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Question 1
Correct
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Which of the following structures is not part of the conducting system of the heart?
Your Answer: Ventricular wall
Explanation:The conduction system of the heart consists of the SA node, AV node, internodal pathway between these two nodes, Bundle of His and the purkinje fibers
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 2
Correct
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The following is true of the sinus node:
Your Answer: It generates impulses automatically & at a quicker rate than other cardiac cells
Explanation:The SA node exhibits automaticity. It generates the impulses to which the heart beats. It fires at a faster speed than the rest of the nervous components of the heart i.e. the AV nodes, purkinje fibers. This is the reason when the SA node fails the heart beats to the rhythm of the AV node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 3
Incorrect
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Which of the following is not true regarding mitochondrial chromosome disorders?
Your Answer: Retinal degeneration, diabetes mellitus and some forms of hearing loss are some of the other disease attributed to mitochondrial chromosome defects
Correct Answer: Because mitochondrial chromosomes have no introns in their genes, any point mutation has a low likelihood of having an effect.
Explanation:Mitochondrial DNA (mtDNA) does indeed lack introns, meaning that its genes are closely packed with coding sequences. This actually means that any point mutation in the mtDNA is more likely to have an effect, not less. The lack of introns means there are fewer non-coding regions where mutations can occur without affecting gene function. Thus, mutations in mtDNA often have significant consequences because they are more likely to alter essential coding sequences.
The other statements are true:
- Most mitochondrial diseases are myopathies and neuropathies with a maternal pattern of inheritance: This is correct because mtDNA is inherited maternally, and many mitochondrial disorders affect muscle and nerve function.
- Retinal degeneration, diabetes mellitus, and some forms of hearing loss are some of the other diseases attributed to mitochondrial chromosome defects: These are indeed conditions associated with mitochondrial defects.
- Mitochondrial chromosome defects are inherited from one’s mother: This is correct, as mtDNA is passed from mother to offspring.
- Leber’s hereditary optic neuropathy (LHON), the commonest cause of blindness in young men, is an example of a mitochondrial chromosome defect: This is true; LHON is a well-known mitochondrial disorder.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 4
Incorrect
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Which statement about X linked dominant disorders is FALSE?
Your Answer: Vitamin D- resistant rickets is the best known example.
Correct Answer: Heterozygous females tend to have the disease more severely than affected males.
Explanation:Women who have the affected X chromosome will be affected, but the severity will be less than that in males as they have a normal X chromosome to counter the effect of the mutated X chromosome. Affected males will pass on the defect to their daughters 100% of the time but not to their sons.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 5
Correct
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Question 6
Incorrect
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Which of the following is true of the Natriuretic hormones?
Your Answer: They are potent vasoconstrictors
Correct Answer: They are released in response to hypervolemia
Explanation:Natriuretic hormones are vasodilators released in response to hypervolemia.
Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides NPs (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain.
Atrial natriuretic peptide (ANP) plays a crucial role in blood pressure regulation by inducing natriuresis and diuresis in the kidney, inhibiting renin secretion, aldosterone production, and promoting vasorelaxation. Â Two paracrine factors derived from endothelial cells play important roles in modulating ANP secretion. Endothelin, a potent vasoconstrictor, stimulates ANP secretion and augments stretch induced ANP secretion. The dramatic increase in ANP release produced by cardiac ischemia appears to be mediated in part by endothelin. Nitric oxide (NO), an important vasodilator, is also produced by endothelial cells and inhibits ANP secretion.
Brain natriuretic peptide (BNP) shares ANP’s receptor but is primarily associated with antifibrotic effects in ventricular remodeling, serving as a biomarker for heart failure and myocardial infarction.
C-type natriuretic peptide (CNP) acts locally in an autocrine/paracrine manner, exerting potent cardiovascular effects, including vasorelaxation and vascular remodeling post-injury. NPs also demonstrate diverse effects beyond cardiovascular and renal systems, such as bronchodilation, anti-inflammatory actions, and metabolic effects on adipose tissue and long bones.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 7
Correct
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The collection of genes that are termed the major histocompatibility complex (MHC) are found on:
Your Answer: Short arm of chromosome 6
Explanation:Histocompatibility, or tissue compatibility, is the property of having the same, or sufficiently similar, alleles of a set of genes called human leukocyte antigens (HLA). HLA is the human form of the major histocompatibility complex (MHC) genes found in all vertebrates. On a population level there is a great number of different alleles at each HLA locus on the short arm of chromosome 6
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This question is part of the following fields:
- Immunology
- Medicine
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Question 8
Correct
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There is normally an inverse relationship between the hepatic artery and portal venous blood flow. This is maintained by:
Your Answer: All of the options are correct
Explanation:There is an inverse relationship between the blood flow of the hepatic artery and portal vein. It is maintained by several factors such as chemicals like adenosine, neurohumoral substances, the morphology of the hepatic portal system (especially the ability of hepatic sinusoids to collapse) and myogenic control which causes vasoconstriction or vasodilation.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 9
Incorrect
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Regarding Polymerase Chain Reaction, all are true except:
Your Answer: Is an in vitro technique
Correct Answer: There is a linear rise of DNA copies during amplification.
Explanation:All are true except there is a linear rise of DNA copies during amplification. There is an exponential rise in amplification of DNA.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 10
Incorrect
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When observing a JVP, which of the following would lead to prominent v waves?
Your Answer: Pulmonary Regurgitation
Correct Answer: Tricuspid regurgitation
Explanation:The v wave corresponds to Venous filling when the tricuspid valve is closed and venous pressure increases from venous return. In Tricuspid regurgitation there is additional blood from the regurgitant flow and thus this leads to a more prominent V wave.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 11
Incorrect
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Where is leptin synthesized and secreted?
Your Answer: Yellow adipose tissue
Correct Answer: White adipose tissue
Explanation:Leptin is a hormone that helps regulate food intake and energy expenditure. It is synthetized by white adipose tissue and the gastric mucosa. It works by inhibiting the sensation of hunger, therefore, it opposes the actions of ghrelin, also known as the hunger hormone.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 12
Correct
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A 70-year-old male with advanced COPD currently on treatment with salbutamol (as required) presents for review. After a complete history and examination, you conclude that he requires to be stepped up in his inhalational therapy. The decision to add tiotropium bromide to his regime was taken. Which of the following best describe the mechanism of action of tiotropium?
Your Answer: It is a long-acting anticholinergic agent
Explanation:Tiotropium is a specific long-acting antimuscarinic agent indicated as maintenance therapy for patients with COPD (chronic obstructive pulmonary disease). It should be used cautiously in patients with narrow-angle glaucoma, prostatic hyperplasia or bladder neck obstruction.The most frequently encountered adverse effects of tiotropium include pharyngitis, bronchitis, sinusitis, dry mouth, cough, and headaches. Paradoxical bronchospasm may also occur as a rare side-effect. Dry mouth occurs in up to 14% of patients taking tiotropium, in keeping with its anticholinergic profile. Rarer side-effects include tachycardia, blurred vision, urinary retention, and constipation.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 13
Incorrect
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A 20-year-old male presents to the emergency department about 4 hours after ingesting 20g of paracetamol. N-acetyl cysteine was started immediately. What is the mechanism of action of N-acetyl cysteine?
Your Answer: Neutralises mercapturic acid
Correct Answer: Replenishes glutathione
Explanation:N-acetylcysteine depletes glutathione reserves by providing cysteine, which is an essential precursor in glutathione production.Glutathione within the liver can normally detoxify these minuscule quantities of NAPQI and prevent tissue damage.N-acetylcysteine (NAC) is the mainstay of therapy for acetaminophen toxicity.Paracetamol overdose:The liver normally conjugates paracetamol with glucuronic acid/sulphate. During an overdose, the conjugation system becomes saturated leading to oxidation by cytochrome P450 (predominately CYP2E1) mixed-function oxidases. This produces a toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI).Normally glutathione acts as a defence mechanism by conjugating with the toxin forming the non-toxic mercapturic acid. If glutathione stores run-out, the toxin forms covalent bonds with cell proteins, denaturing them and leading to cell death.Other uses: In COPD, cystic fibrosis, and other lung conditions, nebulized NAC has mucolytic, anti-inflammatory, and antioxidant properties.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 14
Incorrect
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Regarding gustatory sensation:
Your Answer: Fungiform papillae are rounded structures arranged in a v on the back of the tongue
Correct Answer: The sensory taste buds on the anterior two-thirds of the tongue travel to the chorda tympani branch of the facial nerve
Explanation:There are three morphologically distinct types of taste buds including; circumvallate, fungiform and foliate. Circumvallate are rounded structures arranged in a v on the back of the tongue. The posterior third travels to glossopharyngeal nerve.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 15
Incorrect
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A son has brought his 72-year-old mother to clinic. He is concerned about her short-term memory problems for the past 10 months. He has to remind her to take her medications and she has had two incidents of falling over in the last 10 months. Which of the following assists in the diagnosis of above condition?
Your Answer: Disinhibition
Correct Answer: Progressive loss of function
Explanation:The clinical presentation is dementia. To differentiate Alzheimer disease and vascular dementia, the progressive loss of function is important. Progressive loss of function is usually associated with vascular dementia and rest of the responses are associated with Alzheimer disease.
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This question is part of the following fields:
- Geriatrics
- Medicine
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Question 16
Incorrect
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In the olfactory pathway: Mitral cells project to five regions of the olfactory cortex. Which one of the following is not one of the five regions?
Your Answer: Amygdala
Correct Answer: Posterior olfactory nucleus
Explanation:The olfactory system contains peripheral and central divisions which are connected by transduction structures. Peripheral division consists mainly of the nostrils, ethmoid bone, nasal cavity, and the olfactory epithelium. Olfactory neurons are receptor cells in the epithelium that detect odour molecules dissolved in the mucus and transmit information about the odour to the brain in a process called sensory transduction. Olfactory nerves and fibers transmit information about odours from the peripheral olfactory system to the central olfactory system of the brain. The main olfactory bulb transmits pulses to both mitral and tufted cells, which help determine odour concentration. These cells also note differences between highly similar odours and use that data to aid in later recognition. The cells are different with the mitral having low firing-rates and being easily inhibited by neighbouring cells, while tufted have high rates of firing and are more difficult to inhibit. The uncus houses the olfactory cortex which includes the piriform cortex, amygdala, olfactory tubercle, and para-hippocampal gyrus. Entorhinal cortex is an area of middle temporal lobe that has connection with the para-hippocampal gyrus.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 17
Correct
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Wernicke’s area:
Your Answer: Is concerned with comprehension of auditory and visual information
Explanation:Wernicke’s area is located in the categorical hemisphere or left hemisphere in about 95% of right handed individuals and 60% of left handed individuals. It is involved in the comprehension or understanding of written and spoken language. In contrast Broca’s area is involved in production of language.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 18
Incorrect
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All of the following are Vitamin K-dependent clotting factors except:
Your Answer: Protein S
Correct Answer: Factor XI
Explanation:Activated Vitamin K is used to gamma carboxylate (and thus activate) certain enzymes involved in coagulation: Factors II, VII, IX, X, and protein C and protein S. Inability to activate the clotting cascade via these factors leads to the bleeding symptoms
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This question is part of the following fields:
- Haematology
- Medicine
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Question 19
Correct
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The primary sensory cortex is:
Your Answer: Brodmann area 3,1,2
Explanation:A Brodmann area in the brain is defined by cytoarchitecture, histology and organization of cells:Primary somatosensory cortex is areas 3,1, and 2Primary Motor 4Premotor 6Primary Visual 17Primary Auditory 41Brocas 44
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This question is part of the following fields:
- Medicine
- Neurology
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Question 20
Incorrect
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Question 21
Incorrect
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Which of the following is a form of synaptic plasticity?
Your Answer: Neurogenesis
Correct Answer: Working memory
Explanation:Synaptic plasticity is an important neurochemical foundation of working memory and generation of memory. Synaptic plasticity is the ability of synapses to strengthen or weaken over time in response to increases or decreases in their activity.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 22
Incorrect
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A 52-year-old man has squamous-cell carcinoma of his lower lip. Which of the following is most likely to be a feature of this type of carcinoma?
Your Answer: It is unrelated to sun exposure
Correct Answer: It is capable of metastasising via the lymphatics
Explanation:Squamous-cell skin cancer usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months and it is more likely to spread to distant areas than basal cell cancer vie the lymphatics. The greatest risk factor is high total exposure to ultraviolet radiation from the Sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen’s disease, arsenic exposure, radiation therapy, poor immune system function, previous basal cell carcinoma, and HPV infection. While prognosis is usually good, if distant spread occurs five-year survival is ,34%
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 23
Incorrect
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The processing of NH3 to urea occurs in:
Your Answer: Mitochondria alone
Correct Answer: Mitochondria and cytoplasm
Explanation:The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea ((NH2)2CO) from ammonia (NH3). The urea cycle consists of four enzymatic reactions: one mitochondrial and three cytosolic.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 24
Correct
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Afferent fibers from the baroreceptors of the great arteries form branches of which cranial nerves?
Your Answer: Glossopharyngeal and vagus nerves
Explanation:The receptors of the carotid sinus are innervated by the carotid sinus nerve, a branch of the glossopharyngeal nerve. The aortic arch receptors located in the arch of the aorta are innervated by the aortic depressor nerve, a branch of the vagus nerve.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 25
Incorrect
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Which one of the following neurotransmitters is considered a monoamine?
Your Answer: Glutamate
Correct Answer: Dopamine
Explanation:Monoamines are a class of neurotransmitters that include:
- Dopamine: A neurotransmitter involved in reward, motivation, and motor control.
- Norepinephrine: A neurotransmitter involved in arousal, attention, and stress responses.
- Serotonin: Although not listed in the options, it is another key monoamine involved in mood regulation.
The other neurotransmitters listed are not monoamines:
- Acetylcholine: This is a different type of neurotransmitter involved in muscle activation and various brain functions.
- GABA (gamma-aminobutyric acid): This is the main inhibitory neurotransmitter in the central nervous system.
- Glutamate: This is the main excitatory neurotransmitter in the central nervous system.
- Glycine: An inhibitory neurotransmitter in the central nervous system.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 26
Correct
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Which enzyme deficiency can lead to ammonia intoxication?
Your Answer: Ornithine transcarbamylase
Explanation:Ornithine transcarbamylase deficiency also known as OTC deficiency is the most common urea cycle disorder in humans. Ornithine transcarbamylase, the defective enzyme in this disorder is the final enzyme in the proximal portion of the urea cycle, responsible for converting carbamoyl phosphate and ornithine into citrulline. OTC deficiency is inherited in an X-linked recessive manner, meaning males are more commonly affected than females.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 27
Incorrect
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In meiosis, the period of prophase 1 involves:
Your Answer: The production of two identical daughter cells
Correct Answer: Replicated DNA condensing to form visible chromosomes
Explanation:Prophase 1 has been divided into five different stages (laptotene, zygotene, pachytene, diplotene and diakinesis). In prophase 1, chromosomes are going to condense to become visible, each chromosome will contain two chromatids that are joined at the centromere.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 28
Incorrect
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Which of the following corresponds to an oblique line drawn from the sternal end of the left 3rd costal cartilage to the sternal end of the right 6th costal cartilage?
Your Answer: Inter-ventricular septum
Correct Answer: Atrio-ventricular (coronary) groove
Explanation:The AV groove corresponds to the right border of the heart. The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 29
Incorrect
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What is the mechanism of action of carbimazole?
Your Answer: Inhibition of 5'-deiodinase
Correct Answer: Inhibition of the iodination of tyrosine
Explanation:Carbimazole is used to treat hyperthyroidism. Carbimazole is a pro-drug as after absorption it is converted to the active form, methimazole. Methimazole prevents thyroid peroxidase enzyme from coupling and iodinating the tyrosine residues on thyroglobulin, hence reducing the production of the thyroid hormones T3 and T4 (thyroxine).
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 30
Correct
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Humoral immunity is a major defence against:
Your Answer: Viral infections
Explanation:Humoral immunity is provided by the neutralizing and non-neutralizing antibodies that are formed from the B lymphocytes. This form of immunity is most important in viral infection. Non-neutralizing antibodies increases phagocytosis of the infected cell and inhibit the ability of the virus to replicate.
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This question is part of the following fields:
- Immunology
- Medicine
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