Autonomic Nervous System (ANS) Pharmacology MCQs
1. Which receptor subtype is primarily responsible for increasing aqueous humor outflow through contraction of the ciliary muscle?
A. α₁ receptor
B. β₂ receptor
C. M₃ receptor
D. Nn receptor
2. A patient receiving phenoxybenzamine develops reflex tachycardia mainly due to:
A. Blockade of β₁ receptors
B. Blockade of presynaptic α₂ receptors
C. Stimulation of M₂ receptors
D. Activation of nicotinic receptors
3. Which autonomic neurotransmitter is released by postganglionic sympathetic fibers supplying eccrine sweat glands?
A. Norepinephrine
B. Dopamine
C. Acetylcholine
D. Epinephrine
4. The vasomotor reversal of Dale occurs when epinephrine is administered after:
A. Atropine
B. Propranolol
C. Phenoxybenzamine
D. Neostigmine
5. Which drug selectively stimulates dopamine D₁ receptors causing renal vasodilation at low doses?
A. Dobutamine
B. Dopamine
C. Isoproterenol
D. Phenylephrine
6. A patient with organophosphate poisoning is expected to exhibit all EXCEPT:
A. Miosis
B. Bronchoconstriction
C. Tachycardia due to β₁ stimulation
D. Increased salivation
7. Which receptor is predominantly responsible for relaxation of the detrusor muscle of the urinary bladder?
A. α₁
B. β₃
C. M₂
D. Nn
8. Tyramine-induced hypertensive crisis is most likely in a patient taking:
A. Propranolol
B. Atropine
C. Selegiline
D. Non-selective MAO inhibitor
9. Which of the following drugs is a reversible cholinesterase inhibitor capable of crossing the blood-brain barrier?
A. Edrophonium
B. Neostigmine
C. Pyridostigmine
D. Physostigmine
10. The ganglionic nicotinic receptor is classified as:
A. Ligand-gated ion channel
B. G-protein coupled receptor
C. Enzyme-linked receptor
D. Nuclear receptor
11. Which sympathomimetic drug releases stored norepinephrine from adrenergic nerve terminals?
A. Phenylephrine
B. Clonidine
C. Amphetamine
D. Dobutamine
12. A patient receiving timolol eye drops for glaucoma may experience:
A. Mydriasis
B. Bronchodilation
C. Bradycardia
D. Increased aqueous humor production
13. Which adrenergic receptor subtype is coupled to Gq protein and increases intracellular calcium?
A. β₁
B. β₂
C. α₁
D. α₂
14. Pralidoxime is most effective when administered:
A. Before aging of phosphorylated enzyme occurs
B. After atropine administration only
C. In chronic lead poisoning
D. During myasthenia gravis crisis
15. Which drug is preferred for diagnosis of pheochromocytoma due to its short-acting α-blocking action?
A. Prazosin
B. Phentolamine
C. Tamsulosin
D. Terazosin
16. The receptor responsible for increased heart rate and force of contraction is:
A. α₂
B. β₁
C. β₂
D. M₂
17. Pilocarpine is contraindicated in patients with:
A. Xerostomia
B. Open-angle glaucoma
C. Bronchial asthma
D. Neurogenic bladder
18. Which autonomic drug is capable of producing “chemical sympathectomy”?
A. Guanethidine
B. Clonidine
C. Phenylephrine
D. Isoproterenol
19. The major mechanism of action of clonidine is:
A. Peripheral α₁ stimulation
B. Central α₂ receptor agonism
C. β₁ blockade
D. Muscarinic receptor blockade
20. Which of the following drugs is most likely to precipitate acute angle-closure glaucoma?
A. Bethanechol
B. Pilocarpine
C. Atropine
D. Carbachol
1-C, 2-B, 3-C, 4-C, 5-B, 6-C, 7-B, 8-D, 9-D, 10-A, 11-C, 12-C, 13-C, 14-A, 15-B, 16-B, 17-C, 18-A, 19-B, 20-C
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