-
Question 1
Incorrect
-
Which of the following occurs at the transverse thoracic plane:
Your Answer: Azygos vein drains into subclavian vein
Correct Answer: Bifurcation of the trachea
Explanation:A way to help remember the structures transected by the transverse thoracic plane is CLAPTRAP:
C: cardiac plexus
L: ligamentum arteriosum
A: aortic arch (inner concavity)
P: pulmonary trunk
T: tracheal bifurcation (carina)
R: right-to-left movement of the thoracic duct (posterior to the oesophagus)
A: azygos vein drains into superior vena cava
P: pre-vertebral fascia and pre-tracheal fascia end -
This question is part of the following fields:
- Anatomy
- Thorax
-
-
Question 2
Incorrect
-
All of the following statements regarding metronidazole are correct except:
Your Answer:
Correct Answer: Metronidazole reduces the anticoagulant effect of warfarin.
Explanation:The anticoagulant effect of warfarin is enhanced by metronidazole. If use of both cannot be avoided, one must consider appropriately reducing the warfarin dosage. With alcohol, metronidazole can cause a disulfiram-like reaction, with symptoms like flushing, headaches, dizziness, tachypnoea and tachycardia, nausea and vomiting. The common side effects of metronidazole include a metallic taste and gastrointestinal irritation, in particular nausea and vomiting. These side effects are more common at higher doses. This drug has high activity against anaerobic bacteria and protozoa, and is well absorbed orally. For severe infections, the intravenous route is normally reserved.
-
This question is part of the following fields:
- Infections
- Pharmacology
-
-
Question 3
Incorrect
-
Glucagon is the main catabolic hormone of the body and raises the concentration of glucose and fat in the bloodstream.
Which pancreatic islet cells secretes glucagon?Your Answer:
Correct Answer: Alpha
Explanation:Glucagon, secreted from the pancreatic islet alpha cells, is considered to be the main catabolic hormone of the body. It raises the concentration of glucose and fat in the bloodstream
There are five different pancreatic islet cells:
Alpha cells (20%) – produce glucagon
Beta cells (70%) – produce insulin and amylin
Delta cells (<10%) – produce somatostatin
Gamma cells (<5%) – produce pancreatic polypeptide
Epsilon cells (<1%) – produce ghrelin -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
-
-
Question 4
Incorrect
-
A 42-year-old woman with a history of hyposplenism arrives at the Emergency Department sick and feverish. A complete set of bloods, including a peripheral blood film, is organised.
On a hyposplenic blood film, which of the following features is LEAST likely to be seen?Your Answer:
Correct Answer: Teardrop cells
Explanation:The collection of abnormalities found in these patients is referred to as a hyposplenic film.
The following features can be seen on hyposplenic blood films:
Howell-Jolly bodies
Heinz’s bodies
Target cells
RBCs with nuclei on occasion
Lymphocytosis
Macrocytosis
Acanthocytes
Teardrop cells, also known as dacrocytes, are named for their teardrop-shaped shape.Dacrocytosis is a condition in which a large number of these cells are present. Myelofibrosis and beta thalassemia major both have dacrocytes, but hyposplenism does not.
-
This question is part of the following fields:
- Haematology
- Pathology
-
-
Question 5
Incorrect
-
A 4-year-old child has been convulsing for 20 minutes. She has received two doses of lorazepam. She takes phenytoin for maintenance therapy, and you draw up a phenobarbitone infusion.
What dose of phenobarbitone is advised in the treatment of the convulsing child that reaches that stage of the APLS algorithm? Select ONE answer only.Your Answer:
Correct Answer: 20 mg/kg over 30-60 minutes
Explanation:If a convulsing child reaches step 3 of the APLS algorithm, then a phenytoin infusion should be set up at 20 mg/kg over 20 minutes. If they are already taken phenytoin as maintenance therapy, then a phenobarbitone infusion should be set up at 20 mg/kg over 30-60 minutes.
-
This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
-
-
Question 6
Incorrect
-
Polyuria and polydipsia develop in a patient with a history of affective disorder, who has been on long-term lithium treatment. She has a fluid deprivation test done because she is suspected of having nephrogenic diabetic insipidus. Which of the following urine osmolality findings would be the most reliable in confirming the diagnosis?
Your Answer:
Correct Answer: After fluid deprivation <300 mosmol/kg, after IM desmopressin >800 mosmol/kg
Explanation:The inability to produce concentrated urine is a symptom of diabetes insipidus. Excessive thirst, polyuria, and polydipsia are all symptoms of this condition. There are two forms of diabetes insipidus: Nephrogenic diabetes insipidus and cranial (central) diabetes insipidus.
A lack of ADH causes cranial diabetic insipidus. Patients with cranial diabetes insipidus can have a urine output of up to 10-15 litres per 24 hours, however most patients can maintain normonatraemia with proper fluid consumption. Thirty percent of cases are idiopathic, while another thirty percent are caused by head injuries. Neurosurgery, brain tumours, meningitis, granulomatous disease (e.g. sarcoidosis), and medicines like naloxone and phenytoin are among the other reasons. There is also a very rare hereditary type that is linked to diabetes, optic atrophy, nerve deafness, and bladder atonia.
Renal resistance to the action of ADH causes nephrogenic diabetes insipidus. Urine output is significantly increased, as it is in cranial diabetes insipidus. Secondary polydipsia can keep serum sodium levels stable or raise them. Chronic renal dysfunction, metabolic diseases (e.g., hypercalcaemia and hypokalaemia), and medications, such as long-term lithium use and demeclocycline, are all causes of nephrogenic diabetes insipidus.
The best test to establish if a patient has diabetes insipidus vs another cause of polydipsia is the water deprivation test, commonly known as the fluid deprivation test. It also aids in the distinction between cranial and nephrogenic diabetes insipidus. Weight, urine volume, urine osmolality, and serum osmolality are all measured after patients are denied water for up to 8 hours. At the end of the 8-hour period, 2 micrograms of IM desmopressin is given, and measures are taken again at 16 hours.
The following are the way results are interpreted:
Urine osmolality after fluid deprivation : Urine osmolality after IM desmopressin
Cranial diabetes insipidus: <300 mosmol/kg : >800 mosmol/kg
Nephrogenic diabetes insipidus: <300 mosmol/kg : <300 mosmol/kg
Primary polydipsia: >800 mosmol/kg : >800 mosmol/kg -
This question is part of the following fields:
- Physiology
- Renal Physiology
-
-
Question 7
Incorrect
-
A 55-year-old woman with history of gastritis and reflux esophagitis tested positive for Helicobacter pylori infection.
Which of the following statements regarding Helicobacter pylori is considered true?Your Answer:
Correct Answer: It is helix shaped
Explanation:Helicobacter pylori is a curved or helix-shaped, non-spore forming, Gram-negative, microaerophilic bacteria. It is motile, having multiple flagella at one pole. It has a lipopolysaccharide component in its outer membrane.
-
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
-
-
Question 8
Incorrect
-
Which of the following is not true regarding the structure and function of glomerular filtration membrane?
Your Answer:
Correct Answer: The absence of a basement membrane reduces impedance to filtration
Explanation:The glomerular filtration membrane is composed of fenestrated capillary endothelium, basement membrane, and filtration slits. It is an organized, semipermeable membrane preventing the passage of most of the proteins into the urine.
The anatomical arrangement of the glomerular filtration membrane maximizes the surface area available for filtration. The arrangement of its arterioles results in high hydrostatic pressures and facilitates filtration.
Fenestrated capillary endothelium of the glomerular filtration membrane is with relatively large pores. It allows the free movement of plasma proteins and solutes but still restricts the movement of blood cells.
Filtration slits are the smallest filters and restrict the movement of plasma proteins but still allow free movement of ions and nutrients.
The glomerular basement membrane (GBM) is a critical component of the glomerular filtration membrane. Thus, it is not true that its absence will reduce the resistance of flow. The basement membrane is true to be more selective and contains negatively charged glycoproteins. However, it still allows free passage of water, nutrients, and ions. Severe structural abnormalities of the GBM can result in protein (albumin) leakage.
-
This question is part of the following fields:
- Physiology
- Renal Physiology
-
-
Question 9
Incorrect
-
Which ONE statement about homeostasis is true?
Your Answer:
Correct Answer: Negative feedback occurs via receptors, comparators and effectors
Explanation:Homeostasis is the property of a system in which variables are regulated so that internal conditions remain relatively constant and stable. Homeostasis is achieved by a negative feedback mechanism.
Negative feedback occurs based upon a set point through receptors, comparators and effectors.
The ‘set point’ is a NARROW range of values within which normal function occurs.
The two body systems that regulate homeostasis are the Nervous system and the Endocrine system.
The smooth muscle of the uterus becomes more active towards the end of pregnancy. This is a POSITIVE feedback.
-
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
-
-
Question 10
Incorrect
-
A 13-year-old male presents to the Emergency Department with a heavy nosebleed. His medical record shows that he was diagnosed with Haemophilia B as a child.
What is the mode of inheritance of this disease?Your Answer:
Correct Answer: X-linked recessive
Explanation:Deficiency of Factor IX causes Haemophilia B, and like the other Haemophilia’s, it has an X-linked recessive pattern of inheritance, affecting males born to carrier mothers.
Haemophilia B is the second commonest form of haemophilia and is rarer than haemophilia A. Haemophilia B is similar to haemophilia A but is less severe. You can distinguish the two disorders by specific coagulation factor assays.
The incidence of Haemophilia B is one-fifth of that of haemophilia A.
In laboratory findings, you get prolonged APTT, normal PT and low factor IX for Haemophilia B.
There is also a variation called Leyden, in which factor IX levels are below 1% until puberty, when they rise, potentially reaching as high as 40-60% of normal. This is thought to be due to the effects of testosterone at puberty.
-
This question is part of the following fields:
- Haematology
- Pathology
-
-
Question 11
Incorrect
-
At the start of the cardiac cycle, towards the end of diastole, all of the following statements are true EXCEPT for:
Your Answer:
Correct Answer: The semilunar valves are open.
Explanation:At the start of the cardiac cycle, towards the end of diastole, the whole of the heart is relaxed. The atrioventricular (AV) valves are open because the atrial pressure is still slightly greater than the ventricular pressure. The semilunar valves are closed, as the pressure in the pulmonary artery and aorta is greater than the ventricular pressures. The cycle starts when the sinoatrial node (SAN) initiates atrial systole.
-
This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 12
Incorrect
-
Regarding meningococcal meningitis, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Infection occurs most commonly below the age of 5 years.
Explanation:About half of meningococcal disease occurs in children aged less than five years, and babies are at the highest risk because their immune systems have not yet fully developed. There is a second, smaller increase in risk for older adolescents, mainly for social and behavioural reasons. Infection is most common in winter months. Antibiotics should be given as soon as the diagnosis is suspected (ideally cultures should be performed first but this should not delay treatment), and ceftriaxone/cefuroxime is the first line antibiotic. Only healthcare workers who have been directly exposed to large particle droplets/secretions from the respiratory tract of the index case should receive prophylaxis.
-
This question is part of the following fields:
- Microbiology
- Pathogens
-
-
Question 13
Incorrect
-
Regarding the flexor digitorum profundus muscle, which of the following is true?
Your Answer:
Correct Answer: The medial aspect of the muscle is innervated by the ulnar nerve
Explanation:Flexor digitorum profundus is a fusiform muscle located deep within the anterior (flexor) compartment of the forearm. Along with the flexor pollicis longus and pronator quadratus muscles, it comprises the deep flexor compartment of the forearm.
Flexor digitorum profundus has a dual innervation:
(1) The medial part of the muscle, that inserts to the fourth and fifth digits, is innervated by the ulnar nerve (C8-T1);
(2) The lateral part, that inserts to the second and third digits, is innervated by the median nerve, via anterior interosseous branch (C8-T1).
-
This question is part of the following fields:
- Anatomy
- Upper Limb
-
-
Question 14
Incorrect
-
Which of the following laboratory findings are suggestive of functional hyposplenism:
Your Answer:
Correct Answer: Howell-Jolly bodies
Explanation:Functional hyposplenism is characterised by the blood film findings of Howell-Jolly bodies or siderotic granules on iron staining. The most frequent cause is surgical removal of the spleen e.g. after traumatic rupture, but hyposplenism can also occur in sickle cell anaemia, gluten-induced enteropathy, amyloidosis and other conditions.
-
This question is part of the following fields:
- Immune Responses
- Pathology
-
-
Question 15
Incorrect
-
A well recognised adverse effect of metoclopramide is which of the following?
Your Answer:
Correct Answer: Acute dystonic reaction
Explanation:Side effects of metoclopramide are commonly associated with extrapyramidal effects and hyperprolactinemia. Therefore its use must be limited to short-term use. Metoclopramide can induce acute dystonic reactions which involve facial and skeletal muscle spasms and oculogyric crises. These dystonic effects are more common in the young girls and young women, and in the very old. These symptoms usually occur shortly after starting treatment with this drug and subside within 24 hours of stopping it. Abortion of dystonic attacks can be carried out by injection of an antiparkinsonian drug like procyclidine.
-
This question is part of the following fields:
- Central Nervous System
- Pharmacology
-
-
Question 16
Incorrect
-
Regarding antimuscarinic antispasmodics, which of the following statements is CORRECT:
Your Answer:
Correct Answer: They are contraindicated in paralytic ileus.
Explanation:Antimuscarinics are contraindicated in paralytic ileus. Antimuscarinics reduce intestinal motility by blocking muscarinic acetylcholine receptors and relaxing smooth muscle. Hyoscine butylbromide is advocated as a gastrointestinal antispasmodic, but it is poorly absorbed and thus has limited clinical utility. Antimuscarinics cause a reduction in bronchial secretions (they can be used to this effect in palliative patients). Antispasmodics are occasionally of value in treating abdominal cramp associated with diarrhoea but they should not be used for primary treatment. Antispasmodics should be avoided in young children with gastroenteritis because they are rarely effective and have troublesome side effects.
-
This question is part of the following fields:
- Gastrointestinal
- Pharmacology
-
-
Question 17
Incorrect
-
A 20-year-old patient had sustained a supracondylar fracture due to falling from a skateboard. The frequency of acute nerve injuries accompanying supracondylar humeral fractures ranges from 10 to 20%. The most common complication is injury to which nerve?
Your Answer:
Correct Answer: Median nerve
Explanation:According to various studies, the frequency of acute nerve damage associated with supracondylar humeral fractures in children ranges from 10% to 20%.
Median nerve injury and anterior interosseous nerve injury are the most common consequences.
Damage to this nerve indicated weakening or abnormal extension of the index finger’s distal interphalangeal joint and the thumb’s interphalangeal joint. The absence of sensibility is a distinguishing attribute.
A surgical neck humerus fracture may cause injury to the axillary nerve. A midshaft humerus fracture might cause injury to the radial nerve. A medial epicondylar fracture might cause injury to the ulnar nerve.
-
This question is part of the following fields:
- Anatomy
- Upper Limb
-
-
Question 18
Incorrect
-
A 55-year-old woman was complaining of headaches. On examination, the patient is found to have weakness on the left side of her body and her eyes are deviated towards the right hand side. These are signs of damage to which of the following areas?
Your Answer:
Correct Answer: Frontal lobe
Explanation:Some potential symptoms of frontal lobe damage can include loss of movement, either partial or complete, on the opposite side of the body.
In the patient’s case, it is a result of motor cortex damage on the right side since her left side of the body is affected. The conjugate eye deviation symptom towards the side of the lesion is a result of damage to the frontal eye field.
-
This question is part of the following fields:
- Anatomy
- Central Nervous System
-
-
Question 19
Incorrect
-
A 57-year-old woman receives vitamin B12 injections following a gastrectomy.
Which of the following cell types, if absent, is responsible for her vitamin B12 deficiency?Your Answer:
Correct Answer: Parietal cells
Explanation:Intrinsic factor, produced by the parietal cells of the stomach, is essential for the absorption of vitamin B12 from the terminal ileum.
After a gastrectomy, the absorption of vitamin B12 is markedly reduced, and a deficiency will occur. -
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
-
-
Question 20
Incorrect
-
Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:
Your Answer:
Correct Answer: In relaxation, Ca 2+ is transported out of the cell using energy from a Na + gradient.
Explanation:During the AP plateau, Ca2+enters the cell and activates Ca2+sensitive Ca2+release channels in the sarcoplasmic reticulum allowing stored Ca2+to flood into the cytosol; this is called Ca2+-induced Ca2+release. In relaxation, about 80% of Ca2+is rapidly pumped back into the SR (sequestered) by Ca2+ATPase pumps. The Ca2+that entered the cell during the AP is transported out of the cell primarily by the Na+/Ca2+exchanger in the membrane which pumps one Ca2+ion out in exchange for three Na+ions in, using the Na+electrochemical gradient as an energy source. Increased heart rate increases the force of contraction in a stepwise fashion as intracellular [Ca2+] increases cumulatively over several beats; this is the Treppe effect. Factors that affect intracellular [Ca2+] and hence cardiac contractility are called inotropes.
-
This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 21
Incorrect
-
Question 22
Incorrect
-
Question 23
Incorrect
-
Identify the type of graph described below:
A graph that consists of a vertical bar graph in which values are plotted in decreasing order of relative frequency from left to right. The independent variables on the chart are shown on the horizontal axis and the dependent variables are portrayed as the heights of bars.Your Answer:
Correct Answer: Pareto diagram
Explanation:A pareto diagram, or pareto chart, consists of a vertical bar graph in which values are plotted in decreasing order of relative frequency from left to right. The independent variables on the chart are shown on the horizontal axis and the dependent variables are portrayed as the heights of bars.
A point-to-point graph, which shows the cumulative relative frequency, may be superimposed on the bar.
Because the values of the statistical variables are placed in order of relative frequency, the graph clearly reveals which factors have the greatest impact and where attention is likely to yield the greatest benefit. It is extremely useful for analysing what problems need attention first, because the taller bars on the chart clearly illustrate which variable have the greatest cumulative effect on a given system.
-
This question is part of the following fields:
- Evidence Based Medicine
-
-
Question 24
Incorrect
-
On review of a patient's serum and urine osmolality test result, you note that both osmolarities are decreased. There urine osmolality does not increase with fluid ingestion.
What is the most likely cause?Your Answer:
Correct Answer: Hyponatraemia
Explanation:As part of the investigation of hyponatraemia, serum osmolality is commonly requested in combination with urine osmolality to aid diagnosis.
When:
Serum osmolality is decreased and urine osmolality is decreased with no intake of fluid, the causes are
Hyponatraemia
Overhydration
Adrenocortical insufficiency
Sodium loss (diuretic or a low-salt diet)Serum osmolality is normal or increased and urine osmolality is increased the causes include:
Dehydration
Hyperkalaemia
Hyperglycaemia
Hyponatremia
Mannitol therapy
Diabetes mellitus
Alcohol ingestion
Congestive heart failure
Renal disease and uraemiaSerum osmolality is normal or increased and urine osmolality is decreased the usual cause is diabetes insipidus
Serum osmolality is decreased and urine osmolality is increased the usual cause is syndrome of inappropriate antidiuresis (SIAD)
-
This question is part of the following fields:
- Basic Cellular Physiology
- Physiology
-
-
Question 25
Incorrect
-
A 33-year-old female, who recently returned from a trip to Bangladesh, presents to the infectious diseases clinic with complaints of productive cough with blood-stained sputum, night sweats, and weight loss for the past one month. Based on the history and examination findings, you suspect pulmonary tuberculosis.
Which ONE of the following investigations is most appropriate to make a diagnosis of active tuberculosis?Your Answer:
Correct Answer: Sputum for acid-fast bacilli smear
Explanation:Multiple investigations may be done to establish a diagnosis of active tuberculosis. In this case, sputum for acid-fast bacilli would be the best option as it can be done immediately, give fast results, and promptly initiate treatment. Three-morning sputum samples are collected and tested for acid-fast bacilli using gram staining.
Blood culture would yield results in tuberculous bacteraemia and would be less sensitive than sputum testing.
A chest X-ray would not differentiate active tuberculosis from an old infection in which the Ghon complex has formed, and the body’s immune reaction contains the Mycobacterium tuberculosis bacteria.
Mantoux test shows the presence of antibodies to tuberculosis and may be positive if the patient has had a previous infection or been vaccinated against tuberculosis.
A CT chest would also be unable to differentiate between an active infection and the findings of old tuberculosis infection.
-
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
-
-
Question 26
Incorrect
-
An increased anion gap metabolic acidosis is typically caused by which of the following?
Your Answer:
Correct Answer: Propylene glycol overdose
Explanation:Causes of a raised anion gap acidosis can be remember using the mnemonic MUDPILES:
-Methanol
-Uraemia (in renal failure)
-Diabetic ketoacidosis
-Propylene glycol overdose
-Infection/Iron overdose/Isoniazid/Inborn errors of metabolism
-Lactic acidosis
-Ethylene glycol overdose
-Salicylate overdose -
This question is part of the following fields:
- Physiology
- Renal
-
-
Question 27
Incorrect
-
Which of the following statements is correct regarding the neuronal action potential?
Your Answer:
Correct Answer: Initial depolarisation occurs as a result of a Na + influx.
Explanation:The resting potential in most neurons has a value of approximately -70 mV.
The threshold potential is generally around -55 mV.
Initial depolarisation when there is Na+influx through ligand-gated Na+channels.
Action potential is an all or nothing response. The size of the action potential is constant and so, the intensity of the stimulus is coded by the frequency of firing of a neuron.
K+efflux is responsible for repolarisation. -
This question is part of the following fields:
- Basic Cellular
- Physiology
-
-
Question 28
Incorrect
-
Excessive gastric acid output is detected in a patient with a history of recurrent stomach ulcers. It's possible that the patient has Zollinger-Ellison syndrome.
Which of the following statements about stomach acid is correct?Your Answer:
Correct Answer: The proton pump located in the canalicular membrane is vital to its secretion
Explanation:The stomach produces gastric acid, which is a digesting fluid. The stomach secretes about 2-3 litres every day. It is involved in tissue breakdown, the conversion of pepsinogen to active pepsin, and the creation of soluble salts with calcium and iron, and has a pH range of 1.5-3.5. It also serves as an immune system by destroying microbes.
The following substances are found in gastric acid:
Water
Acid hydrochloride
Pepsinogen
mucous
Intrinsic factorThe parietal cells in the proximal 2/3 (body) of the stomach release gastric acid. The concentration of hydrogen ions in parietal cell secretions is 1-2 million times that of blood. Chloride is released against both a concentration and an electric gradient, and active transport is required for the parietal cell to produce acid.
The following is how stomach acid is secreted:
1. Gastric acid secretion is dependent on the H+/K+ ATPase (proton pump) situated in the canalicular membrane. The breakdown of water produces hydrogen ions within the parietal cell. The hydroxyl ions produced in this reaction mix quickly with carbon dioxide to generate bicarbonate ions. Carbonic anhydrase is the enzyme that catalyses this process.
2. In return for chloride, bicarbonate is carried out of the basolateral membrane. The ‘alkaline tide’ occurs when bicarbonate is released into the bloodstream, resulting in a modest rise in blood pH. The parietal cell’s intracellular pH is maintained by this procedure. Conductance channels carry chloride and potassium ions into the lumen of canaliculi.
3. Through the action of the proton pump, hydrogen ions are pushed out of the cell and into the lumen in exchange for potassium; potassium is thus efficiently recycled.
4. The canaliculi accumulate osmotically active hydrogen ions, which creates an osmotic gradient across the membrane, allowing water to diffuse outward.
-
This question is part of the following fields:
- Gastrointestinal Physiology
- Physiology
-
-
Question 29
Incorrect
-
In the ventricular myocyte action potential, depolarisation occurs through the opening of:
Your Answer:
Correct Answer: Voltage-gated Na + channels
Explanation:An action potential (AP) is initiated when the myocyte is depolarised to a threshold potential of about -65 mV, as a result of transmission from an adjacent myocyte via gap junctions. Fast voltage-gated Na+channels are activated and a Na+influx depolarises the membrane rapidly to about +30 mV. This initial depolarisation is similar to that in nerve and skeletal muscle, and assists the transmission to the next myocyte.
-
This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 30
Incorrect
-
A 55-year-old female is urgently rushed into the Emergency Department as she complains of chest pain that is worse on breathing, shortness of breath, palpitations, and haemoptysis.
She undergoes a CT pulmonary angiogram, which reveals a large pulmonary embolus. She is immediately started on heparin and shifted to the acute medical ward.
Which of the following does heparin activate?Your Answer:
Correct Answer: Antithrombin III
Explanation:Heparin works by binding to and activating the enzyme inhibitor antithrombin III.
Antithrombin III inactivates thrombin (factor IIa) by forming a 1:1 complex with thrombin. The heparin-antithrombin III complex also inhibits factor Xa and some other proteases involved with clotting. The heparin-ATIII complex can also inactivate IX, XI, XII, and plasmin.
Heparin is a polymer of glycosaminoglycan. It occurs naturally and is found in mast cells. Clinically, it is used in two forms:
1. Unfractionated: widely varying polymer chain lengths
2. Low molecular weight: Smaller polymers onlyHeparin is not thrombolytic or fibrinolytic. It prevents the progression of existing clots by inhibiting further clotting. The lysis of existing clots relies on endogenous thrombolytics.
Heparin is used for:
1. Prevention and treatment of venous thromboembolism
2. Treatment of disseminated intravascular coagulation
3. Treatment of fat embolism
4. Priming of haemodialysis and cardiopulmonary bypass machines -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
-
SESSION STATS - PERFORMANCE PER SPECIALTY
