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Question 1
Incorrect
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Which of the following diseases causes abrupt vertigo, nausea, vomiting, tinnitus, and nystagmus?
Your Answer: Cerebral oedema
Correct Answer: Vestibular neuronitis
Explanation:Vestibular neuronitis or labyrinthitis causes a self-limited episode of vertigo, presumably due to inflammation of the vestibular division of cranial nerve VIII. Its causes are unknown, It may be due to a virus, but it can be related to a bacterial infection, head injury, stress, allergy, or as a reaction to medication. Symptoms can last up to 7-10 days.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 2
Correct
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After a car accident, a 30-year-old woman is alert and only has minor, superficial injuries. 2 hours later, she becomes unconscious and a CT scan reveals a convex, lens-shaped haemorrhage over the right parietal region. The most likely diagnosis is:
Your Answer: Epidural haematoma
Explanation:Epidural haematomas are usually caused by arterial bleeding, classically due to damage to the middle meningeal artery by a temporal bone fracture. Symptoms develop within minutes to several hours after the injury and consist of increasing headache, decreased level of consciousness, hemiparesis and pupillary dilation with loss of light reactivity. Around 15–20% of epidural hematomas are fatal.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 3
Incorrect
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A patient is suspected to have a chromosomal abnormality. Which tumour and chromosomal association is correct?
Your Answer: Retinoblastoma – chromosome 11
Correct Answer: Neuroblastoma – chromosome 1
Explanation:Neuroblastoma is associated with a deletion on chromosome 1 and inactivation of a suppressor gene. Neurofibromas and osteogenic sarcoma are associated with an abnormality on chromosome 17. Retinoblastoma (Rb) is associated with an abnormality on chromosome 13. Wilms’ tumours of the kidney are associated with an abnormality on chromosome 11.
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This question is part of the following fields:
- Neoplasia
- Pathology
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Question 4
Correct
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The anatomical dead space in a patient with low oxygen saturation, is 125 ml, with a tidal volume of 500 ml and pa(CO2) of 40 mm Hg. The dead space was determined by Fowler's method. If we assume that the patient's lungs are healthy, what will his mixed expired CO2 tension [pE(CO2)] be?
Your Answer: 30 mmHg
Explanation:According to Bohr’s equation, VD/VT = (pA(CO2) − pE(CO2))/pA(CO2), where pE(CO2) is mixed expired CO2 and pA(CO2) is alveolar CO2pressure. Normally, the pa(CO2) is virtually identical to pA(CO2). Thus, VD/VT = (pa(CO2)) − pE(CO2)/pa(CO2). By Fowler’s method, VD/VT= 0.25. In the given problem, (pa(CO2) − pE(CO2)/pa(CO2) = (40 − pE(CO2)/40 = 0.25. Thus, pE(CO2) = 30 mmHg. If there is a great perfusion/ventilation inequality, pE(CO2) could be significantly lower than 30 mm Hg, and the patient’s physiological dead space would exceed the anatomical dead space.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 5
Correct
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A 42 year old women presents with end stage renal failure and is prepared to receive a kidney from her husband. HLA testing showed that they are not a 100% match and she is given immunosuppressant therapy for this. Three months later when her renal function tests were performed she showed signs of deteriorating renal function, with decreased renal output, proteinuria of +++ and RBCs in the urine. She was given antilymphocyte globulins and her condition reversed. What type of graft did this patient receive?
Your Answer: Allograft
Explanation:Allograft describes a graft between two of the same species. As the donor and the recipients are history-incompatible, rejection of the graft is common and is controlled by immunosuppressive drug therapy. Isograft and syngraft are synonymous and referred to a graft transferred between genetically identical individuals e.g. identical twins. In this case rejection is rare as they are history-compatible.
Autograft refers to transfer of one part of the body to another location.
Xenograft is transfer of tissue from another species e.g. pig to human in valve replacement surgeries and rejection is very high.
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This question is part of the following fields:
- Inflammation & Immunology; Renal
- Pathology
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Question 6
Correct
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A 45-year old farmer was referred to the surgical clinic with complaints of pain in his right hypochondrium. Investigations confirmed the diagnosis of hepatocellular carcinoma with malignant ascites. According to you, what is the most likely cause of HCC in this patient?
Your Answer: Aflatoxin
Explanation:Aflatoxins are naturally occurring toxins produced by the Aspergillus fungus (most often, A. flavus and A. parasiticus). These organisms are common and their native habitat is soil, decaying vegetation and grains. They can contaminate the grain before harvest or after storage, more likely in high-humidity (at least 7%) or high temperature environment of after stressful conditions like drought. Aflatoxins are mycotoxins and also carcinogenic. They get metabolized in the liver to an epoxide, aflatoxin M1. High exposure can lead to acute necrosis, cirrhosis or liver carcinoma. These substances can cause haemorrhage, acute liver damage, oedema, and alteration in digestion, absorption and/or metabolism of nutrients. Although humans are susceptible to these toxins like all other animals, they have a high tolerance level and hence, rarely develop acute aflatoxicosis. However, children are particularly susceptible to exposure leading to growth impairment and delayed development. Chronic exposure carries a high risk of hepatic cancer, due to intercalation of its metabolite aflatoxin M1 into the DNA and alkylation of the bases because of its epoxide moiety.
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This question is part of the following fields:
- Gastrointestinal; Hepatobiliary
- Pathology
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Question 7
Correct
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As per the Poiseuille-Hagen formula, doubling the diameter of a vessel will change the resistance of the vessel from 16 peripheral resistance units (PRU) to:
Your Answer: 1 PRU
Explanation:Poiseuille-Hagen formula for flow in along narrow tube states that F = (PA– PB) × (Π/8) × (1/η) × (r4/l) where F = flow, PA– PB = pressure difference between the two ends of the tube, η = viscosity, r = radius of tube and L = length of tube. Also, flow is given by pressure difference divided by resistance. Hence, R = 8ηL ÷ Πr4. Hence, the resistance of the vessel changes in inverse proportion to the fourth power of the diameter. So, if the diameter of the vessel is increased to twice the original, it will lead to decrease in resistance to one-sixteenth its initial value.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 8
Correct
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Ventricular filling follows a delay caused by?
Your Answer: AV node
Explanation:The AV node is a conducting tissue found between the atria and the ventricles of the heart. It conducts electrical signal from the atria to the ventricles and acts a delaying mechanism preventing the atria and the ventricles from contracting at the same time. This decremental conduction prevents premature ventricular contraction in cases such as atrial fibrillation. A delay in the AV node is the reason for the PR segment seen on the ECG. In certain types of supraventricular tachycardia, a person could have two AV nodes; this will cause a loop in electrical current and uncontrollably rapid heart beat. When this electricity catches up with itself, it will dissipate and return to a normal heart rate.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 9
Correct
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Which condition presents with a positive urine dipstick test for blood, but no blood cells on urine microscopy?
Your Answer: Myoglobinuria
Explanation:Myoglobinuria, or presence of myoglobulin in the urine is seen due to rhabdomyolysis (muscle destruction). Common causes of rhabdomyolysis include trauma, electrical injuries, burns, venom and drugs. Damaged muscle leads to release of myoglobin in the blood. Ideally, the released myoglobin gets filtered and excreted by the kidneys. However, excess myoglobin can occlude the renal filtration system leading to acute tubular necrosis and acute renal dysfunction.
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This question is part of the following fields:
- Pathology
- Renal
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Question 10
Incorrect
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What Is the mechanism behind rhesus incompatibility in a new born baby?
Your Answer: Type I hypersensitivity
Correct Answer: Type II hypersensitivity
Explanation:In type II hypersensitivity the antibodies that are produced by the immune response bind to the patients own cell surface antigens. These antigens can be intrinsic or extrinsic. Destruction occurs due to antibody dependent cell mediated antibodies. Antibodies bind to the cell and opsonise the cell, activating phagocytes to destroy that cell e.g. autoimmune haemolytic anaemia, Goodpasture syndrome, erythroblastosis fetalis, pernicious anaemia, Graves’ disease, Myasthenia gravis and haemolytic disease of the new-born.
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This question is part of the following fields:
- Inflammation & Immunology; Haematology
- Pathology
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Question 11
Correct
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A 66-year-old man complains of constant headaches. On physical examination, the only relevant sign is a dark brown mole located on left his arm which has grown in size over the years and is itchy and painful. A MRI of the brain revealed a solitary lesion at the grey-white junction in the right frontal lobe, without ring enhancement. This lesion is most likely to be:
Your Answer: Metastatic carcinoma
Explanation:The location of the mass at the grey–white junction is typical of a metastasis. The most frequent types of metastatic brain tumours originate in the lung, skin, kidney, breast and colon. These tumour cells reach the brain via the bloodstream. This patient is likely to have skin cancer, which caused the metastatic brain tumour.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 12
Correct
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A 45-year old lady underwent biopsy of a soft, fleshy mass involving her left breast. The biopsy showed lymphoid stroma with minimal fibrosis, surrounding sheets of large vesicular cells with frequent mitoses. Which condition is she most likely suffering from?
Your Answer: Medullary carcinoma of breast
Explanation:Medullary carcinoma is a malignant tumour of the breast with well-defined boundaries and accounts for 5% of all breast cancers. Other special features include a larger size of the neoplastic cells and presence of lymphoid cells at tumour edge. Differential diagnosis includes invasive ductal carcinoma. Prognosis is usually good.
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This question is part of the following fields:
- Pathology
- Women's Health
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Question 13
Correct
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An alcoholic patient was found to have hypomagnesaemia on blood tests. Which of the following clinical features will have prompted the doctor to check the serum magnesium level in this patient?
Your Answer: Seizures
Explanation:Hypomagnesaemia is a condition characterised by a low level of magnesium in the blood. The normal range for serum magnesium level is 0.75-1.05 mmol/l. In hypomagnesaemia serum levels of magnesium are less than 0.75 mmol/l. The cardiovascular and nervous systems are the most commonly affected. Neuromuscular manifestations include symptoms like tremor, tetany, weakness, apathy, delirium, a positive Chvostek and Trousseau sign, nystagmus and seizures. Cardiovascular manifestations include electrocardiographic abnormalities and arrhythmias e.g. ventricular fibrillation.
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This question is part of the following fields:
- Fluids & Electrolytes
- Pathology
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Question 14
Incorrect
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Mallory bodies are characteristic of which of the following conditions?
Your Answer: Primary biliary cirrhosis
Correct Answer: Alcoholic hepatitis
Explanation:Mallory bodies (or ‘alcoholic hyaline’) are inclusion bodies in the cytoplasm of liver cells, seen in patients of alcoholic hepatitis; and also in Wilson’s disease. These pathological bodies are made of intermediate keratin filament proteins that are ubiquinated or bound by proteins like heat chock protein. Being highly eosinophilic, they appear pink on haematoxylin and eosin staining.
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This question is part of the following fields:
- Gastrointestinal; Hepatobiliary
- Pathology
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Question 15
Correct
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What is the 5-year survival rate of carcinoma of the pancreas?
Your Answer: 30 per cent
Explanation:Pancreatic cancer typically has a poor prognosis, partly because the cancer usually initially remains symptomless, leading to locally advanced or metastatic disease at the time of diagnosis. Median survival from diagnosis is around 3–6 months. Even in those suitable for resectional surgery, 5-year survival rates are still only 30 per cent.
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This question is part of the following fields:
- Neoplasia
- Pathology
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Question 16
Correct
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13 year old girl developed sun burnt cheeks after spending the day playing on the beach. What is the underlying mechanism to her injury?
Your Answer: Free radical injury
Explanation:Free radicals are a by-product of chemical reactions with an unpaired electron in their outer most shell. They are capable of causing wide spread damage to cells. They can cause autolytic reactions thereby converting the reactants into free radicals. By absorbing sun light, the energy is used to hydrolyse water into hydroxyl (OH) and hydrogen (H) free radicals which can cause injury by lipid peroxidation of membranes, oxidative modification of proteins and damage to the DNA structure.
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This question is part of the following fields:
- Cell Injury & Wound Healing; Dermatology
- Pathology
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Question 17
Correct
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A 39-year-old man, after radiological evaluation and thoracentesis, was found to have chylothorax. What is the most probable cause of this diagnose?
Your Answer: Mediastinal malignant lymphoma
Explanation:Chylothorax is a potentially lethal condition characterized by fluid (chyle) accumulation in the pleural cavity, resulting from disruption of lymphatic drainage in the thoracic duct. Chyle is a fluid rich in triglycerides and chylomicrons and can originate from the thorax, the abdomen or both. Malignant tumours, especially lymphoma, are the most common causes of nontraumatic chylothorax. Bronchogenic carcinoma and trauma are the most common causes after lymphomas. Other rare causes of chylothorax are; granulomatous diseases, tuberculosis, congenital malformations, nephrotic syndrome, hypothyroidism, cirrhosis, decompensated heart failure and idiopathic chylothorax.
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This question is part of the following fields:
- Pathology
- Respiratory
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Question 18
Correct
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A 17-year-old boy, who had developed shortness of breath and a loss of appetite over the last month, was referred to a haematologist because he presented with easy bruising and petechiae. His prothrombin time, platelet count, partial thromboplastin and bleeding time were all normal. Which of the following would explain the presence of the petechiae and easy bruising tendency?
Your Answer: Scurvy
Explanation:Scurvy is a condition caused by a dietary deficiency of vitamin C, also known as ascorbic acid. Humans are unable to synthesize vitamin C, therefore the quantity of it that the body needs has to come from the diet. The presence of an adequate quantity of vitamin C is required for normal collagen synthesis. In scurvy bleeding tendency is due to capillary fragility and not coagulation defects, therefore blood tests are normal.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 19
Incorrect
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Which of the following accumulates within a cell due to the aging process?
Your Answer: Hemosiderin
Correct Answer: Lipofuscin
Explanation:Lipofuscin , also known as lipochrome, is a wear and tear pigment or an aging pigment. It represents free radical injury or lipid peroxidation. On microscopic examination is appears as a yellowish brown pigment around the nucleus (perinuclear pigment). It is often seen in cells which are undergoing regressive changes, commonly in the liver and heart of old patients or patients with cancer, cachexia or severe malnutrition.
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This question is part of the following fields:
- Cell Injury & Wound Healing
- Pathology
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Question 20
Correct
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Digital rectal examination of a 75-year old gentleman who presented to the surgical clinic with urinary retention revealed an enlarged, nodular prostate. PSA was found to be elevated, favouring the diagnosis of prostatic malignancy. Which of the given options is the most common malignant lesion affecting the prostate gland?
Your Answer: Adenocarcinoma
Explanation:Prostatic adenocarcinoma is the commonest solid malignancy and non-dermatological cancer in men above 50 years age. Increasing in incidence with age and the highest risk seen in the black population. About 75% of cases are seen in men over 65 years. Other tumours affecting the prostate include undifferentiated prostate cancer, squamous cell carcinoma, and ductal transitional carcinoma, but these occur less commonly. Sarcomas usually affect children. Hormones play a role in the aetiology of prostate adenocarcinoma unlike the other types. Intraepithelial neoplasia is considered a precursor of invasive malignancy.
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This question is part of the following fields:
- Pathology
- Urology
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Question 21
Incorrect
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A 31 -year-old female patient had a blood gas done on presentation to the emergency department. She was found to have a metabolic acidosis and decreased anion gap. The most likely cause of these findings in this patient would be?
Your Answer: Lactic acidosis
Correct Answer: Hypoalbuminemia
Explanation:A low anion gap might be caused by alterations in serum protein levels, primarily albumin (hypoalbuminemia), increased levels of calcium (hypercalcaemia) and magnesium (hypermagnesemia) or bromide and lithium intoxication. However, the commonest cause is hypoalbuminemia, thus if the albumin concentration falls, the anion gap will also be lower. The anion gap should be corrected upwards by 2.5 mmol/l for every 10g/l fall in the serum albumin.
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This question is part of the following fields:
- Fluids & Electrolytes
- Pathology
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Question 22
Correct
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Diffusion is the movement of molecules from a region of high concentration to a region of low concentration. Which of these changes will decrease the rate of diffusion of a substance?
Your Answer: An increase in the molecular weight of the substance
Explanation:Unless given IV, a drug must cross several semipermeable cell membranes before it reaches the systemic circulation. Drugs may cross cell membranes by diffusion, amongst other mechanisms. The rate of diffusion of a substance is proportional to the difference in the concentration of the diffusing substance between the two sides of the membrane, the temperature of the solution, the permeability of the membrane and, in the case of ions, the electrical potential difference between the two sides of the membrane.
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This question is part of the following fields:
- Fluids & Electrolytes
- Physiology
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Question 23
Correct
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A 25 year-old female medical student presents with fever, lack of appetite, rashes, sore throat and lymphadenopathy. Peripheral smear shows atypical lymphocytes. Which is the most likely organism responsible for this patient's condition?
Your Answer: Epstein–Barr virus
Explanation:Epstein-Barr virus is in the herpes family of viruses and most people will become infected with EBV sometime during their lives. EBV commonly causes infectious mononucleosis, or mono, a contagious viral illness that initially attacks the lymph nodes in the neck and throat. When these tissues become less effective in fighting infection, sore throats, swelling of the nodes and fever may result.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 24
Correct
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Perforin are present in the granules of which cell?
Your Answer: Natural killer cell
Explanation:Perforins are characteristically found In the granules of CD8+ T cells and natural killer cells. They are cytolytic proteins that insert into the target plasma membrane forming a hole and resulting in lysis. They along with granzyme B induce apoptosis in the target cell.
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This question is part of the following fields:
- Inflammation & Immunology
- Pathology
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Question 25
Incorrect
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A 60-year-old man complains of pain in his left thigh. An X-ray reveals bowing of the affected femur, increased bone density, bony enlargement, abnormal bone architecture with coarse cortical trabeculations, and stress microfractures. Which is the most likely diagnosis in this case?
Your Answer: Osteitis fibrosa cystica
Correct Answer: Paget’s disease of bone
Explanation:Paget’s disease of bone is a chronic disorder of the adult skeleton in which bone turnover is accelerated in localised areas, replacing normal matrix with softened and enlarged bone and causing gradual pain and deformity in some cases. It is more predominant in men over the age of 40. Characteristic X-ray findings include increased bone density, abnormal architecture with coarse cortical trabeculation or cortical thickening, bowing and bony enlargement; there might also be stress microfractures of the tibia or femur.
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This question is part of the following fields:
- Orthopaedics
- Pathology
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Question 26
Incorrect
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Extracellular body fluid as compared with intracellular body fluid:
Your Answer: Contains less chloride
Correct Answer: Is relatively rich in glucose
Explanation:The percentages of body water contained in various fluid compartments add up to total body water (TBW). This water makes up a significant fraction of the human body, both by weight and by volume. Ensuring the right amount of body water is part of fluid balance, an aspect of homeostasis. The extracellular fluid (ECF) includes all fluids outside the cells. This fluid can be divided into three fluid departments: interstitial (in the tissue spaces) fluid, blood plasma and lymph, and specialised compartments called transcellular fluid. The extracellular fluid surrounds all the cells in the body and is in equilibrium with the intracellular fluid. So, its composition must remain fairly constant even though substances are passing into and out of the cells. The interstitial fluid, though called a fluid, is in a reality a gel-like composition made up of: water, proteoglycan molecules and collagen. The extracellular fluid constitutes 40% of total body water, with intracellular fluid making up the remaining 60%. It is relatively rich in glucose.
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This question is part of the following fields:
- Fluids & Electrolytes
- Physiology
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Question 27
Correct
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A 60-year-old woman complains of left sided headaches which have been recurring for several years. She recently suffered from a focal seizure for the first time a few days ago. A CT scan shows a mass in the left hemisphere of the brain. The most likely diagnosis is:
Your Answer: Meningioma
Explanation:Meningiomas are a common benign intracranial tumour, and their incidence is higher in women between the ages of 40-60 years old. Many of these tumours are asymptomatic and are diagnosed incidentally, although some of them may have malignant presentations (less than 2% of cases). These benign tumours can develop wherever there is dura, over the convexities near the venous sinuses, along the base of the skull, in the posterior fossa and, within the ventricles.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 28
Correct
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The periphery of a haematoma is infiltrated by fibroblasts, collagen and new vasculature. This process is best described as?
Your Answer: Organisation of the haematoma
Explanation:Formation of granulation tissue at the periphery of the hematoma is a normal process leading to resolution. This granulation tissue is composed of new capillaries, fibroblasts and collagen. Lysis of a blood clot can occur, but the actual process of this response is known as organization, wherein the scar tissue will become part of the vessels. This is followed by recanalization and embolization which can lead to eventual complications. Proliferation of a clot will occur due to an imbalance in the clotting and lysing systems. Thrombosis has nothing to do with the process described above.
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This question is part of the following fields:
- Cell Injury & Wound Healing
- Pathology
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Question 29
Correct
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Which of these structures is most likely to be damaged if a patient loses consciousness days or weeks after an otherwise insignificant head trauma, especially in elderly patients?
Your Answer: Dural bridging vein
Explanation:A subdural haematoma is a type of hematoma, usually associated with traumatic brain injury, in which blood collects between the dura mater and the pia-arachnoid mater. Symptoms of subdural haemorrhage have a slower onset than those of epidural haemorrhages because the lower pressure veins bleed more slowly than arteries. These injuries are more common in elderly patients, especially those taking antiplatelet or anticoagulant drugs. Oedema and increased intracranial pressure are unusual.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 30
Correct
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An experiment is carried out to observe engulfment and phagocytosis of microbes. Strep pneumoniae are added to a solution of leukocytes with a substance added to enhance the process of phagocytosis. What is this substance?
Your Answer: Complement C3b
Explanation:C3b is cleaved from C3 complement with the help of the enzyme C3- convertase. It binds to the cell surface of the offending substance and opsonizes it. This makes it easy for the phagocytes to detect and eliminate them.
IgM does not act as an opsonin but igG does.
Selectins aid leukocytes to bind to the endothelial surfaces.
C5a is a chemo-attractant and histamine a vasodilator.
NADPH oxidises offending substance after phagocytosis within the macrophage.
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This question is part of the following fields:
- Inflammation & Immunology
- Pathology
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Question 31
Correct
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A biopsy is performed on a 67-year-old-man with testicular seminoma; it reveals that the tumour affects the tunica vaginalis. The tumour stage in this case is:
Your Answer: T2
Explanation:The primary tumour staging for testicular seminoma is as follows, according to AJCC guidelines:
Tis: intratubular germ cell neoplasia (carcinoma in situ)
T1: tumour limited to testis/epididymis without vascular or lymphatic invasion; the tumour can invade into the tunica albuginea but not the tunica vaginalis
T2: tumour limited to testis/epididymis with vascular or lymphatic invasion or tumour extending through the tunica albuginea with involvement of the tunica vaginalis
T3: tumour invading the spermatic cord, with or without vascular/lymphatic invasion
T4: tumour invading the scrotum, with or without vascular/lymphatic invasion.
According to these guidelines, the tumour in this case has a T2 stage.
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This question is part of the following fields:
- Pathology
- Urology
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Question 32
Correct
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Question 33
Correct
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The blood-brain barrier is a membrane that separates the circulating blood from the brain extracellular fluid in the central nervous system (CNS). Which of the following statements regarding the blood– brain barrier is CORRECT?
Your Answer: It breaks down in areas of brain that are infected
Explanation:The blood–brain barrier is a membrane that controls the passage of substances from the blood into the central nervous system. It is a physical barrier between the local blood vessels and most parts of the central nervous system and stops many substances from travelling across it. During meningitis, the blood–brain barrier may be disrupted. This disruption may increase the penetration of various substances (including either toxins or antibiotics) into the brain. A few regions in the brain, including the circumventricular organs, do not have a blood–brain barrier.
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This question is part of the following fields:
- Fluids & Electrolytes
- Physiology
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Question 34
Correct
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A 76 year old man who presented with lower back pain is diagnosed with prostatic carcinoma that has metastasized to his lumber spine. Which of the following markers is characteristically elevated?
Your Answer: PSA
Explanation:Spread of prostatic carcinoma is common to the lumbar spine and pelvis. This results in osteoblastic metastases that will present as lower back pain with increased alkaline phosphatase, prostatic acid phosphates and PSA. PSA is more specific and a PSA > 10 ng/ml for any age is worrisome.
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This question is part of the following fields:
- Neoplasia; Urology
- Pathology
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Question 35
Correct
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Different portions of the renal tubule have varying degrees of water permeability. Which of the following renal sites is characterised by low water permeability under normal circumstances?
Your Answer: Thick ascending limb of the loop of Henlé
Explanation:Within the nephron of the kidney, the ascending limb of the loop of Henle is a segment of the loop of Henle downstream of the descending limb, after the sharp bend of the loop. Both the thin and the thick ascending limbs of the loop of Henlé have very low permeability to water. Since there are no regulatory mechanisms to alter its permeability, it remains poorly permeable to water under all circumstances. Sodium and chloride are transported out of the luminal fluid into the surrounding interstitial spaces, where they are reabsorbed. Water must remain behind because it is not reabsorbed, so the solute concentration becomes less and less (the luminal fluid becomes more dilute). This is one of the principal mechanisms (along with diminution of ADH secretion) for the production of a dilute, hypo-osmotic urine (water diuresis).
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This question is part of the following fields:
- Physiology
- Renal
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Question 36
Incorrect
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A 44-year old man, who was euthyroid underwent thyroidectomy following neoplastic cells found on fine-needle aspiration. Frozen section of multiple thyroid masses showed malignant neoplasm of polygonal cells in nests. The neoplasm also showed presence of amyloid which was positive with Congo-red staining. Immunoperoxidase staining for calcitonin was also positive. Chest X-ray revealed no abnormality. However, his blood pressure was found to be raised, and his serum ionised calcium was high. What is the likely diagnosis?
Your Answer: Multiple endocrine neoplasia type IIB
Correct Answer: Multiple endocrine neoplasia type IIA
Explanation:MEN (Multiple Endocrine Neoplasia) syndromes are a group of three separate familial disease which consists of adenomatous hyperplasia and neoplasia in several endocrine glands. All three conditions are inherited as an autosomal dominant trait, with a single gene producing multiple effects. MEN IIA is characterized by medullary carcinoma of the thyroid, pheochromocytoma and hyperparathyroidism. It should be suspected in patients with bilateral pheochromocytoma, a familial history of MEN, or at least two characteristic endocrine manifestations. Genetic testing is used to confirm the diagnosis. Early diagnosis is crucial to aid in complete excision of the localized tumour. Pheochromocytomas can be detected by plasma free metanephrines and fractionated urinary catecholamines, particularly adrenaline (epinephrine).
Imaging studies such as computed tomography or magnetic resonance imaging might also prove useful. Hyperparathyroidism is diagnosed by the standard finding of hypercalcaemia, hypophosphatemia and an increased parathyroid hormone level. Once MEN IIA syndrome is identified in any patient, it is recommended that his or her first-degree relatives and any other symptomatic also undergo genetic testing. Relatives should be subjected to annual screening for hyperparathyroidism and pheochromocytoma beginning in early childhood and continue indefinitely. Serum calcium levels help in screening for hyperparathyroidism. Similarly, screening for pheochromocytoma is by history, measurement of the blood pressure and laboratory testing.
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This question is part of the following fields:
- Endocrine
- Pathology
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Question 37
Correct
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A 30-year-old woman feels thirsty. This thirst is probably due to:
Your Answer: Increased level of angiotensin II
Explanation:Thirst is the basic need or instinct to drink. It arises from a lack of fluids and/or an increase in the concentration of certain osmolites such as salt. If the water volume of the body falls below a certain threshold or the osmolite concentration becomes too high, the brain signals thirst. Excessive thirst, known as polydipsia, along with excessive urination, known as polyuria, may be an indication of diabetes. Angiotensin II is a hormone that is a powerful dipsogen (i.e. it stimulates thirst) that acts via the subfornical organ. It increases secretion of ADH in the posterior pituitary and secretion of ACTH in the anterior pituitary.
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This question is part of the following fields:
- Fluids & Electrolytes
- Physiology
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Question 38
Correct
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Congenital anomalies of genitourinary tract are more common than any other system. Which of the following anomalies carries the greatest risk of morbidity?
Your Answer: Bladder exstrophy
Explanation:Bladder exstrophy is the condition where the urinary bladder opens from the anterior aspect suprapubically. The mucosa of the bladder is continuous with the abdominal skin and there is separation of the pubic bones. The function of the upper urinary tract remains normal usually. Treatment consists of surgical reconstruction of the bladder and returning it to the pelvis. There can be a need for continent urinary diversion along with reconstruction of the genitals.
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This question is part of the following fields:
- Pathology
- Renal
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Question 39
Incorrect
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A 56-year-old man undergoes tests to determine his renal function. His results over a period of 24 hours were:
Urine flow rate: 2. 0 ml/min
Urine inulin: 1.0 mg/ml
Plasma inulin: 0.01 mg/ml
Urine urea: 260 mmol/l
Plasma urea: 7 mmol/l
What is the glomerular filtration rate?Your Answer: 100 ml/min
Correct Answer: 200 ml/min
Explanation:Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman’s capsule per unit time. GFR is equal to the inulin clearance because inulin is freely filtered into Bowman’s capsule but is not reabsorbed or secreted. The clearance (C) of any substance can be calculated as follows: C = (U × V)/P, where U and P are the urine and plasma concentrations of the substance, respectively and V is the urine flow rate. Thus, glomerular filtration rate = (1.0 × 2. 0)/0.01 = 200 ml/min.
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This question is part of the following fields:
- Fluids & Electrolytes
- Physiology
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Question 40
Correct
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A 55 year old man presented with a 4 day history of cough and fever. His sputum culture showed the presence of Strep pneumoniae. Which of the following substances produced by the inflammatory cells will result in effective clearance of this organism from the lung parenchyma?
Your Answer: Hydrogen peroxide
Explanation:Hydrogen peroxide is produced by myeloperoxidase to form a potent oxidant that eliminates bacteria, but is not effective in chronic granulomatous diseases.
Platelet activating factor will lead to the activation, adhesion and aggregation of platelets but will not directly kill bacteria.
Prostaglandins cause vasodilation but do not activate neutrophils.
Kallikrein promotes formation of bradykinin that leads to vasodilation.
Leukreines increase vascular permeability.
Cytokines are communicating molecules between immune cells but directly will not kill bacteria.
Interleukins will regulate the immune response.
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This question is part of the following fields:
- Inflammation & Immunology; Respiratory
- Pathology
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Question 41
Correct
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A histology report of a cervical biopsy taken from a patient with tuberculosis revealed the presence of epithelioid cells. What are these cells formed from?
Your Answer: Macrophages
Explanation:Granulomas formed in tuberculosis are called tubercles and are made up polynuclear phagocytes, Langhans cells and epithelioid cells. Macrophages when enlarged, consist of abundant cytoplasm and have a tendency of arranging themselves very closely to each other representing epithelial cells. These enlarged macrophages are therefore termed as epithelioid cells.
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This question is part of the following fields:
- Cell Injury & Wound Healing
- Pathology
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Question 42
Incorrect
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A young 16 year old boy presented to the ENT clinic with a history of sore throat for the past 1 day. On examination there was a pharyngeal purulent discharge. Which of the following types of inflammation is seen in this boy?
Your Answer: Abscess formation
Correct Answer: Acute inflammation
Explanation:A 1 day history suggests the purulent discharge is due to acute inflammation. Acute inflammation has 3 features:
1) the affected area is occupied by a purulent discharge composed of proteins, fluids and cells from local blood vessels
2) the infective agent i.e. bacteria is present in the affected area
3) the damaged tissue can be liquified and the debris removed from the site.
If the inflammation lasts over weeks or months, then it is termed as chronic inflammation.
Granulomatous inflammation is characterised by the presence and formation of granulomas.
Exudate is not a feature of resolution or a complication of inflammation.
Abscess formation takes more than 1 day to form and is usually within a capsule/cavity.
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This question is part of the following fields:
- Inflammation & Immunology; Respiratory
- Pathology
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Question 43
Correct
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A 63-year-old woman complains of a new, persisting headache. She is diagnosed with vasculitis and the histopathological sample revealed giant-cell arteritis. What is the most probable diagnose?
Your Answer: Temporal arteritis
Explanation:Giant cell arteritis (GCA), also known as temporal arteritis, is the most common systemic inflammatory vasculitis that occurs in adults. It is of unknown aetiology and affects arteries large to small however the involvement of the superficial temporal arteries is almost always present. Other commonly affected arteries include the ophthalmic, occipital and vertebral arteries, therefore GCA can result in systemic, neurologic, and ophthalmologic complications. GCA usually is found in patients older than 50 years of age and should always be considered in the differential diagnosis of a new-onset headache accompanied by an elevated erythrocyte sedimentation rate. Diagnosis depends on the results of artery biopsy.
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This question is part of the following fields:
- Cardiovascular
- Pathology
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Question 44
Correct
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Which of the following will increase blood pressure and cause hypokalaemia?
Your Answer: Angiotensin II
Explanation:Angiotensin is a peptide that is released in response to a decrease in blood volume and blood pressure. It has multiple functions but mainly acts to cause vasoconstriction, increase BP and release aldosterone from the adrenal cortex. It is a powerful vasoconstrictor and release of aldosterone causes increased retention of sodium and excretion of potassium.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 45
Incorrect
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What class of drugs does buspirone belong to?
Your Answer: Benzodiazepine
Correct Answer: Anxiolytic
Explanation:Buspirone is an anxiolytic agent and a serotonin-receptor agonist that belongs to the azaspirodecanedione class of compounds. It shows no potential for addiction compared with other drugs commonly prescribed for anxiety, especially the benzodiazepines. The development of tolerance has not been noted. It is primarily used to treat generalized anxiety disorders. It is also commonly used to augment antidepressants in the treatment of major depressive disorder.
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This question is part of the following fields:
- Pathology
- Pharmacology
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Question 46
Incorrect
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An 26-year-old man sought admission due to persistent non-bloody diarrhoea. The patient is HIV-positive. Examination of stool sample showed numerous acid-fast cysts. Which of the following organism is the most likely cause of diarrhoea?
Your Answer: Mycobacterium avium-intracellular complex
Correct Answer: Cryptosporidium parvum
Explanation:Cryptosporidium parvum is one of several species that causes cryptosporidiosis, a parasitic disease of the mammalian intestinal tract. Primary symptoms of C. parvum infection are acute, watery, and non-bloody diarrhoea. C. parvum infection is of particular concern in immunocompromised patients, where diarrhoea can reach 10–15 l per day.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 47
Correct
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During cardiac catheterisation, if the blood sample from the catheter shows an oxygen saturation of 70%, and the pressure ranging from 12 to 24 mm Hg, it implies that the catheter tip is located in the:
Your Answer: Pulmonary artery
Explanation:Normal values for various parameters are as follows:
Systolic arterial blood pressure (SBP): 90–140 mmHg.
Diastolic arterial blood pressure: 60–90 mmHg.
Mean arterial blood pressure (MAP): SBP + (2 × DBP)/3 (normal range: 70-105 mmHg).
Right atrial pressure (RAP): 2–6 mmHg.
Systolic right ventricular pressure (RVSP): 15–25 mmHg.
Diastolic right ventricular pressure (RVDP): 0–8 mmHg.
Pulmonary artery pressure (PAP): Systolic (PASP) is 15-25 mmHg and Diastolic (PADP) is 8–15 mmHg.
Pulmonary artery wedge pressure (PAWP): 6–12 mmHg.
Left atrial pressure (LAP): 6–12 mmHg.
Thus, the given value indicates that the position of catheter tip is likely to be in the pulmonary artery.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 48
Correct
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Medulloblastoma usually occurs in children between 5 to 9 years old. Where does medulloblastoma commonly originate from?
Your Answer: Cerebellar vermis
Explanation:Medulloblastoma is the most common malignant brain tumour in children, accounting for 10-20% of primary CNS neoplasms. Most of the tumours originate in the cerebellar vermis.
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This question is part of the following fields:
- Neoplasia
- Pathology
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Question 49
Correct
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The patient who is diagnosed with bladder cancer asked his physician, what could have been the contributing factor in the development of his bladder cancer?
Your Answer: Smoking
Explanation:Tobacco smoking is the main known contributor to urinary bladder cancer. In most populations, smoking is associated with over half of bladder cancer cases in men and one-third of cases among women.
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This question is part of the following fields:
- Neoplasia
- Pathology
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Question 50
Correct
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A 45-year-old man presents to the emergency department with an irregular pulse and shortness of breath. Electrocardiography findings show no P waves, normal QRS complexes and an irregularly irregular rhythm. The patient most probably has:
Your Answer: Atrial fibrillation
Explanation:Atrial fibrillation is one of the most common arrhythmias, characterised by an irregular and rapid heart rate. Due to the decreased cardiac output, atrial fibrillation increases the risk of heart failure. It can also lead to thrombus formation which may lead to thromboembolic events. Clinical findings include palpitations, shortness of breath, fatigue, chest pain and confusion. The diagnosis is made by electrocardiographic findings which include absent P wave, fibrillatory (f) waves between QRS complexes and irregularly irregular R-R intervals.
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This question is part of the following fields:
- Cardiovascular
- Pathology
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