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Question 1
Correct
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What will the destruction of endoplasmic reticulum stop?
Your Answer: Synthesis of proteins
Explanation:The rough endoplasmic reticulum is the factory for the manufacturing of proteins. It contains ribosomes attached to it and transports proteins that are destined for membranes and secretions. The rough ER is connected to the nuclear envelope and to the cisternae of the Golgi apparatus by vesicles that shuttle between the two compartments.
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This question is part of the following fields:
- General
- Physiology
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Question 2
Correct
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Which of the following is a potential cause of a positive D-dimer assay?
Your Answer: Deep venous thrombosis
Explanation:A D-dimer test is performed to detect and diagnose thrombotic conditions and thrombosis. A negative result would rule out thrombosis and a positive result although not diagnostic, is highly suspicious of thrombotic conditions like a deep vein thrombosis, pulmonary embolism as well as DIC.
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This question is part of the following fields:
- General
- Physiology
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Question 3
Correct
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Myoglobin is released as a result of rhabdomyolysis from damaged skeletal muscles. What function do they perform in the muscle?
Your Answer: Acts like haemoglobin and binds with O2
Explanation:Myoglobin is a pigmented globular protein made up of 153 amino acids with a prosthetic group containing haem around which the apoprotein folds. It is the primary oxygen carrying protein of the muscles. The binding of oxygen to myoglobin is unaffected by the oxygen pressure as it has an instant tendency to bind given its hyperbolic oxygen curve. It releases oxygen at very low pO2 levels.
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This question is part of the following fields:
- General
- Physiology
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Question 4
Correct
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A patient admitted for esophagectomy showed low levels of the lightest plasma protein in terms of weight. Which of the following is the lightest plasma protein:
Your Answer: Albumin
Explanation:Albumin is the most abundant and the lightest of all the plasma proteins. It maintains osmotic pressure, transports unconjugated bilirubin, thyroid hormones, fatty acids, drugs and acts as a buffer for pH.
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This question is part of the following fields:
- General
- Physiology
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Question 5
Incorrect
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A patient came into the emergency in a state of shock. His blood group is not known, but on testing it clotted when mixed with Type A antibodies. Which blood should be transfused?
Your Answer: A +ve
Correct Answer: B +ve
Explanation:There are two stages to determine the blood group, known as ABO typing. The first stage is called forward typing. In this method, RBCs are mixed with two separate solutions of type A or type B antibodies to see if they agglutinate. If this blood clumps, this indicates the presence of antigens within the blood sample. For example, a sample of type B blood will clump when tested with type A antibodies as it contains type B antigens. Group B – has only the B antigen on red cells (and A antibody in the plasma)
Group B – has only the B antigen on red cells (and A antibody in the plasma)
Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma)
Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma). Many people also have a Rh factor on the red blood cell’s surface. This is also an antigen and those who have it are called Rh+. Those who have not are called Rh–. A person with Rh– blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance) but they can develop Rh antibodies in the blood plasma if they receive blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh– blood without any problems. The patient’s blood group is B positive as he has antigen B, antibody A and Rh antigens.
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This question is part of the following fields:
- General
- Physiology
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Question 6
Incorrect
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Which of the following can lead to haemolytic anaemia?
Your Answer: Intrinsic factor deficiency
Correct Answer: Presence of haemoglobin S
Explanation:Haemoglobin S is an abnormal type of haemoglobin seen in sickle cell anaemia. This allows for the haemoglobin to crystalize within the RBC upon exposure to low partial pressures of oxygen. This results in rupture of the RBCs as they pass through microcirculation, especially in the spleen. This can cause blockage of the vessel down stream and ischaemic death of tissues, accompanied by severe pain.
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This question is part of the following fields:
- General
- Physiology
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Question 7
Incorrect
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What is the reason for a deranged thrombin clotting time?
Your Answer: von Willebrand’s disease
Correct Answer: Heparin therapy
Explanation:Thrombic clotting time is also known as thrombin time. It is clinically performed to determine the therapeutic levels of heparin. After plasma is isolated from the blood, bovine thrombin is added to it and the time it takes from the addition to clot is recorded. The reference interval is usually <21s. deranged results are indicative of heparin therapy, hypofibrinogenemia, hyperfibrinogenaemia or lupus anticoagulant.
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This question is part of the following fields:
- General
- Physiology
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Question 8
Correct
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Electrophoresis is used to detect antibodies (immunoglobulins) in a blood sample from the umbilical artery of a new born. Which antibodies have the highest percentage in a new-born?
Your Answer: IgG
Explanation:IgG is a monomeric immunoglobulin. It is formed by two heavy chains and two light chains and has two binding sites. Its is the most abundant antibody that is equally distributed in the blood and the tissues. It is the only antibody that can pass through the placenta and thus the only antibody present in the baby after it is born. There are four subclasses: IgG1 (66%), IgG2 (23%), IgG3 (7%) and IgG4 (4%). IgG1, IgG3 and IgG4 cross the placenta easily
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This question is part of the following fields:
- General
- Physiology
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Question 9
Incorrect
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A 65-year old patient with altered bowl movement experienced the worsening of shortness of breath and exertional chest pains over the course of 8 weeks. Examination shows pallor and jugular venous distension. Furthermore, a test of the stool for occult blood is positive. Laboratory studies show:
Haemoglobin 7.4 g/dl
Mean corpuscular volume 70 fl Leukocyte count 5400/mm3
Platelet count 580 000/mm3 Erythrocyte sedimentation 33 mm/h
A blood smear shows hypochromic, microcytic RBCs with moderate poikilocytosis. Which of the following is the most likely diagnosis?Your Answer: Anaemia of chronic disease
Correct Answer: Iron deficiency anaemia
Explanation:Iron deficiency anaemia is the most common type of anaemia. It can occur due to deficiency of iron due to decreased intake or due to faulty absorption. An MCV less than 80 will indicated iron deficiency anaemia. On the smear the RBC will be microcytic hypochromic and will also show piokilocytosis. iron profiles tests are important to make a diagnosis. Clinically the patient will be pale and lethargic.
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This question is part of the following fields:
- General
- Physiology
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Question 10
Correct
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Skeletal muscle fibres are divided into two basic types, type I (slow-twitch fibres) and type II (fast-twitch fibres). Fast muscle fibres do which of the following:
Your Answer: Use anaerobic metabolism
Explanation:Skeletal muscles are divided into two types:
1) type I also known as the slow twitch fibres. They use oxygen for their metabolism and as a result they have a high endurance potential. To support this they have abundant mitochondria and myoglobin, so they appear red/dark.
2) type II fibres also called fast twitch fibres, are low endurance fibres used during anaerobic metabolism. They are required for short bursts of strength and cannot sustain contractions for long periods of time.
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This question is part of the following fields:
- General
- Physiology
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Question 11
Correct
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A syndrome responsible for failure to absorb vitamin B12 from the GIT is called?
Your Answer: Pernicious anaemia
Explanation:Pernicious anaemia is a type of autoimmune disease in which antibodies form against the parietal cells or intrinsic factor. Intrinsic factor is required for the absorption of vitamin B12. Blood testing typically shows a macrocytic, normochromic anaemia and low levels of serum vitamin B12. A Schilling test can then be used to distinguish between pernicious anaemia, vitamin B12 malabsorption and vitamin B12 deficiency. Symptoms include shortness of breath, pallor and diarrhoea etc.
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This question is part of the following fields:
- General
- Physiology
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Question 12
Incorrect
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A blood sample of a 58 year old male patient, who underwent an abdominal aortic aneurysm repair, was sent to the laboratory. The laboratory technician said that the patient’s blood agglutinates with antisera anti-A and anti-D, while the patient’s serum agglutinates cells of blood group B. What is the blood group of this patient?
Your Answer: AB positive
Correct Answer: A positive
Explanation:Group A – has only the A antigen on red cells (and B antibody in the plasma)
Group B – has only the B antigen on red cells (and A antibody in the plasma)
Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma)
Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma). Many people also have a so-called Rh factor on the red blood cell’s surface. This is also an antigen and those who have it are called Rh+. A person with Rh– blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance) but they can develop Rh antibodies in the blood plasma if they receive blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh– blood without any problems. In this scenario the person has blood group A+ as he has A antigen, anti B antibody and Rh antigen
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This question is part of the following fields:
- General
- Physiology
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Question 13
Incorrect
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Selective destruction of which of the following cells will affect antibody synthesis?
Your Answer: T lymphocytes
Correct Answer: Plasma cells
Explanation:Plasma cell are memory cells. After the antigen Is engulfed by the B cells it is presented to the CD4+ helper cells via the MCH II receptor and this leads to their activation which in turn stimulates the B cells to form antibodies against that specific antigen. Some B cells differentiate into plasma cells also called memory cells that get activated after subsequent infection.
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This question is part of the following fields:
- General
- Physiology
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Question 14
Correct
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An 18 year-old with an iron deficient diet was prescribed an iron supplement by her GP. Lack of iron often results in:
Your Answer: Hypochromic anaemia
Explanation:Iron deficiency anaemia is the most common type of anaemia. It can occur due to deficiency of iron from decreased intake, increased loss or inadequate absorption. An MCV less than 80 will indicated iron deficiency anaemia. On the smear the RBCs will be microcytic hypochromic and will also show poikilocytosis. Iron profile tests are important to make a diagnosis. Clinically the patient will be pale and lethargic.
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This question is part of the following fields:
- General
- Physiology
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Question 15
Incorrect
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A 26-year-old female patient had the following blood report: RBC count = 4. 0 × 106/μl, haematocrit = 27% and haemoglobin = 11 g/dl, mean corpuscular volume (MCV) = 80–100 fl, mean corpuscular haemoglobin concentration (MCHC) = 31–37 g/dl. Which of the following is correct regarding this patient’s erythrocytes:
Your Answer: Decreased MCHC
Correct Answer: Normal MCV
Explanation:MCV is the mean corpuscular volume and it is calculated from the haematocrit and the RBC count. It is normally 90 fl. Mean corpuscular haemoglobin concentration (MCHC) [g/dl] = haemoglobin [g/dl]/haematocrit = 11/0.27 = 41 g/dl and is higher than normal range (32 to 36 g/dL).
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This question is part of the following fields:
- General
- Physiology
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Question 16
Incorrect
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A 23 year old woman is Rh -ve and she delivered a baby with a Rh+ blood group. What measure can be performed to prevent Rh incompatibility in the next pregnancy?
Your Answer: Corticosteroids
Correct Answer: Immunoglobulin D
Explanation:Rh disease is also known as erythroblastosis fetalis and is a disease of the new-born. In mild states it can cause anaemia with reticulocytosis and in severe forms causes severe anaemia, morbus hemolytcus new-born and hydrops fetalis. RBCs of the Rh+ baby can cross the placenta and enter into the maternal blood. As she is Rh- her body will form antibodies against the D antigen which will pass through the placenta in subsequent pregnancies.
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This question is part of the following fields:
- General
- Physiology
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Question 17
Incorrect
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What is the role of factor VII in coagulation?
Your Answer: Deficiency is common
Correct Answer: Initiates the process of coagulation in conjunction with tissue factor
Explanation:The main role of factor VII is to initiate the process of coagulation along with tissue factor (TF). TF is found in the blood vessels and is not normally exposed to the bloodstream. When a vessel is injured tissue factor is exposed to blood and circulating factor VII. Factor VII is converted to VIIa by TF.
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This question is part of the following fields:
- General
- Physiology
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Question 18
Incorrect
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A 50 year old man was admitted to the surgical ICU following a hemicolectomy for carcinoma of the caecum. A full blood count revealed: haematocrit = 30%, erythrocytes = 4 × 106/μ, haemoglobin level = 8 g/dl. To determine the likely cause of his anaemia, red blood cell indices were calculated. Which RBC indices are correct?
Your Answer: MCHC = haemoglobin concentration × 10/erythrocyte number
Correct Answer: MCHC = haemoglobin concentration/haematocrit
Explanation:Mean corpuscular haemoglobin concentration (MCHC) is calculated simply by dividing the haemoglobin concentration (8 g/dl) by the haematocrit (0.3). The normal range is 31–36 g/dl. This patient has a hypochromic anaemia (MCHC = 8/0.3 = 26.7 g/dl). Dividing the haemoglobin concentration × 10 by erythrocyte number yields mean corpuscular haemoglobin (MCH). Normal range is 25.4–34.6 pg/cell and this patient has a significantly reduced cellular haemoglobin content (MCH = 8 × 10/4 = 20 pg/cell). Mean corpuscular volume (MCV) is calculated by dividing haematocrit × 1000 by erythrocyte number (4 × 106/μl). Normal range is 80–100 fl and this patient has a microcytic anaemia (MCV = 0.3 × 1000/4 = 75 fl). Microcytic, hypochromic anaemia is characteristic for iron-deficiency.
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This question is part of the following fields:
- General
- Physiology
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Question 19
Incorrect
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Which of the following associations is correctly matched with the body's defence mechanism in fighting infection?
Your Answer: First line of defence → lymphocytes
Correct Answer: Specific cellular mechanism → cytotoxic T cells
Explanation:The immune system has certain levels of defence against pathogens. First line includes simple barriers such as skin, mucosa and stomach acid that prevent the pathogen from entering into the body. If this barrier is breached then the innate immune system is activated which includes leukocytes (macrophages, neutrophils, mast cells, eosinophils, basophils, natural killer cells). If the pathogens invade the second layer of defence then the third layer, adaptive immunity is activated, which includes B and T lymphocytes. B cells provide a humoral response whereas cytotoxic T cells have specific cellular mechanisms. They maintain a memory of past infections and are activated faster following a recurrence.
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This question is part of the following fields:
- General
- Physiology
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Question 20
Correct
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An experiment was conducted in which the skeletal muscle protein (not smooth muscle) involved in contraction was selectively inhibited. Which protein was inhibited?
Your Answer: Troponin
Explanation:The mechanism of contraction of smooth muscles is different from that of skeletal muscles in which the contractile protein is troponin whilst in smooth muscle contraction is a protein called calmodulin. Calmodulin reacts with calcium ions and stimulates the formation of myosin crossbridges.
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This question is part of the following fields:
- General
- Physiology
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Question 21
Incorrect
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Which of the following proteins prevents red blood cells (RBCs) from bursting when they pass through capillaries?
Your Answer: Actin
Correct Answer: Spectrin
Explanation:Spectrin is a structural protein found in the cytoskeleton that lines the intercellular side of the membrane of cells which include RBCs. They maintain the integrity and structure of the cell. It is arranged into a hexagonal arrangement formed from tetramers of spectrin and associated with short actin filaments that form junctions allowing the RBC to distort its shape.
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This question is part of the following fields:
- General
- Physiology
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Question 22
Incorrect
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A 26-year-old female patient had the following blood report: RBC count = 4. 0 × 106/μl, haematocrit = 27% and haemoglobin = 11 g/dl, mean corpuscular volume (MCV) = 90 fl, mean corpuscular haemoglobin concentration (MCHC) = 41 g/dl. Further examination of blood sample revealed increased osmotic fragility of the erythrocytes. Which of the following is the most likely cause of this patient’s findings?
Your Answer: Iron-deficiency anaemia
Correct Answer: Spherocytosis
Explanation:Spherocytes are small rounded RBCs. It is due to an inherited defect of the RBC cytoskeleton membrane tethering proteins. Membrane blebs form that are lost over time and cells become round instead of biconcave. As it is a normochromic anaemia, the MCV is normal. it is diagnosed by osmotic fragility test which reveals increased fragility in a hypotonic solution.
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This question is part of the following fields:
- General
- Physiology
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Question 23
Incorrect
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During pregnancy the uterus enlarges however after delivery it regresses to its original size. Which of the following organelles is responsible for this regression?
Your Answer: Centrioles
Correct Answer: Lysosomes
Explanation:Lysosomes are formed by budding of the Golgi apparatus and contain enzymes which digest macromolecules. They are found in both plants and animals and are active in autophagic cell death, digestion after phagocytosis and for the cells own recycling process. They fuse with the molecules and release their content resulting in digestion.
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This question is part of the following fields:
- General
- Physiology
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Question 24
Correct
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A 25 year old man presented with a history of headache and peripheral cyanosis. He had been living in the Himalayas for 6 months prior to this. What is the reason for his condition?
Your Answer: Physiological polycythaemia
Explanation:Polycythaemia is a condition that results in an increase in the total number of red blood cells (RBCs) in the blood. It can be due to myeloproliferative syndrome or due to chronically low oxygen levels or rarely malignancy. In primary polycythaemia/polycythaemia vera the increase is due to an abnormality in the bone marrow, resulting in increases RBCs, white blood cells (WBCs) and platelets. In secondary polycythaemia the increase occurs due to high levels of erythropoietin either artificially or naturally. The increase is about 6-8 million/cm3 of blood. A type of secondary polycythaemia is physiological polycythaemia where people living in high altitudes who are exposed to hypoxic conditions produce more erythropoietin as a compensatory mechanism for thin oxygen and low oxygen partial pressure.
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This question is part of the following fields:
- General
- Physiology
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Question 25
Incorrect
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The gradual depolarization in-between action potentials in pacemaker tissue is a result of?
Your Answer: A gradual change in the ratio of extracellular to intracellular ion concentration across the cell membrane
Correct Answer: A combination of gradual inactivation outward IK along with the presence of an inward ‘funny’ current (If) due to opening of channels permeable to both Na+ and K+ ions
Explanation:One of the characteristic features of the pacemaker cell is the generation of a gradual diastolic depolarization also called the pacemaker potential. In phase 0, the upstroke of the action potential caused by an increase in the Ca2+ conductance, an influx of calcium occurs and a positive membrane potential is generated. The next is phase 3 which is repolarization caused by increased K+ conductance as a result of outwards K+ current. Phase 4 is a slow depolarization which accounts for the pacemaker activity, caused by increased conductance of Na+, inwards Na+ current called IF. it is turned on by repolarization.
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This question is part of the following fields:
- General
- Physiology
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Question 26
Correct
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A 30 year old female suffered from mismatched transfusion induced haemolysis. Which substance will be raised in the plasma of this patient?
Your Answer: Bilirubin
Explanation:Bilirubin is a yellow pigment that is formed due to the break down of RBCs. Haemolysis results in haemoglobin that is broken down into a haem portion and globin which is converted into amino acids and used again. Haem is converted into unconjugated bilirubin in the macrophages and shunted to the liver. In the liver it is conjugated with glucuronic acid making it water soluble and thus excreted in the urine. Its normal levels are from 0.2-1 mg/dl. Increased bilirubin causes jaundice and yellowish discoloration of the skin.
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This question is part of the following fields:
- General
- Physiology
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Question 27
Incorrect
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A blood sample from a patient with polycythaemia vera will show which of the following abnormalities?
Your Answer: Low red blood cell count
Correct Answer: High platelet count
Explanation:Polycythaemia is a condition that results in an increase in the total number of red blood cells (RBCs) in the blood. It can be due to a myeloproliferative syndrome, chronically low oxygen levels or rarely malignancy. In primary polycythaemia/ polycythaemia vera the increase is due to an abnormality in the bone marrow, resulting in increased RBCs, white blood cells (WBCs) and platelets. In secondary polycythaemia the increase occurs due to high levels of erythropoietin either artificially or naturally. The increase is about 6-8 million/cm3 of blood. A type of secondary polycythaemia is physiological polycythaemia where people living in high altitudes who are exposed to hypoxic conditions produce more erythropoietin as a compensatory mechanism for thin oxygen and low oxygen partial pressure.
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This question is part of the following fields:
- General
- Physiology
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Question 28
Incorrect
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Action potentials are used extensively by the nervous system to communicate between neurones and muscles or glands. What happens during the activation of a nerve cell membrane?
Your Answer: Sodium ions flow outward
Correct Answer: Sodium ions flow inward
Explanation:During the generation of an action potential, the membrane gets depolarized which cause the voltage gated sodium channels to open and sodium diffuses inside the neuron, resulting in the membrane potential moving towards a positive value. This positive potential will then open the voltage gated potassium channels and cause more K+ to move out decreasing the membrane potential and restoring the membrane potential to its resting value.
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This question is part of the following fields:
- General
- Physiology
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Question 29
Incorrect
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What is the mostly likely cause of prolonged activated partial thromboplastin time (aPPT) ?
Your Answer: Liver disease
Correct Answer: Heparin therapy
Explanation:The partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT) is an indicator for measuring the efficacy of both the intrinsic and common coagulation pathway. Prolonged aPTT may indicate: use of heparin, antiphospholipid antibody and coagulation factor deficiency (e.g., haemophilia). Deficiencies of factors VIII, IX, XI and XII and rarely von Willebrand factor (if causing a low factor VIII level) may lead to a prolonged aPTT correcting on mixing studies.
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This question is part of the following fields:
- General
- Physiology
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Question 30
Incorrect
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Regarding the coagulation cascade, Factor VII:
Your Answer: Is mainly synthesised by the vascular endothelium
Correct Answer: Is a serine protease
Explanation:Factor VII (FVII) is a zymogen for a vitamin K-dependent serine protease essential for the initiation of blood coagulation. It is synthesized primarily in the liver and circulates in plasma. Within the liver, hepatocytes are involved in the synthesis of most blood coagulation factors, such as fibrinogen, prothrombin, factor V, VII, IX, X, XI, XII, as well as protein C and S, and antithrombin, whereas liver sinusoidal endothelial cells produce factor VIII and von Willebrand factor.
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This question is part of the following fields:
- General
- Physiology
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Question 31
Correct
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A 50 year old woman presented with excessive bleeding after an inguinal hernia repair. Labs are suggestive of a primary haemostasis defect. Deficiency of which of the following is most likely to cause it?
Your Answer: Platelets
Explanation:Primary haemostatic control means the first line of defence against immediate bleeding. This is carried out by the platelets. They immediately form a haemostatic plug at the site of injury. Coagulation starts within 20s after an injury to the blood vessel which damage the endothelial cells. Secondary haemostasis follows which includes activation of the coagulation factors to form fibrin strands which mesh together forming the platelet plug. Platelets interact with platelet collagen receptor, glycoprotein Ia/IIa and to collagen fibres in the vascular endothelium. This adhesion is mediated by von Willebrand factor (vWF), which forms links between the platelet glycoprotein Ib/IX/V and collagen fibrils. The platelets are then activated and release the contents of their granules into the plasma, in turn activating other platelets and white blood cells.
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This question is part of the following fields:
- General
- Physiology
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Question 32
Incorrect
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what is the cause of a prolonged PT(prothrombin time)?
Your Answer: von Willebrand factor deficiency
Correct Answer: Liver disease
Explanation:PT measure the intrinsic pathway of coagulation. It determines the measure of the warfarin dose regime, liver disease and vit K deficiency status along with the clotting tendency of blood. PT measured factors are II,V,VII,X and fibrinogen. It is used along with aPTT which measure the intrinsic pathway.
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This question is part of the following fields:
- General
- Physiology
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Question 33
Correct
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C5a (a complement component) is a potent?
Your Answer: Anaphylotoxin
Explanation:C5a is a strong chemoattractant as well as an anaphylotoxin and is involved in the recruitment of inflammatory cells such as neutrophils, eosinophils, monocytes, and T lymphocytes. It is also involved in activation of phagocytic cells, release of granule-based enzymes and generation of oxidants. All of which contribute to innate immune functions.
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This question is part of the following fields:
- General
- Physiology
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Question 34
Correct
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Which of the following organelles have the capacity to regenerate and spontaneously replicate?
Your Answer: Mitochondrion
Explanation:A mitochondria is a membrane bound organelle found in eukaryotic cells. They are called the powerhouse of the cell and are the place where ATP is formed from energy generated through metabolism. They are capable of replication as well as repair and regeneration.
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This question is part of the following fields:
- General
- Physiology
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Question 35
Incorrect
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Which statement is correct regarding coagulation?
Your Answer: Vitamin K is an essential co-factor for hepatic synthesis of factor VIII
Correct Answer: Thrombin converts fibrinogen to fibrin
Explanation:Coagulation of blood is a complex process and an important part of haemostasis. There are two main pathways related to coagulation: the contact activation pathway/intrinsic pathway and tissue factor/extrinsic pathway. The extrinsic pathway is activated by external trauma that causes blood to escape from the vascular system. This pathway is quicker than the intrinsic pathway and involves factor VII. The intrinsic pathway is activated by trauma inside the vascular system, and initiated by platelets, exposed endothelium, chemicals, or collagen. This pathway is slower than the extrinsic pathway, but more important. It involves factors XII, XI, IX, VIII. Both pathways meet to finish the formation of a clot in what is known as the common pathway. The common pathway involves factors I, II, V, and X. They converge on the common pathway in which activation of prothrombin to thrombin leads to conversion of fibrinogen to fibrin and clot formation.
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This question is part of the following fields:
- General
- Physiology
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Question 36
Correct
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The mechanism of action of streptokinase involves:
Your Answer: Direct conversion of plasminogen to plasmin
Explanation:Streptokinase is an enzyme that is produced by group A beta haemolytic streptococcus and is an effective and cost efficient method for the dissolution of a clot used in cases of MI and pulmonary embolism. It works by directly converting plasminogen to plasmin which breaks down the blood components in the clot and fibrin, dissolving the clot. Streptokinase is a bacterial product and thus the body will develop immunity against it.
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This question is part of the following fields:
- General
- Physiology
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Question 37
Incorrect
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Which of the following organs is most likely to have dendritic cells?
Your Answer: Heart
Correct Answer: Skin
Explanation:Dendritic cells are part of the immune system and they function mainly as antigen presenting cells. They are present in small quantities in tissues which are in contact in the external environment. Mainly in the skin and to a lesser extent in the lining of the nose, lungs, stomach and intestines. In the skin they are known as Langerhans cells.
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This question is part of the following fields:
- General
- Physiology
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Question 38
Incorrect
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Most of the coagulation factors are serine proteases. Which of the following is not one of them?
Your Answer: Factor II
Correct Answer: Factor XIII
Explanation:Serine protease coagulation factors include: thrombin, plasmin, Factors X, XI and XII. Factor VIII and factor V are glycoproteins and factor XIII is a transglutaminase.
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This question is part of the following fields:
- General
- Physiology
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Question 39
Correct
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A 38-year-old woman with end-stage renal disease, is undergoing haemodialysis. She has normocytic normochromic anaemia. What is the best treatment for her?
Your Answer: Erythropoietin
Explanation:E erythropoietin (EPO) is a hormone that is released by the kidney. It is responsible for the regulation of red blood cell production in the body. It can be made using recombinant technology and is used in the treatment of anaemia of chronic renal failure and in patients under going chemotherapy
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This question is part of the following fields:
- General
- Physiology
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Question 40
Incorrect
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A 50 year old man on warfarin therapy following insertion of a pacemaker presented with epistaxis. Which of the following is true regarding blood coagulation?
Your Answer: von Willebrand factor suppresses blood coagulation
Correct Answer: Patients with haemophilia A usually have a normal bleeding time
Explanation:A prolonged bleeding time is seen in platelet disorders like thrombocytopenia. Patients with haemophilia A or B have a prolonged PTT but not a prolonged bleeding time.
Ca2+ is necessary for coagulation.
von Willebrand factor is an important part of the factor VIII complex and promotes platelet adhesion and aggregation.
DIC results in depleted coagulation factors and accumulation of fibrin.
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This question is part of the following fields:
- General
- Physiology
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Question 41
Incorrect
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After having donated a unit of blood. The blood bank will prefer to use which of the following anticoagulants to store the blood?
Your Answer: Ferrioxamine
Correct Answer: Citrate
Explanation:Calcium is necessary for coagulation to occur. Citrate being a chelator and combining with calcium ions to form un-ionised compound will prevent coagulation. Following transfusion the citrate is removed by the liver with in a few minutes. Oxalate also works on the same principle but it is toxic to the body.
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This question is part of the following fields:
- General
- Physiology
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Question 42
Incorrect
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Atractyloside is an inhibitor of electron transport chain. It is expected to have little or no effect on the functioning of which of the following cell types?
Your Answer: Parotid duct cells
Correct Answer: Red blood cells
Explanation:Electron transport chain is a series of electron carriers that are embedded in the mitochondrial membrane. It is the place where ATP is made. Inhibiting the electron transport chain will stop production of ATP. Red blood cells are the only cell in the given option which do not contain ATP.
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This question is part of the following fields:
- General
- Physiology
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Question 43
Incorrect
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Which of the following cytokines produced by the T cell induce MHC-II proteins?
Your Answer: Tumour necrosis factor
Correct Answer: γ-Interferon
Explanation:Interferons elicit a non-specific antiviral activity by inducing specific RNA synthesis and expression of proteins in neighbouring cells. Common interferon inducers are viruses, double-stranded RNA and micro-organisms. INF-γ is produced mainly by CD4+, CD8+ T cells and less commonly by B cells and natural killer cells. INF-γ has antiviral and antiparasitic activity but its main biological activity appears to be immunomodulatory. Among its many functions are activation of macrophages and enhanced expression of MHC-II proteins or macrophages.
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This question is part of the following fields:
- General
- Physiology
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Question 44
Incorrect
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Depression of the normal coagulation system and excessive bleeding after surgery can occur in which of the following medical conditions?
Your Answer: Heart disease
Correct Answer: Liver disease
Explanation:As most of the coagulation factors are synthesized in the liver, liver diseases like hepatitis or cirrhosis will depress the coagulation system. Vitamin K deficiency can also decrease the production of vitamin K dependent coagulation factors VII, XI, X and prothrombin.
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This question is part of the following fields:
- General
- Physiology
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Question 45
Correct
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The transmembrane proteins responsible for resting membrane potential of vascular smooth muscle cells was blocked by a drug. Which of the following transmembrane proteins were blocked by this drug?
Your Answer: K+ channels
Explanation:The resting membrane potential is due to selective permeability of the membrane to potassium ions. The Na/K pump is responsible for the generation of a gradient across the membrane and it is due to the inherent ability of the K channels to allow diffusion back into the nerve at rest which charges the cells. In reality, the resting membrane potential is more positive because of small contributions by Na+ channels, Cl− channels and non-selective cation channels.
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This question is part of the following fields:
- General
- Physiology
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Question 46
Incorrect
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A 47 year-old woman was admitted for elective cholecystectomy, with a past history of easy bruising and heavy menstrual periods. The patient was also diagnosed with Willebrand's disease. Willebrand's disease is:
Your Answer: Y-linked
Correct Answer: Autosomal dominant
Explanation:von Willebrand disease is an autosomal dominant disorder marked by the deficiency of vWF, a large protein synthesized by the endothelial cells and megakaryocytes. It mediates adhesion of platelets to the subendothelium at site of vascular injury. Disease characteristics include impaired platelet adhesion, prolonged bleeding time and a functional deficiency of factor VIII (vWF is its carrier protein).
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This question is part of the following fields:
- General
- Physiology
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Question 47
Incorrect
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Which of the following is true regarding factor XI?
Your Answer: Is produced by platelets
Correct Answer: Deficiency causes haemophilia C
Explanation:Factor XI is also known as plasma thromboplastin and is one of the enzymes of the coagulation cascade. It is produced in the liver and is a serine protease. It is activated by factor XIIa, thrombin and by itself. Deficiency of factor XI causes the rare type of haemophilia C. Low levels of factor XI also occur in other disease states, including Noonan syndrome. High levels of factor XI have been seen in thrombosis.
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This question is part of the following fields:
- General
- Physiology
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Question 48
Correct
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A young women following a road traffic accident suffered heavy blood loss and developed subsequent anaemia. Which of the following is a consequence of this?
Your Answer: A high reticulocyte count
Explanation:Anaemia refers to a decrease in the circulating levels of haemoglobin in the blood resulting in a reduced ability of the body to transport oxygen effectively. Anaemia from blood loss results in the body further compensating by releasing stored RBCs and immature RBCs from the bone marrow. Thus resulting in a high reticulocyte count.
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This question is part of the following fields:
- General
- Physiology
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Question 49
Incorrect
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A teenage Somalian boy presents with a complaint of an enlarged lower jaw. His blood film shows blast cells and macrophages. Which virus is responsible for this?
Your Answer: Coxsackie B virus
Correct Answer: Epstein–Barr virus
Explanation:Burkitt’s lymphoma is a type of non-Hodgkin’s lymphoma. Histologically it is characterised by a starry sky appearance due to numerous neoplastic macrophages which are required to clear the rapidly dividing tumour cells/blast cells. Burkitt’s lymphoma commonly affects the jaw bone, forming a huge tumour mass. It is associated with translocation of c-myc gene and has three types: 1) endemic/African type, 2)sporadic and 3)immunodeficiency-associated. The first type is strongly associated with EBV.
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This question is part of the following fields:
- General
- Physiology
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Question 50
Incorrect
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Where is factor VIII predominantly synthesised?
Your Answer:
Correct Answer: Vascular endothelium
Explanation:Factor VIII is an important part of the coagulation cascade. Deficiency causes haemophilia A. It is synthesised predominantly by the vascular endothelium and is not affected by liver disease. In the circulation it is bound to von Willebrand factor and it forms a stable complex with it. It is activated by thrombin or factor Xa and acts as a co factor to factor IXa to activate factor X which is a co factor to factor Va. Thrombin cleaves fibrinogen in fibrin and forms a meshwork to trap RBC and platelets to form a clot.
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This question is part of the following fields:
- General
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
