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Question 1
Incorrect
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Cardiac muscle and skeletal muscle are alike, but there are a few key variations. Which of the following is NOT a characteristic of skeletal muscle but is a characteristic of cardiac muscle?
Your Answer: Striation of cells
Correct Answer: The presence of intercalated discs
Explanation:Cardiac muscle is striated, and the sarcomere is the contractile unit, similar to skeletal muscle. Contracture is mediated by the interaction of calcium, troponins, and myofilaments, much as it occurs in skeletal muscle. Cardiac muscle, on the other hand, differs from skeletal muscle in a number of ways. In contrast to skeletal muscle cells, cardiac myocytes have a nucleus in the middle of the cell and sometimes two nuclei. The cells are striated because the thick and thin filaments are arranged in an orderly fashion, although the arrangement is less well-organized than in skeletal muscle. Intercalated discs, which work similarly to the Z band in skeletal muscle in defining where one cardiac muscle cell joins the next, are a very significant component of cardiac muscle. Adherens junctions and desmosomes, which are specialized structures that hold the cardiac myocytes together, are formed by the transverse sections. The lateral sections produce gap junctions, which join the cytoplasm of two cells directly, allowing for rapid action potential conduction. These critical properties allow the heart to contract in a coordinated manner, allowing for more efficient blood pumping. Cardiac myocytes have the ability to create their own action potentials, which is referred to as myogenic’. They can depolarize spontaneously to initiate a cardiac action potential. Pacemaker cells, as well as the sino-atrial (SA) and atrioventricular (AV) nodes, control this. The Purkinje cells and the cells of the bundle of His are likewise capable of spontaneous depolarization. While the bundle of His is made up of specialized myocytes, it’s vital to remember that Purkinje cells are not myocytes and have distinct characteristics. They are larger than myocytes, with fewer filaments and more gap junctions than myocytes. They conduct action potentials more quickly, allowing the ventricles to contract synchronously. Cardiac myocytes contract by excitation-contraction coupling, just like skeletal myocytes. Heart myocytes, on the other hand, utilise a calcium-induced calcium release mechanism that is unique to cardiac muscle (CICR). The influx of calcium ions (Ca2+) into the cell causes a ‘calcium spark,’ which causes more ions to be released into the cytoplasm. An influx of sodium ions induces an initial depolarisation, much as it does in skeletal muscle; however, in cardiac muscle, the inflow of Ca2+ sustains the depolarisation, allowing it to remain longer. Due to potassium ion (K+) inflow, CICR causes a plateau phase in which the cells remain depolarized for a short time before repolarizing. Skeletal muscle, on the other hand, repolarizes almost instantly. Comparison of skeletal and cardiac muscle: Skeletal muscle Cardiac muscle Striation Striated but arrangement less organised Multiple nuclei located peripherally Usually single nucleus (but can be two), located centrally Discs None Intercalated discs No Gap junctions Gap junctions No Pacemaker Pacemaker Electrical stimulation: Nervous system (excitation) Pacemaker (excitation)
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 2
Incorrect
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The following determines the strength of contraction
Your Answer: Resting membrane potential
Correct Answer: Plateau phase
Explanation:The plateau phase which follows is unique to myocytes and results from a small, but sustained inward calcium current through L-type calcium channels lasting 200-400 ms. This calcium influx is caused by a combined increase in permeability of the cell and especially the sarcolemmal membranes to calcium. This plateau (or refractory) phase in myocyte action potential prevents early reactivation of the myocytes and directly determines the strength of contraction
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 3
Incorrect
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Following a bee sting, a women develops a 2cm red, raised, swollen lesion at the site of the sting . Which of the following findings is likely to be seen in this lesion?
Your Answer: Neutrophilic migration
Correct Answer: Vasodilation
Explanation:Inflammation is the immediate response of the body towards infections or irritations. The cardinal signs of inflammation are 1. redness/rubor, 2. tumour/swelling, 3.dolar/pain, 4.calor/heat and organ dysfunction (function laesa). Inflammation has 2 components; vascular and cellular. Blood vessels dilate upstream of the inflamed area leading to the rubor and calor and constrict downstream, increasing pressure and causing fluid to leak out of the capillary, resulting in swelling. The cellular component includes infiltration by neutrophils. Leukocyte arrival and functions include; 1. margination: cells marginated from the centre to the periphery of the vessel, 2. rolling: selectins are upregulated on the vessel walls, 3. adhesion: upregulation of the adhesion molecules ICAM and VCAM on the endothelium interact with integrins on the leukocytes resulting in adhesion, 4. diapedesis and chemotaxis: diapedesis is the transmigration of the leukocyte across the endothelium of the capillary and towards a chemotactic product and 5. phagocytosis: engulfing the offending substance/cell.
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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Question 4
Incorrect
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Concerning surface anatomy, where is the mitral valve found?
Your Answer: Situated in the 4th intercostal space anterior axillary line
Correct Answer: Situated in the 4th intercostal space left to the sternum
Explanation:The mitral valve is situated in the left 4th intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 5
Correct
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What are the major motor proteins that interact with microtubules?
Your Answer: Kinesin and dynein
Explanation:The major motor proteins that interact with microtubules are kinesin, which usually moves toward the (+) end of the microtubule, and dynein, which moves toward the (−) end.
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 6
Incorrect
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Regarding the anatomy of the intestine, the muscularis propria contains all of which of the following constituents?
Your Answer: Longitudinal muscle, muscularis mucosa, serosa
Correct Answer: Circular muscle, myenteric plexus, longitudinal muscle
Explanation:The muscularis mucosa/propria consists of the inner circular muscles and the outer longitudinal muscles. Between these muscles is the myenteric plexus.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 7
Incorrect
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Which one of the following cells originates from a monocyte and resembles a macrophage?
Your Answer: Oligodendrocyte
Correct Answer: Microglia
Explanation:Microglia act as the macrophages of the central nervous system, and they contribute to innate and adaptive immune responses. Studies have shown that microglial cells recognize monocyte antigens, and there are similarities between them that demonstrate that they originate from these monocytes.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 8
Correct
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A 50-year-old female is undergoing a lymph node biopsy from the posterior triangle of his neck. What structure forms the posterior boundary of the posterior triangle of the neck?
Your Answer: Trapezius muscle
Explanation:The sternocleidomastoid muscle divides the neck into anterior and posterior triangles on both sides of the neck. The posterior triangle has the following boundaries: anteriorly – sternocleidomastoid muscle posteriorly – trapezius roof – investing layer of deep cervical fascia floor – prevertebral fascia overlying splenius capitis, levator scapulae, and the scalene muscles The contents of the posterior triangle are: 1. fat 2. lymph nodes (level V) 3. accessory nerve 4. cutaneous branches of the cervical plexus – greater auricular nerve, transverse cervical nerve, lesser occipital nerve, supraclavicular nerve (A major branch of this plexus is the phrenic nerve, which arises from the anterior divisions of spinal nerves C3-C5) 5. inferior belly of omohyoid 6. branches of the thyrocervical trunk (transverse cervical and suprascapular arteries) 7. third part of the subclavian artery 8. external jugular vein
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 9
Correct
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The AV Node:
Your Answer: It decelerates impulses passing to the ventricles
Explanation:The action potentials in the sinoatrial (SA) and atrioventricular (AV) nodes are largely due to Ca2+, with no contribution by Na+ influx. The depolarization continues to conduct slowly through the atrioventricular (AV) node. The AV node is located in the right posterior portion of the interatrial septum. This is a small, bean-shaped. The atrial conductive system is organized so that the cardiac impulse does not travel from the atria into the ventricles too rapidly; this delay allows the atria to empty before ventricular contraction begins. It is the AV node and its adjacent conductive fibers that delay this transmission into the ventricles. Conduction through the AV Node is represented on the ECG by the PR interval.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 10
Incorrect
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A 35-year-old female, presents to the emergency department via ambulance. The paramedics have noted the patient's symptoms as unilateral left-sided weakness of the upper and lower limbs, homonymous hemianopia and dysphasia. She has previous personal and family history of deep vein thromboses. The report of her CT scan suggests a stroke involving the middle cerebral artery. Post recovery, she undergoes further diagnostic investigations to determine the cause of a stroke at her young age. She is eventually diagnosed with a hypercoagulable state disease called Factor V Leiden thrombophilia. An emboli in the middle cerebral artery results in dysfunction of which areas of the brain?
Your Answer: Frontal, parietal and occipital
Correct Answer: Frontal, temporal and parietal lobes
Explanation:The middle cerebral artery is a part of the circle of Willis system of anastomosis within the brain, and the most often affected by brain pathology. The primary function of the middle cerebral artery is providing oxygenated blood to related regions of the brain. It achieves this by giving off different branches to supply different brain regions, namely: The cortical branches: which supplies the primary motor and somatosensory cortical areas of some parts of the face, trunk and upper limbs. The small central branches: which supply the basal ganglia and internal capsule via the lenticulostriate vessels. The superior division: which supplies the lateral inferior frontal lobe, including the Broca area which is responsible for production of speech, language comprehension, and writing. The inferior division: which supplies the superior temporal gyrus, including Wernicke’s area which controls speech comprehension and language development.
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 11
Correct
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The sensory innervation of the oropharynx is provided by which of the following nerves:
Your Answer: Glossopharyngeal nerve
Explanation:Each subdivision of the pharynx has a different sensory innervation:the nasopharynx is innervated by the maxillary nervethe oropharynx is innervated by the glossopharyngeal nervethe laryngopharynx is innervated by the vagus nerve.
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 12
Incorrect
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A 60 year-old patient being treated for hypertension presents to the ED with swelling of the left upper limb due to poor venous return. On examination, it is found that an aneurysm of the ascending aorta is impinging on a large vein lying immediately anterosuperior to it. Which vein is it likely to be?
Your Answer: Right Internal jugular vein
Correct Answer: Left brachiocephalic
Explanation:Among the veins listed, only the left brachiocephalic vein is anterosuperior to the ascending aorta. The right brachiocephalic vein being on the right side would not be affected by the aortic aneurysm. The azygos vein lies deep in the chest on the right side. The internal thoracic vein lies interior to the anterior wall of the chest. The left superior intercostal vein is close to the aortic arch, crossing it laterally. This vein drains the 2nd to 4th interspaces on the left side. The Right internal jugular vein joins the right brachiocephalic vein which would not be affected by the aneurysm.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 13
Incorrect
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A 50-year-old man has complained of persistent hoarseness and dry cough. He has a history of smoking 20 cigarettes per day. The examination reveals no significant clinical signs of cranial nerve damage. Referred to an ENT specialist, the patient is explained how coughing is usually a defence mechanism of the body which is activated more than usual by the chemical irritants in cigarette smoke. However, the ENT doctor suspects a nerve involvement in the cough reflex as the patient also presents with hoarseness with the dry cough. Which nerves is the ENT doctor suspecting to have been affected in this patient?
Your Answer: CN X and XII
Correct Answer: CN IX and X
Explanation:Cough is an important defensive reflex that helps clear secretions and particulates from the airways. A complex reflex arc generates each cough. The cough reflex begins with irritation of the cough receptors present in the epithelium of the trachea, main carina, branching points of large airways, and more distal smaller airways. These receptors are responsive to both mechanical and chemical stimuli. Afferent pathway: Impulses from stimulated receptors are transmitted via sensory nerve fibres of the vagus nerve (mainly) and glossopharyngeal nerve and travel to the medulla diffusely. CN 5 is also thought to contribute to the afferent limb. However, the vagus is the main nerve. Central pathway: The cough centre is located in the upper brain stem and pons Efferent pathway: Impulses from the centre travel via the vagus, phrenic nerve, and spinal motor nerves to the diaphragm, abdominal wall, and muscles.
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 14
Correct
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The function of the Golgi apparatus is
Your Answer: Maturation of peptides secreted by the rER into functional proteins by glycosylation
Explanation:Steroidogenesis is a multi-step process that occurs in two organelles, the endoplasmic reticulum (ER) and the mitochondrion. The Golgi apparatus is a major collection and dispatch station of protein products received from the endoplasmic reticulum (ER). Proteins synthesized in the ER are packaged into vesicles, which then fuse with the Golgi apparatus. The majority of proteins synthesized in the rough ER undergo glycosylation which occurs in the Golgi apparatus. Glycosylation mainly refers in particular to the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules. These cargo proteins are modified and destined for secretion via exocytosis or for use in the cell. The Golgi apparatus is also involved in lipid transport and lysosome formation.
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 15
Incorrect
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The following statements concern the sensory innervation of the nasal passage:
Your Answer: the ethmoidal branch of the nasociliary nerve supplies the posterior walls of the nasal passage
Correct Answer: the infraorbital branch of the maxillary nerve supplies the vestibule
Explanation:The walls of the anterior nasal passage are supplied by the anterior ethmoidal branch of the nasociliary nerve, and the floor is innervated by the superior dental nerve (not the sphenopalatine nerves). The walls and floor of the posterior nasal passage are innervated by the long and short sphenopalatine nerves and the great palatine nerve (not the superior dental nerves and the nasociliary nerve). The vestibule is innervated by small branches of the infraorbital branch of the maxillary nerve. The nasopharynx is innervated by the sensory branches of the trigeminal nerve (not the great palatine nerve).
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 16
Incorrect
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Choose the correct statement regarding trabecular bone:
Your Answer: Is located inside the cortical bone and makes up 20% of bone in the body
Correct Answer: All of the options are correct
Explanation:Trabecular, spongy or cancellous bone. It is located inside the cortical bone and makes up around 20% of all bone in the body. It is made of spicules or plates with a high surface to volume ratio, where many cells sit on the surface of the end plates. It receives its nutrients from the extracellular fluid (ECF), exchanging about 10 mmol of calcium every 24 hours.
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This question is part of the following fields:
- Endocrinology
- Physiology
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Question 17
Incorrect
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Amongst the following cells, which is responsible for the secretion of defensins?
Your Answer: Mast cells
Correct Answer: Neutrophils
Explanation:Eosinophils are phagocytic and they are directed against helminths. Basophils are involved in allergic reactions and contain histamine and vasoactive granules in their cytoplasm. Mast cells are similar to basophils. Monocytes differentiate into macrophages in the tissue, secret interleukins and are phagocytic. Neutrophils are phagocytic but are also responsible for secreting defensins.
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This question is part of the following fields:
- Immunology
- Physiology
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Question 18
Incorrect
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Which of the following statements is true about chromosomes?
Your Answer: Diploid human cells have 46 chromosomes, 23 inherited from each parent
Correct Answer: All of the above
Explanation:All of the above mentioned statements are true regarding chromosomes.
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This question is part of the following fields:
- Genetics
- Physiology
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Question 19
Incorrect
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Which coronary artery supplies the right atria?
Your Answer: Left coronary
Correct Answer: Right coronary
Explanation:The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery arises from the left coronary artery and follows the coronary sulcus to the left. Eventually, it will fuse with the small branches of the right coronary artery. The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 20
Incorrect
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Question 21
Incorrect
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Where would one normally find venous valves?
Your Answer: Inferior vena cava
Correct Answer: Saphenous vein
Explanation:The intima of the limb veins is folded at intervals to form venous valves that prevent retrograde flow. There are no valves present in the very small veins, the great veins, or the veins in the brain and viscera.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 22
Correct
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A 33 year old woman presents with a history of recurrent infections and abscesses in the neck. Examination reveals a midline defect with an overlying scab which moves upwards on tongue protrusion. Which of the following is the most likely diagnosis?
Your Answer: Thyroglossal cyst
Explanation:Congenital neck masses are developmental anomalies typically seen in infants or children. Common conditions include thyroglossal duct cysts, branchial cleft cysts, and cystic hygromas. These malformations present as painless neck masses, which can cause dysphagia, respiratory distress, and neck pain due to compression of surrounding structures. The location of the mass depends on the embryological structure the cysts arise from. Diagnosis is made based on clinical findings and imaging results (ultrasound, CT, MRI), which also help in surgical planning. Treatment consists of complete surgical resection to prevent recurrence and complications such as infection or abscess formation. The thyroglossal cyst is present from birth and usually detected during early childhood. It presents as a painless, firm midline neck mass, usually near the hyoid bone, which elevates with swallowing and tongue protrusion. May cause dysphagia or neck/throat pain if the cyst enlarges.
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This question is part of the following fields:
- Head & Neck
- Pathology
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Question 23
Correct
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Endotoxin will typically act on which one of the following cells, to produce endogenous pyrogens?
Your Answer: Monocytes
Explanation:Endotoxin, also known as lipopolysaccharides or lipoglycans, are molecules that consist of a lipid and a polysaccharide. They bind to many cell types, but especially to monocytes, promoting the secretion of proinflammatory cytokines, acting as a pyrogen.
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This question is part of the following fields:
- Endocrinology
- Physiology
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Question 24
Incorrect
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Which of the following is NOT true of the parasympathetic control of the heart?
Your Answer: None of the above
Correct Answer: It can be blocked by beta blockers
Explanation:Parasympathetic fibers do not innervate the Beta receptors on the heart. They are innervated by the sympathetic nerve fibers. Then a beta blocker such as propranolol will block the sympathetic outflow and increase the parasympathetic tone of the heart.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 25
Correct
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Regarding the intervertebral disc, which of the following statements is CORRECT:
Your Answer: In L4 - L5 disc herniation, the L5 spinal nerve root is the most commonly affected.
Explanation:A posterolateral herniation of the disc at the L4 – L5 level would be most likely to damage the fifth lumbar nerve root, not the fourth lumbar nerve root, due to more oblique descending of the fifth lumbar nerve root within the subarachnoid space.
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 26
Incorrect
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The postextrasystolic potentiation of myocardial contractility is due to:
Your Answer: Increase in cardiac rate
Correct Answer: Increase in intracellular Ca2+
Explanation:The postextrasystolic potentiation of myocardial contractility Is not due to ventricular filling. It occurs in isolated locations in the heart and is due to increase availability of intracellular calcium.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 27
Incorrect
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Glucose absorption in the small intestine is coupled with which of the following electrolytes?
Your Answer: K
Correct Answer: Na
Explanation:Sodium-glucose linked transporter are family of proteins of different types. SGLT1 transporter is found in the intestinal mucosa of the small intestine and absorbs glucose via cotransport of Na+ ions.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 28
Incorrect
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The pressure in the sinusoids is normally:
Your Answer: Higher than hepatic artery pressure
Correct Answer: Lower than portal venous pressure
Explanation:The direction of transport of nutrients in the portal vein occurs from the portal vein to the hepatic sinusoids. Thus, he pressure of sinusoids should be lower than the pressure of he portal vein.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 29
Incorrect
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What is the result of maltase deficiency in the brush border of the small intestine?
Your Answer: Results in lack of absorption of sucrose
Correct Answer: Results in increased passage of maltose in stool
Explanation:Maltase is an enzyme produced from the surface cells of the villi, lining the small intestine and aids in hydrolysing the disaccharide maltose, which splits into two molecules of α-glucose. It is done by breaking the glycosidic bond between the ‘first’ carbon of one glucose and the ‘fourth’ carbon of the other (a 1–4 bond). Hence, a deficiency of enzyme maltase will result in the increased passage of maltose in the stool.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 30
Correct
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A 27 year old man presents with a regular tachycardia of 190 bpm. He is healthy and has no past medical history. Blood pressure and bloods are all within normal parameters however the ECG confirms a narrow complex tachycardia. The tachycardia persists after giving IV adenosine 3mg and then 6mg. What should be the next step in management of this patient?
Your Answer: IV 12mg adenosine
Explanation:For narrow complex tachycardias with no compromise then vagal manoeuvres should be trialled first. The Valsalva manoeuvre should be the first vagal manoeuvre tried and works by increasing intra-thoracic pressure and affecting baroreceptors (pressure sensors) within the arch of the aorta. It is carried out by asking the patient to hold his/her breath while trying to exhale forcibly as if straining during a bowel movement. Adenosine, an ultra-short-acting AV nodal blocking agent, is indicated if vagal manoeuvres are not effective. Adenosine may be safely used during pregnancy. After giving 3mg of adenosine with no effect, 6mg should be tried. If this fails then 12mg should be trialled. If adenosine fails then Verapamil or a beta blocker can be used as alternatives. If the patient is hemodynamically unstable or other treatments have not been effective, synchronized electrical cardioversion may be used.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
