Anatomy and Physiology Mini MCQs Answers 2023/24

Anatomy and Physiology Mini MCQs Answers 2023/24 1. (17.) Which one of the following events is most likely to happen after M2 receptor stimulation? (A) Hyperpolarization of the cell membrane (B) Closure of K+ channels (C) Increased free cAMP levels (D) Direct opening of ligand gated Na+ channels (E) IP3 and DAG production Answer: A. M2 receptor stimulation leads to Gi protein activation, which results in decrease in cAMP. It also results in opening of K+ and hyperpolarization. M2 receptor activation doesn’t cause change in IP3 and DAG or Na+ flux. 2. (24.) The production of cyclic guanosine monophosphate (cGMP) is associated with the postsynaptic effect of… (A) Acetylcholine (ACh) (B) Epinephrine (C) γ-aminobutryric acid (GABA) (D) Glutamate (E) Nitric oxide Answer: E. NO acts as a paracrine agent and as neurotransmitter. It stimulates the action of guanylate cyclase which, in turn, promotes the formation of cyclic guanosine monophosphate (cGMP). The physiologic effects of NO are produced by cGMP-dependent kinases that phosphorylate a variety of intracellular proteins. In the gastrointestinal system, NO facilitates smooth muscle relaxation, and in the cardiovascular system, it relaxes blood vessels. 3. (27.) Which of the following pairs are correct regarding receptor stimulation and effect? (A) β1 / uterine relaxation (β2) (B) M2 / salivation (M3) (C) α1 / accommodation of near vision (M3) (D) M3 / gastric secretion increase (E) α1 / smooth muscle contraction (F) β1 / renin release from kidney (G) α1 / erection (M3/NO) (H) M2 / GIT smooth muscle relaxation (β2) (I) α1 / detrusor muscle contraction (M3) (J) β2 / bronchodilation (K) β3 / increased lipolysis (L) M3 / mydriasis (α1) (M) α1 / inhibition of insulin secretion from Islets (α2) (N) M3 / bladder trigone (internal sphincter) contraction (α1) (O) β1 / positive chronotropic effect on the heart (P) α2 / feedback inhibition of NE Answer: D, E, F, J, K, O, and P. 4. (30.) Which of the following responses is mediated by parasympathetic muscarinic receptors? (A) Dilation of bronchiolar smooth muscle (B) Erection (C) Ejaculation (D) Constriction of GI sphincters (E) Increased cardiac contractility Answer: B. Erection is a parasympathetic muscarinic response. All others listed are sympathetic responses. 5. (31.) Which one of the following effects is not caused by the drinking of soda that contains bethanechol? (A) Bradycardia (B) Bronchospasm (C) Diarrhea (E) Lacrimation Answer: D. Bethanechol stimulates M receptors and thus causes parasympathetic effects (SLUDGE, salivation, lacrimation, urination, defecation, GI upset, emesis).It may causes the release of NO and hypotension. 6. (35.) During your time studying medicine at Grenada you decide to take a course in scuba diving. Unfortunately you are susceptible to sea-sickness so you take scopolamine (acts in a similar manner to atropine) to try and prevent this. As you board the boat you begin to feel heart palpitations, this would most likely be due to: (A) Stimulation of beta receptors (B) Stimulation of alpha receptors (C) Stimulation of muscarinic receptors (D) Inhibition of beta receptors Answer: (A or) E. if the palpitations comes from the medication, choice E is the answer. If it is coming from your excitement, choice A is the answer. 7. (36.) Urination in the human subject is decreased by... (A) Acetylcholine (B) Atropine (C) Edrophonium (D) Nicotine (E) Neostigmine Answer: B. Urinary retention is a well known adverse effect of drugs that have antagonist effects on muscarinic receptors. 8. (43.) The concept of “autonomic tone” is quite advantageous because it allows the nervous system to have much finer control over the function of an organ or organ system. This is exemplified in the control of systemic arterioles. Which of the following actions would lead to vasodilation of systemic arterioles? (A) Increased activity of preganglionic parasympathetic neurons (B) Decreased activity of postganglionic parasympathetic neurons (C) Increased activity of postganglionic sympathetic neurons (D) Decreased activity of postganglionic sympathetic neurons (E) Increased activity of preganglionic sympathetic neurons Answer: D. Decreased activity of postganglionic sympathetic neurons leads to vasodilation of systemic arterioles. In contrast, increased activity in postganglionic sympathetics results in vasoconstriction. 9. (44.) A patient is prescribed a drug that caused dizziness on standing and a stuffy nose. The dizziness only occurred when he started the drug. Most likely drug is? (A) Albuterol (B) Prazosin (C) Phenylephrine (D) Propranolol (E) Methylphenidate Answer: B. Prazosin is a α1 antagonist. α1 stimulation helps nasal congestion, and increase peripheral resistance and thus blood pressure. By blocking this receptor, Prazosin can lower the blood pressure with possible significant postural hypotension. It also used to treat benign prostatic hypertrophy. 10. (46.) Following a myocardial infarct, a 40-year-old male patient is being treated prophylactically with propranolol. In terms of adverse effects of the drug, which of the following is most likely to occur with use of this specific β blocker? (A) Bradycardia, mydriasis, and sweating (B) Bronchoconstriction, hyperglycemia, and hypotension (C) Hypoglycemia, hyperlipidemia, and sedation (D) Micturition, and mydriasis (E) Migraine headaches and AV block Answer: C. Propranolol is a nonselective β blocker and can cause bradycardia, bronchoconstriction, hypotension, and AV block. The drug also causes hypoglycemia and CNS effects, including sedation. The chronic use of propranolol is associated with changes in plasma lipids, including elevations in both LDL cholesterol and triglycerides. Mydriasis is associated with blockade of M receptors, and both micturition and sweating result from activation of such receptors. Propranolol is used to treat migraine. 11. (47.) A drug is prescribed to a type I diabetic. The drug was for a cardiovascular disorder. 3 days later the patient was comatose and hypoglycemic and brought to ER. Following glucose infusion he recovered but was surprised since he always knew the signs of a hypoglycemic event and was careful to avoid them by drinking eating frequently. What was the likely drug? (A) Phenylephrine (B) Propranolol (C) Phenelzine (D) Albuterol (E) Phentolamine Answer: B. Hypoglycemia triggers sympathetic activity which would promote glycogenolysis and increased blood glucose. The increased sympathetic activity also increases heart rate, anxiety, sweating and tremor. A β blocker masks the symptoms and signs of hypoglycemia and prevents the diabetic from realizing that his blood glucose is becoming dangerously low. . . . . . . . . .