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Question 1
Correct
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Which of the following foods do NOT contain high levels of folate?
Your Answer: Yellow vegetables
Explanation:Folate naturally occurs in a wide variety of foods, including vegetables (particularly dark green leafy vegetables), fruits and fruit juices, nuts, beans, peas, dairy products, poultry and meat, eggs, seafood, grains, and some beers. Avocado, beetroot, spinach, liver, yeast, asparagus, and Brussels sprouts are among the foods with the highest levels of folate
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This question is part of the following fields:
- Haematology
- Medicine
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Question 2
Correct
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The function of ATP in cardiac muscle contraction includes:
Your Answer: Binding to myosin after the power stroke to allow uncoupling of actin and myosin
Explanation:After calcium binds to the troponin C, there is a conformational change in the structure of troponin I and tropomyosin, which moves out of the way and frees the site where myosin can bind to actin. This results in the formation of the cross linkage of the actin and myosin giving rise to the power stroke in the contraction phase. This occurs with the release of ADP. When ATP combines to this complex it breaks and the cycle repeats itself.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 3
Correct
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Which coronary artery supplies the right atria?
Your 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
- Medicine
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Question 4
Incorrect
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Which of the following is true for P 53:
Your Answer: It binds e2f and stops the cell cycle at the g2 phase
Correct Answer: It is induced by ‘broken’ DNA
Explanation:All of the above mentioned statements are true regarding tumour suppressor genes.
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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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What happens first during depolarisation of the membrane potential?
Your Answer: Gated Na channels open allowing the influx of Na
Explanation:Generation of an action potential in response to a stimulus is a result of a previously maintained resting membrane potential (RMP). Generation of resting membrane potential is mediated mainly by potassium ions. Several membrane proteins maintain RMP by transport of ions in and out of cell. Na+/K+ ATPase pump maintains a concentration gradient of Na+ and K+ ions. Na+ concentration in extracellular fluid is higher compared to intracellular fluid and K+ ion concentration is higher intracellularly. Generation of an action potential facilitates opening of Na+ ion channels which allow for Na+ to diffuse inside the cell according to the concentration gradient.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 6
Incorrect
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Choose the standard method for comparing distributions in data sets (such as between the expected frequency of an event and the observed frequency of an event) from the list of options.
Your Answer: Mean
Correct Answer: Chi squared (X²) test
Explanation:The Chi-squared test evaluates if two variables are related. The other statistical tests mentioned do not perform this function.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 7
Incorrect
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Which of the following substances is involved in the respiratory burst by the neutrophil?
Your Answer: Superoxide dismutase forms h2o2
Correct Answer: NADPh oxidase
Explanation:The respiratory burst is a rapid release of reactive oxygen species (ROS) from neutrophils and other phagocytes. This process is crucial for the destruction of pathogens. The key components and enzymes involved in the respiratory burst include:
- NADPH oxidase: This enzyme complex plays a central role in the respiratory burst by converting oxygen (O2) into superoxide anion (O2•-), a reactive oxygen species. This is the initial step in the production of various ROS.
- Superoxide dismutase (SOD): This enzyme converts superoxide anion (O2•-) into hydrogen peroxide (H2O2). While SOD is involved in the pathway, the respiratory burst is initiated by NADPH oxidase.
- Myeloperoxidase (MPO): This enzyme uses hydrogen peroxide (H2O2) to produce hypochlorous acid (HOCl) from chloride ions (Cl-), which is a potent antimicrobial agent. Myeloperoxidase also produces other reactive species using halide ions.
- Catalase: This enzyme degrades hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). While catalase helps to protect the cell from oxidative damage by breaking down H2O2, it is not involved in the generation of ROS during the respiratory burst.
- Adenylate cyclase: This enzyme is involved in the production of cyclic AMP (cAMP) from ATP and is not directly related to the respiratory burst.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 8
Incorrect
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Question 9
Correct
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The complex twisting and folding of peptide chains describes which order of protein structure?
Your Answer: Secondary structure
Explanation:Secondary Structure refers to the coiling or folding of a polypeptide chain that gives the protein its 3-D shape. There are two types of secondary structures: the alpha (α) helix and the beta (β) pleated sheet.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 10
Correct
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Question 11
Correct
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What is the function of secondary messengers?
Your Answer: Communication from extracellular to intracellular signalling pathways
Explanation:First messengers may not physically cross the phospholipid bilayer to initiate changes within the cell directly. This functional limitation necessitates the cell to devise signal transduction mechanisms to transduce first messenger into second messengers, so that the extracellular signal may be propagated intracellularly. Second messengers are intracellular signalling molecules released by the cell to trigger physiological changes such as proliferation, differentiation, migration, survival, and apoptosis. Secondary messengers are therefore one of the initiating components of intracellular signal transduction cascades.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 12
Correct
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Question 13
Incorrect
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Transportation of proteins from the cell body to axonal terminals is known as:
Your Answer: None of the above
Correct Answer: Axoplasmic flow
Explanation:Transportation of proteins from the cell body to axonal terminals is known as axoplasmic, axonal flow or Axonal transport.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 14
Correct
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A 30-year-old female presented with upper abdominal pain. She was diagnosed with an unknown coagulopathy and has a previous history of stroke. She has been on warfarin therapy for the past 4 months. Her international normalised ratio (INR) was stabilised between 2.5 and 3.0. Noticing abnormal coagulation results, her surgeon has requested a medical consult.Her blood investigations revealed:White cell count: 13 × 109/lHaemoglobin (Hb): 11 g/dlActivated partial thromboplastin time (APTT): NormalPlatelets: 140 × 109/lINR: 6.0Pancreatic enzymes and liver function tests were normal.Other investigations:An ultrasound of the abdomen was normal.An upper GI endoscopy revealed mild gastritis. What is the most appropriate step to be taken regarding warfarin therapy?
Your Answer: Stop warfarin and observe
Explanation:The most appropriate treatment in this patient would be to stop warfarin therapy and keep the patient under observation.The drugs that lead to enhanced potency of warfarin include: disulfiram, trimethoprim-sulphamethoxazole, metronidazole, phenylbutazone, aspirin, heparin, and clofibrate. Liver disease, thrombocytopenia, hyperthyroidism also increase the oral anticoagulant potency.If the patient has minor bleeding and the international normalized ratio (INR) is >6.0, warfarin should be stopped; the INR should be rechecked daily and in addition to the stoppage of warfarin, vitamin K 2.5 mg oral or 0.5 mg intravenously should also be administered.In a patient with INR of 2.0 or 3.0, it takes two or three times longer for that individual’s blood to clot than someone who is not taking any anticoagulants. Most patients on warfarin have an INR goal of 2 to 3.If there is major bleeding then prothrombin complex concentrates 50 u/kg or fresh-frozen plasma 15 ml/kg may be considered.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 15
Correct
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Coronary flow is reduced during
Your Answer: Tachycardia
Explanation:Maximum amount of blood flow in the coronary arteries occur during diastole. When the heart rate increases which is also called tachycardia the duration of diastole decreases. Hence the amount of blood flow to the cardiac muscle also decreases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 16
Correct
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To which protein is T3 mostly bound in the serum?
Your Answer: Thyroxin-binding globulin
Explanation:In a normal person, approximately 0.03 per cent of the total serum T4, and 0.3 per cent of the total serum T3 are present in free or unbound form. The major serum thyroid hormone-binding proteins are: 1) thyroxine-binding globulin [TBG or thyropexin], 2) transthyretin [TTR or thyroxine-binding prealbumin (TBPA)], and 3) albumin (HAS, human serum albumin). TBG has highest affinity for T4, which is 50-fold higher than that of TTR and 7,000-fold higher that of HSA. As a result TBG binds 75% of serum T4, while TTR and HSA binds only 20% and Albumin 5%, respectively.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 17
Incorrect
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An 81-year-old male presented to the emergency department following a fall at home. He was diagnosed with osteoporosis about five years ago. He presently complains of significant low back pain. A lumbar spine X-ray was suggestive of a fractured lumbar vertebra. A subsequent MRI scan of the lumbosacral spine revealed a new L3 burst fracture with no evidence of cord compression. A neurosurgical consult was sought and conservative management was planned accordingly in the form of pain control, physiotherapy, and mobilization (as allowed by the pain). He also has been diagnosed with chronic renal disease (stage IV) with a creatinine clearance of 21ml/min, he was started on a Buprenorphine patch. Which of the following opioids would be safest to use for his breakthrough pain?
Your Answer: Pethidine
Correct Answer: Oxycodone
Explanation:Oxycodone is a safer opioid to use in patients with moderate to end-stage renal failure.Active metabolites of morphine accumulate in renal failure which means that long-term use is contraindicated in patients with moderate/severe renal failure. These toxic metabolites can accumulate causing toxicity and risk overdose. Oxycodone is mainly metabolised in the liver and thus safer to use in patients with moderate to end-stage renal failure with dose reductions.Adverse effects:Constipation is the most common overall side effect. Others include: asthenia, dizziness, dry mouth, headache, nausea, pruritus, etc. Medications in renal failure:Drugs to be avoided in patients with renal failureAntibiotics: tetracycline, nitrofurantoinNSAIDsLithiumMetforminDrugs that require dose adjustment:Most antibiotics including penicillin, cephalosporins, vancomycin, gentamicin, streptomycinDigoxin, atenololMethotrexateSulphonylureasFurosemideOpioidsRelatively safe drugs:Antibiotics: erythromycin, rifampicinDiazepamWarfarin
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 18
Incorrect
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The complete oxidation of 1 molecule of glucose to CO2 and H20 produces a total of __ATP.
Your Answer: 28
Correct Answer: 38
Explanation:Textbooks often state that 38 ATP molecules can be made per oxidised glucose molecule during cellular respiration (2 from glycolysis, 2 from the Krebs cycle, and about 34 from the electron transport system). However, this maximum yield is never quite reached because of losses due to leaky membranes as well as the cost of moving pyruvate and ADP into the mitochondrial matrix, and current estimates range around 29 to 30 ATP per glucose.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 19
Correct
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Which of the following happens when anterograde neurons are stimulated?
Your Answer: Smooth muscle relaxation ahead of the stimulus
Explanation:Nitric oxide is thought to act as an anterograde neurotransmitter. Nitric oxide causes relaxation of smooth muscles ahead of the stimulus. Clinically it is used as a potent vasodilator.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 20
Incorrect
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Physiological effects of T3 on the heart include all the following except:
Your Answer: Increased proportion of α-myosin heavy chain in the atria
Correct Answer: Increased expression of β-myosin heavy chain gene
Explanation:Tri-iodothyronine, also known as T3, is a hormone which can affect almost every system in the human body. In the heart, it increases the number of β1-adrenergic receptors, enhances the response to circulating catecholamines, increases the proportion of α-myosin heavy chains in the atria, and increases the expression of serca pump gene.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 21
Correct
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Which of the following is not true regarding mitochondrial chromosome disorders?
Your 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 22
Correct
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Salty taste is triggered by:
Your Answer: Amiloride-sensitive sodium channel
Explanation:Amiloride-sensitive sodium channels also known as epithelial Na channels is a membrane bound ion channel that is selectively permeable to Na+ ions. These channels are located throughout different epithelial membranes in the body. It is found in taste receptor cells, where it plays an important role in salt taste perception. They are also located in the kidney, the lung and the colon. Hyperpolarization-activated, cyclic nucleotide-gated (HCN) voltage-gated ion channels are widely seen in the cortex, hippocampus, thalamus and brain regions that underlie the generation of both focal and generalized-onset seizures. The metabotropic glutamate receptor (mGluRs) perform a variety of functions in the central and peripheral nervous systems. They are involved in learning, memory, anxiety, and the perception of pain. Gustducin is a G protein associated with taste and gustatory system. It plays a major role in sensation of bitter, sweet and umami stimuli.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 23
Correct
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During exercise, a man consumes 2L O2/min, his arterial 02 content is 190 ml/l and the 02 content of his mixed venous blood is 130ml/l. His cardiac output is approximately:
Your Answer: 33l/min
Explanation:In Fick’s original method, the following variables are measured:VO2, oxygen consumption in ml of pure gaseous oxygen per minute. This may be measured using a spirometer within a closed rebreathing circuit incorporating a CO2 absorberCa, the oxygen concentration of blood taken from the pulmonary vein (representing oxygenated blood)Cv, the oxygen concentration of blood from an intravenous cannula (representing deoxygenated blood)From these values, we know that:VO2 = (CO x Ca) – (CO x Cv)where CO = Cardiac Output, Ca = Oxygen concentration of arterial blood and Cv = Oxygen concentration of mixed venous blood.This allows us to sayCO = VO2/{Ca – Cv}and hence calculate cardiac output.Therefore CO = 2/(0.190-0.130) = 33l/minNote that (Ca – Cv) is also known as the arteriovenous oxygen difference.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 24
Correct
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How does pregnancy affect the cardiac output of a patient?
Your Answer: Increased cardiac output due to increase in heart rate and stroke volume
Explanation:Cardiac Output increases to a similar degree as the blood volume. During the first trimester cardiac output is 30-40% higher than in the non-pregnant state. Steady rises are shown on Doppler echocardiography, from an average of 6.7 litres/minute at 8-11 weeks to about 8.7 litres/minute flow at 36-39 weeks; they are due, primarily, to an increase in stroke volume (35%) and, to a lesser extent, to a more rapid heart rate (15%). There is a steady reduction in systemic vascular resistance (SVR) which contributes towards the hyperdynamic circulation observed in pregnancy
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 25
Correct
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Inactive cellular marrow is called
Your Answer: Yellow marrow
Explanation:The two types of bone marrow are red marrow, which consists mainly of hematopoietic tissue, and yellow marrow, which is mainly made up of fat cells.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 26
Incorrect
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What is the structure of nucleosomes?
Your Answer: Strands of double strand DNA + introns
Correct Answer: Strands of double strand DNA + histones
Explanation:DNA is packed and condensed by binding to histone proteins. The double stranded DNA forms a complex with histone proteins which is called a nucleosome. There are 8 histone proteins contained in one core of nucleosome.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 27
Correct
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In the normal adult, haematopoiesis is present
Your Answer: Axial skeleton and proximal ends of long bones
Explanation:In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 28
Incorrect
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The nucleus ambiguus:
Your Answer: All of the above
Correct Answer: Regulates swallowing, phonation and parasympathetic supply to the heart via CN IX, X and XI
Explanation:Nucleus Ambiguus is a group of large motor neurons found deep in the medullary reticular formation. It contains cell bodies of nerves that are responsible for the innervation of muscles of speech and swallowing which are located in the soft palate, pharynx and larynx. Additionally, it contains cholinergic preganglionic parasympathetic neurons of the heart via CN X, IX and XI
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This question is part of the following fields:
- Medicine
- Neurology
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Question 29
Incorrect
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Impulse conduction through the AV node is slow and depends on the action potential produced by which of the following.
Your Answer: Potassium flux
Correct Answer: Calcium flux
Explanation:The action potentials in the SA and AV nodes are largely due to Ca2+, with no contribution by Na+ influx.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 30
Correct
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The TSH receptor produces its effects in the thyrocyte via:
Your Answer: G-protein coupled activation of adenylyl cyclise and phospholipase c
Explanation:The thyrotropin receptor, also known as TSH receptor, responds to the thyroid stimulating hormone or thyrotropin to stimulate production of T3 and T4. It is a G protein-coupled receptor which leads to stimulation of phospholipase C and adenylyl cyclase, mediated by Gq/11 and Gs.
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This question is part of the following fields:
- Endocrinology
- Medicine
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SESSION STATS - PERFORMANCE PER SPECIALTY
