent is trisomy 21 (Down’s syndrome); trisomy 13 (Patau’s syndrome), trisomy 18 (Edward’s syndrome), Klinefelter’s syndrome (XXY), Turner’s syndrome (XO).

Explanation

Normal hematocrit is approximately 45%. After a long physical activity, his circulating blood volume is reduced as a result of profuse sweating which can also produce relative hyperproteinemia (in the absence of any pathology). This decrease in blood liquid compartment has caused a relative increase in blood cells, increasing the hematocrit to 50% i.e. decrease in blood liquid compartment → ↑blood concentration → ↑hematocrit. Hematocrit is the percentage of cells present in plasma. In this case, no increase in plasma cell synthesis but a reduction in blood liquid compartment (through sweat) leads to an increase in the plasma cell percentage relative to the liquid component.

Explanation

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

                                                                                 Women: 2 – 15mm/h

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

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

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

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

Explanation

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

Histamine is one of the most important inflammatory mediators. Histamine is synthesized and secreted from tissue basophils, thrombocytes, endothelium and smooth muscle cells. Activation of H₁-receptors leads to bronchospasm, activation of chemotaxis and lymphocytotoxicity, generation of lipid mediators, increase of vessels permeability and dilatation of resistance vessels (arterioles). Increase in vessels permeability leads to the formation or accumulation of exudates i.e. the escape of fluid, proteins and blood cells from the vascular system into the interstitial tissue or body cavities (i.e. edema). Edema denotes an excess of fluid in the interstitial tissue or serous cavities. It can be either an exudate or a transudate. An exudate is an inflammatory extravascular fluid that has a high protein content, specific gravity and many cells.

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

Vagus nerve branches that innervate the heart produce parasympathetic effects on heart’s function e.g. ↓heart rate, force of contraction etc. This is as a result of hyperpolarization of the pacemaker cells. Hyperpolarization is as a result of K⁺ efflux (K⁺ yield) making it take a longer time for the cell to reach the threshold potential. This delay in reaching the threshold produces the delay or decrease in heart rate.

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

Explanation

The paired palatine tonsil (tonsilla palatina) lies in the tonsillar sinus, (fossa tonsillaris) between the palatoglossal and palatopharyngeal arches (palatine arches). Palatoglossal arch (the anterior pillar of fauces), is paired running down from the soft palate to the margins of the tongue. Palatopharyngeal arch, also paired runs down from the soft palate to the lateral wall of the pharynx, ending behind the latter. Tonsillar sinus is a depression between the palatine arches, which contains the palatine tonsil.

Explanation

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

Explanation

The inferior mesenteric artery arises from the anterior aspect of the abdominal aorta. The artery gives the branches as follows: left colic artery (arteria colica sinistra); sigmoid arteries (supplies sigmoid colon) and superior rectal artery (supplies the rectum). Left colic artery (sinister colic) ascends leftwards to supply the descending colon. On reaching the intestine, the artery gives the ascending and descending branches that anastomose with the middle colic artery and sigmoid artery.

Explanation

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

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

Explanation

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

Explanation

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

Cardiac insufficiency: Cardiac glycoside is the most appropriate in this case. Cardiac glycosides are glycosidic drugs of plant origin having cardiac inotropic property, increase myocardial contractility and output.

Digitoxin is long-acting but basically administered orally and used mainly for chronic heart failure (also digoxin).

Explanation

The pituitary gland (hypophysis) occupies the hypophysial fossa in the sella turcica of sphenoid bone. Therefore, a tumor of this gland can cause enlargement of the sellar cavity and destruction of different parts of sella turcica.

Explanation

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.

Explanation

Necrosis can initiate or induce an inflammatory reaction.

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

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

Explanation

Cellular immunity or T-cell immunity involves majorly the T cells.

B-lymphocytes differentiates into plasma cells which then produce antibodies or immunoglobulins (IgG, IgE …). They participate more in humoral immunity.

Immunodeficiency disorders is a good soil for opportunistic pathogenic infections (e.g. skin mycosis). Therefore, a disorder of cellular immunity indicates a reduction in T-lymphocyte count.

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

Explanation

Medulloblastoma is a tumor made by immature cells, medulloblasts; therefore it is highly malignant. It is localized in the vermis of cerebellum. Macroscopically, it is pinkish-gray. Microscopically, medulloblastoma consists of homogenous small cells with dark round or oval nucleus and poorly seen rim of cytoplasm. The cells are located close to each other. Rosette is typical. Mitoses are numerous. Vessels are not numerous. Metastasis spread through the liquor routs.

Explanation

Central chemoreceptors are responsible for 70 – 80% of increased ventilation through chemical regulatory mechanism. Main stimulant for central chemoreceptors is the increased hydrogen ion concentration. However, if H⁺ concentration increases in blood, it cannot cross the blood-brain barrier and blood-cerebrospinal fluid barrier. On the other hand, if CO₂ increases in the blood, it can easily cross the blood-brain barrier and blood-CSF barrier and enter the interstitial fluid of brain or the CSF. There, the CO₂ combines with water to form carbonic acid. Since carbonic acid (H₂CO₃) is unstable, it immediately dissociates into H⁺ and bicarbonate ion.

Then H⁺ stimulates the central chemoreceptors. From chemoreceptors, the excitatory impulses are sent to dorsal respiratory group of neurons, resulting in increased ventilation (increased rate and force of breathing). Lack of O₂ does not have significant effect on the central chemoreceptors, except that it generally depresses the overall function of brain.

Explanation

What forms the walls of the ingunal canal:

·        Anteriorly: the aponeuroses of the external and internal oblique muscles.

·        Posteriorly: the transversalis fascia.

·        Superiorly: the arching fibers of the internal oblique and transverses abdominis muscles.

·        Inferiorly: the inguinal ligament.

Contents:

·        Men: Spermatic cord (funiculus spermaticus) and the ilioinguinal nerve

·        Women: round ligament of the uterus (ligamentum teres uteri) and the ilioinguinal nerve.

Explanation

P-Q or P-R interval is the interval between the onset of ‘P’ wave and onset of ‘Q’ wave. This interval signifies the atrial depolarization and conduction of impulses through the AV node. Short isoelectric (zero voltage) period after the end of ‘P’ wave represents the time taken for the passage of depolarization within the AV node. Normal duration of P-Q interval is 0.18s and varies between 0.12 and 0.20s. If it is more than 0.20s, it signifies a delay in the conduction of impulse, usually, the delay occurs in the AV node. It is prolonged in bradycardia and Atrioventricular (AV) heart block i.e. delay in conduction of impulse through the AV node.

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.

Explanation

Cytotoxic T cells destroy cancer cells, transplanted cells, such as those of transplanted heart or kidney or any other cells, which are foreign bodies. They destroy even the body’s own tissues which are affected by the foreign bodies, particularly the viruses.

     Helper T cells (CD4 cells) activate all the other T cells and B cells.

     B cells – plasma cells – antibodies: major defense against bacterial infections.

     Natural killer (NK) cells: destroy viruses, malignant cells and prevents development of cancerous tumors.

    Interleukin are cytokines produced by leukocytes to act on other leukocytes e.g. IL-1, IL-2, IL-3, IL-12 etc.

Explanation

There are four medically important clostridium species: Clostriidum tetani (causes tetanus), Clostridium botulinum (causes botulism), Clostridium perfringes (causes either gas gangrene or food poisoning) and Clostridium difficile. All Clostridia are anaerobic, spore-forming, gram positive rods (violet-blue gram’s stain).

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

The introduction of an allograft (that is, the graft of an organ or tissue from one individual to another who is not genetically identical) can elicit a damaging immune response, causing rejection of the transplanted tissue. Drugs (immunosuppressors) are now available that more selectively inhibit rejection of transplanted tissues while preventing the patient from becoming immunologically compromised. The principal approach to immunosuppressive therapy is to alter lymphocyte function using drugs or antibodies against immune proteins. Immunosuppressive therapy is also used in the treatment of autoimmune diseases e.g. adrenocorticoids (prednisolone).

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

Cholera is an acute gastrointestinal infectious quarantinic disease and is characterized by diarrhea and exicosis. It has 3 clinical-morphological stages: choleric enteritis, choleric gastroenteritis and choleric exicosis (algid). Choleric gastroenteritis is characterized by the hard diarrhea, vomit and increase of dehydration. The loss of sodium and water causes severe diarrhea called “rice-water stool.” Fluid loss may exceed 1 liter per hour. Death occurs in algid period and is caused by dehydration, coma, uremia and intoxication.

Explanation

Multiple myeloma is a monoclonal plasma cell (“fried egg” appearance) cancer that arises in the marrow and produces large amounts of IgG (55%) or IgA (25%). It is the most common primary tumor arising within bone in people >40 – 50 years old. It is characterized by hypercalcemia; renal involvement; anemia; bone lytic lesions (osteoporosis); back pain. MM: monoclonal M protein spike.     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.

Myeloma/Plasmocytoma/Multiple Myeloma

Explanation

Ulcer is a local defect on the surface of an organ produced by inflammation. Morphogenesis and morphology of peptic ulcer disease includes: erosions, acute ulcer and chronic ulcer.

    Acute ulcer is characterized by loss of tissue penetrating into the submucosa. It is a single or multiple lesions through the stomach and duodenum. It is circular and small, less than 1cm in diameter. Inflammatory reaction is absent initially but develops secondarily. Massive hemorrhage may be fatal. This type of ulcer usually heals without a visible scar.

    Chronic ulcers are characterized by fibrinoid necrosis and granulation tissue with plasma cell and lymphocytic infiltration, also scarring. But there is no granulation tissue or fibrous tissue mentioned in the question.

Explanation

Adult polycystic disease is inherited as an autosomal dominant trait, generally becoming clinically manifest in adult life. Cysts develop and progressively enlarge over a number of years, but remain asymptomatic until the number and size of the cysts is so great that the patient becomes aware of abdominal masses. At about the same time, the replacement and compression of functioning renal parenchyma by the cysts leads to slowly progressive impairment of renal function and patients develop chronic renal failure (uremia) and hypertension.

Bilateral – both kidneys

Cyst – a cavity that may be filled with gas, liquid or solid

Explanation

Primary motor area extends throughout the precentral gyrus and the adjoining lip of central sulcus. Areas 4 and 4S are present here. Muscles of various parts of the body are represented in area 4 in an inverted way from medial to lateral surface. Lower parts of the body are represented in the lateral (upper) surface and upper parts of the body are represented in the lateral (lower) surface. Order of representation from medial (superior, upper) to lateral (inferior, lower) surface: toes, ankle, knee, hip, trunk, shoulder, arm, elbow, wrist, hand, fingers and face. Area 4 is concerned with contraction of discrete muscles.

Explanation

Hemadsorption i.e. attachment of erythrocytes to the surface of virus-infected cells. This technique is limited to viruses with a hemagglutinin protein on their envelope such as mumps, parainfluenza and influenza viruses.

Explanation

Atelectasis refers to partial or complete collapse of the lungs. Its major cause is deficiency or inactivation of surfactant. It causes collapse of lungs due to increased surface tension, which leads to respiratory distress syndrome. Other causes include obstruction of a bronchus or a bronchiole; presence of air (pneumothorax), fluid (hydrothorax), blood (hemothorax) or pus (pyothorax) in the pleural space.

Explanation

Intoxication with drugs leads to:

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

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

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

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

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

Mental and physical development lag; fetal alcohol syndrome are fetal malformations.

Explanation

Bile capillaries/bile canaliculus is a  small canal formed by apposed grooves on the surface of adjacent hepatocytes. Bile canaliculi form a complete loop around four sides of the idealized six-sided hepatocytes. The hepatocytes separate blood and bile, so they do not mix. Bile flow is centrifugal i.e. from the region of the central vein toward the portal canal (a direction opposite to the blood flow).

Explanation

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

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

B₁₂ –folic acid deficiency: megaloblastic macrocytic anemia

Sickle cell anemia: sickled shaped or modified shaped erythrocytes

Hemolytic anemia: in chronic conditions, its manifestations are very similar to iron deficiency anemia.

Thalassemia: target cell, anisocytosis, poikilocytosis.

Explanation

Potassium permanganate is a non-organic antiseptic and disinfectant. Its an oxidizing agent liberating oxygen, which oxidizes bacterial protoplasm. KMnO₄ → MnO₂ + O₂.

MnO – astringent action; O₂- oxidizing proteins in microbes, deodorizing action, antidote action.

Potassium permanganate is used in disinfections of impaired skin and mucous areas, irrigation of pus wounds.

·        Irrigation of purulent wounds (0.01 – 0.5% solution)

·        Gargling and mouthwash in diseases of throat and oral cavity (0.01 – 0.1% solution)

·        Syringing in gynecology and urology (0.01 – 0.1% solution)

·        Processing of burns (2 – 5% solution)

·        Lavage of stomach in acute poisoning with morphine, alcohol (0.1% solution)

Furacillin: organic antiseptic and disinfectant → furan derivative

Chlorhexidine bigluconate: nonorganic antiseptic and disinfectant → halogen → chlorine containing

Alcoholic iodine solution: nonorganic antiseptic and disinfectant → halogen → iodine containing

Sodium hydrocarbonate: drug for transfusion therapy → drug for correction of acidosis.

Explanation

Urolithiasis or formation of urinary calculi at any level of the urinary tract is a common condition. There are 4 main types of urinary calculi, namely:

·        Calcium stones: are the most common comprising 75% of all urinary calculi. They may be pure stones of calcium oxalate (50%) or calcium phosphate (5%) or mixture of calcium oxalate.

·        Mixed (struvite) stones: about 15% of urinary calculi are made of magnesium-ammonium-calcium phosphate often called struvite. “Staghorn stone”

·        Uric acid stones: can be seen in gout, Lesch-Nyhan syndrome (hyperuricemia).

·        Cystine stones: seen in cases like cystinuria.

NB: hyperparathyroidism → ↑Ca²⁺ concentration in blood.

Explanation

Effect of repeated doses include: accumulation, tolerance (habituation), tachyphylaxis and drug dependence.

            Accumulation is enhancing of the effects in repeated doses that leads to the appearance of toxic effects. 2 types are distinguished:

·        Material accumulation: is accumulation of drug in the manner of bindings with proteins, phospholipids etc.

·        Functional accumulation is accumulation of the drug effect, in spite of its elimination.

The cardiac glycosides are often called digitalis or digitalis glycosides, because most of the drugs come from the digitalis (foxglove) plant. Non-polar glycosides (digitoxin) are fully absorbed and firmly connected with proteins – plasma protein binding 95%. These drugs are accumulated.

Explanation

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

Explanation

Explanation

      Isoosmolar hypohydration (isoosmotic loss): proportional volume decrease of fluids and electrolytes e.g. in blood loss, burns, diuretic therapy, especially diarrhea in cholera.

     Hypoosmolar hypohydration (salt deficit) develops due to diarrhea, vomiting, sweating, adrenal insufficiency, hypokalemia, CNS lesions, salt-losing nephritis.

          Hyperosmolar hypohydration (water defcit) develops due to the loss of the fluid which lacks electrolytes e.g. in diabetes insipidus, hyperventilation.

         Hypoosmolar hyperhydration (water excess) develops in acute renal failure (in the stage of anuria), Parhon’s syndrome (syndrome of inappropriate ADH secretion –SIADH).

         Hyperosmolar hyperhydration (salt excess) develops rarely e.g. in drinking salt (sea) water, infusion of hypertonic saline, adrenal hyperactivity or steroid therapy.

Explanation

Foreign bodies inspired into the trachea are most likely to be found in the right main bronchus because it is wide and believed to be a continuation of the trachea. The superior lobe of the right lung consists of 3 segments: apical segment, posterior segment and anterior segment. A foreign body closing the right superior lobar bronchus will prevent air supply to these 3 segments listed above.

Explanation

Labia majora/labia majus (large lips of pudendum) are paired thickened skin folds covered with hair. The labia enclose the pudendal cleft and protect deeper pudendal organs. The greater vestibular glands (bartholin’s glands) are paired rounded organs in size (about 1cm wide). They reside under the perineal membrane posterior to the bulb of vestibule in the base of the labia majus laterally to the vaginal orifice. The bartholin’s gland is similar to the bulbo-urethral glands in males. They produce secretions, which moistens the vaginal inlet.

Explanation

Specific names are given to epithelium in certain locations:

·        Endothelium is the epithelial lining of the vascular system (e.g. artery)

·        Mesothelium is the epithelium that lines the walls and covers the contents of the closed cavities of the body i.e. the abdominal, pericardial and pleural cavities.

Endothelium and mesothelium are the simple squamous (flat) epithelial lining the vascular system and body cavities respectively.

Explanation

     The P450 system is impotant for the metabolism of many endogenous compounds (such as steroids, lipids etc) and for the biotransformation of exogenous substances (xenobiotics). Cytochrome P450, designated as CYP, is a superfamily of heme-containing isozymes that are located in most cells but are primarily found in the liver and GIT. Phase I reactions utilizing the P450 system (also called microsomal mixed function oxidases). The oxidation proceeds by the xenobiotic binding to the oxidized form of cytochrome P450 and then O₂ is introduced through a reductive step, coupled to NADPH: cytochrome P450 oxidoreductase.

Explanation

Recurrent laryngeal nerve arises from the cervical part of the vagus nerve within the upper portion of the thoracic cavity yet its branches terminate in the cervical region. The left nerve loops around the aortic arch, the right nerve loops around the subclavian artery. Both nerves return to the cervical region where they reside between the trachea and the esophagus. The nerve comprises all types of fibers and supplies the trachea, esophagus, all laryngeal muscles (except for the cricothyroid) and the laryngeal mucosa below the rima glottidis. Injury to the recurrent laryngeal nerve results in aphonia (inability to produce voice) because of laryngeal muscles paralysis.

Explanation

     Hyperthermia (i.e. marked warming of core temperature) is not mediated by pyrogens and there is no resetting of the hypothalamic set point. It may be accidental or therapeutic.

Explanation

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

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

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

Explanation

Irritant receptors are stimulated by irritant chemical agents. These receptors send afferent impulses to respiratory centers via vagal nerve fibers. Stimulation of irritant receptors produces reflex hyperventilation along with bronchospasm. Hyperventilation along with bronchospasm prevents further entry of harmful agents into the alveoli.

Explanation

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

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

Explanation

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

True dermal ridges are present in thick skin in addition to dermal papillae. Dermal ridges tend to have a parallel arrangement, with the dermal papillae located between them. These ridges form a distinctive pattern that is genetically unique to each individual and is reflected in the appearance of epidermal grooves and ridges on the surface of the skin. These patterns are the basis of the science of dermatoglyphics, or fingerprint and footprint identification. The dermal ridges and papillae are most prominent in the thick skin of the palmar and plantar surfaces.

Explanation

Acyclovir is an antiviral drug for herpes and cytomegalovirus infections. The drug is indicated for primary and recurrent mucocutaneous herpes simplex infections in immunocompromised patients. It is also useful in herpes genitalis infections.

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

During the onset of depolarization and voltage gated sodium channels open and there is slow influx of Na⁺. When depolarization reaches 7 – 10mV, the voltage gated Na⁺ channels start opening at a faster rate. It is called Na⁺ channel activation. When the firing level is reached, the influx of Na⁺ is very great and it leads to overshoot. The gradual influx of Na⁺ lowers the threshold of stimulation force.

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

         The anterior jugular vein arises from small superficial veins of the sublingual area. The veins descend to the manubrium of sternum and merge to form the jugular venous arch. The lateral ends of the arch open into the external jugular vein before it joins the venous angle.

NB: veins are located superficially to arteries.

Explanation

Explanation

Opoids (narcotic analgetic) are natural or synthetic compounds that produce morphine-like effects. All drugs in this category act by binding to specific opoid receptors in the CNS to produce effects that mimic the action of endogenous peptide neurotransmitters (e.g. endorphins, enkephalins and dynorphins). Although the opoids have a broad range of effects, their primary use is to relieve intense pain, whether that pain is from surgery or a result of injury or disease such as cancer.

Explanation

Major proteolytic enzymes of pancreatic juice are trypsin and chymotrypsin. Trypsin is the most powerful proteolytic enzyme. It is an endopeptidase and breaks the interior bonds of the protein molecules and converts proteins into proteoses and polypeptides.

Explanation

Olfactory receptors (1^st order neuron) → Mitral cells (2^nd order neuron) → Olfactory tract → Olfactory trigone, anterior perforated substance, septum pellucidum (3^rd order neuron) → Uncus of parahippocampal gyrus.

The Olfactroy analyzer is one of the oldest ones so it features several fibers that take the shortest route to the Olfactory cortex i.e. do not relay within the thalamus.

Gustatory: through its 2^nd order neuron from medial lemniscus → thalamus.

Visual: through its subcortical visual centers → pulvinar of thalamus

Tactile (skin analyzer); Auditory: through lateral lemniscus of inferior colliculi of tectal plate and medial geniculate bodies of metathalamus.

Explanation

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

Explanation

Pathological chest:

·        Keeled or pigeon or rachitic chest: characterized by a markedly greater anteroposterior diameter (compared with the transverse diameter) due to the prominence of the sternum (which resembles the keel of a boat).

·        Funnel chest can occur in normosthenic, hypersthenic or asthenic subjects; it has a funnel-sheped depression in the lower part of the sternum.

·        Emphysematous or barrel-like chest resembles a hypersthenic chest in its shape, but differs from it by a barrel-like conjuration, prominence of the chest wall especially in the posterolateral regions, the intercostals spaces are enlarged.

Explanation

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

Explanation

The midbrain comprises the tectal (quadrigeminal, quadritubercular) plate and the cerebral peduncles. Between them is the cerebral aqueduct. Each cerebral peduncle features the ventral portion called the base of peduncle and the dorsal portion called the tegmentum of midbrain. The red nucleus is localized in the tegmentum of midbrain. The red nucleus is one of the biggest nuclei of midbrain.