Q.1 Which of the following neurotransmitters is primarily released by postganglionic sympathetic neurons?
Acetylcholine
Dopamine
Norepinephrine
Serotonin
Explanation - Most postganglionic sympathetic neurons release norepinephrine, except those innervating sweat glands, which release acetylcholine.
Correct answer is: Norepinephrine
Q.2 Which receptor type is primarily responsible for mediating bronchial smooth muscle relaxation?
Alpha-1
Beta-1
Beta-2
Muscarinic M3
Explanation - Beta-2 adrenergic receptors are abundant in bronchial smooth muscle and cause relaxation when stimulated.
Correct answer is: Beta-2
Q.3 Pilocarpine is an agonist for which type of receptor?
Muscarinic
Nicotinic
Alpha-1
Beta-2
Explanation - Pilocarpine is a muscarinic agonist that stimulates parasympathetic activity, used in glaucoma treatment.
Correct answer is: Muscarinic
Q.4 Which enzyme is responsible for the breakdown of acetylcholine in the synaptic cleft?
Monoamine oxidase
Acetylcholinesterase
Catechol-O-methyltransferase
Choline acetyltransferase
Explanation - Acetylcholinesterase rapidly hydrolyzes acetylcholine into choline and acetate to terminate neurotransmission.
Correct answer is: Acetylcholinesterase
Q.5 Phenylephrine is classified as which type of drug?
Beta-1 agonist
Alpha-1 agonist
Muscarinic antagonist
Beta-2 agonist
Explanation - Phenylephrine selectively stimulates alpha-1 receptors, causing vasoconstriction and increasing blood pressure.
Correct answer is: Alpha-1 agonist
Q.6 Atropine blocks which type of receptor?
Nicotinic
Muscarinic
Alpha-1
Beta-2
Explanation - Atropine is a competitive antagonist at muscarinic acetylcholine receptors, leading to decreased parasympathetic effects.
Correct answer is: Muscarinic
Q.7 Which of the following drugs is a non-selective beta blocker?
Propranolol
Metoprolol
Atenolol
Prazosin
Explanation - Propranolol blocks both beta-1 and beta-2 adrenergic receptors, reducing heart rate and bronchial dilation.
Correct answer is: Propranolol
Q.8 Clonidine primarily acts on which type of receptor?
Alpha-1
Alpha-2
Beta-1
Muscarinic M2
Explanation - Clonidine is an alpha-2 adrenergic agonist that reduces sympathetic outflow from the CNS, lowering blood pressure.
Correct answer is: Alpha-2
Q.9 Which parasympathomimetic drug is commonly used in glaucoma treatment?
Pilocarpine
Atropine
Propranolol
Phenylephrine
Explanation - Pilocarpine stimulates muscarinic receptors in the eye, increasing aqueous humor outflow and reducing intraocular pressure.
Correct answer is: Pilocarpine
Q.10 Botulinum toxin causes muscle paralysis by:
Blocking nicotinic receptors
Inhibiting acetylcholine release
Stimulating muscarinic receptors
Activating beta-2 receptors
Explanation - Botulinum toxin prevents acetylcholine release at neuromuscular junctions, causing flaccid paralysis.
Correct answer is: Inhibiting acetylcholine release
Q.11 Which receptor is primarily responsible for increasing heart rate when stimulated?
Alpha-1
Beta-1
Beta-2
Muscarinic M3
Explanation - Beta-1 adrenergic receptors in the heart increase heart rate and contractility upon stimulation.
Correct answer is: Beta-1
Q.12 Neostigmine is used clinically because it:
Blocks muscarinic receptors
Inhibits acetylcholinesterase
Activates alpha-1 receptors
Blocks beta receptors
Explanation - Neostigmine increases acetylcholine levels at synapses by inhibiting its breakdown, improving muscle contraction in myasthenia gravis.
Correct answer is: Inhibits acetylcholinesterase
Q.13 Tropicamide is an antagonist at which receptor type?
Muscarinic
Nicotinic
Alpha-1
Beta-2
Explanation - Tropicamide blocks muscarinic receptors in the eye, causing pupil dilation for ophthalmic examinations.
Correct answer is: Muscarinic
Q.14 Which of the following is a selective alpha-1 adrenergic blocker?
Prazosin
Clonidine
Propranolol
Phenylephrine
Explanation - Prazosin selectively blocks alpha-1 receptors, causing vasodilation and lowering blood pressure.
Correct answer is: Prazosin
Q.15 Which neurotransmitter acts on nicotinic receptors in the autonomic ganglia?
Acetylcholine
Norepinephrine
Epinephrine
Dopamine
Explanation - Acetylcholine released by preganglionic neurons stimulates nicotinic receptors on postganglionic neurons.
Correct answer is: Acetylcholine
Q.16 Epinephrine has a greater effect on which receptor type at low doses?
Alpha-1
Beta-1
Beta-2
Muscarinic
Explanation - At low doses, epinephrine preferentially stimulates beta-2 receptors, causing vasodilation in skeletal muscle.
Correct answer is: Beta-2
Q.17 Hexamethonium is an example of a drug that:
Blocks muscarinic receptors
Blocks nicotinic receptors in autonomic ganglia
Stimulates beta receptors
Inhibits acetylcholinesterase
Explanation - Hexamethonium is a ganglionic blocker that inhibits transmission in both sympathetic and parasympathetic ganglia.
Correct answer is: Blocks nicotinic receptors in autonomic ganglia
Q.18 Which of the following is a muscarinic antagonist used to treat bradycardia?
Atropine
Neostigmine
Propranolol
Phenylephrine
Explanation - Atropine blocks parasympathetic activity on the heart, increasing heart rate in bradycardia.
Correct answer is: Atropine
Q.19 Dobutamine primarily acts on which receptor to increase cardiac output?
Alpha-1
Beta-1
Beta-2
Muscarinic M2
Explanation - Dobutamine is a selective beta-1 agonist, enhancing heart contractility and cardiac output.
Correct answer is: Beta-1
Q.20 Which drug is used as a reversal agent for non-depolarizing neuromuscular blockers?
Atropine
Neostigmine
Epinephrine
Clonidine
Explanation - Neostigmine increases acetylcholine at the neuromuscular junction to overcome competitive blockade.
Correct answer is: Neostigmine
Q.21 Miosis (pupil constriction) is mediated by stimulation of which receptor?
Alpha-1
Beta-2
Muscarinic M3
Nicotinic
Explanation - Muscarinic M3 receptors on the iris sphincter muscle mediate pupil constriction.
Correct answer is: Muscarinic M3
Q.22 Which adrenergic receptor is primarily responsible for vasoconstriction in most blood vessels?
Alpha-1
Beta-1
Beta-2
Muscarinic M2
Explanation - Alpha-1 receptors in vascular smooth muscle mediate vasoconstriction when stimulated.
Correct answer is: Alpha-1
Q.23 Which drug is a reversible acetylcholinesterase inhibitor used to treat myasthenia gravis?
Neostigmine
Atropine
Hexamethonium
Phenylephrine
Explanation - Neostigmine inhibits acetylcholinesterase reversibly, enhancing cholinergic transmission in skeletal muscle.
Correct answer is: Neostigmine
Q.24 Which of the following is an alpha-2 agonist that reduces sympathetic outflow?
Clonidine
Prazosin
Phenylephrine
Propranolol
Explanation - Clonidine stimulates central alpha-2 receptors, decreasing sympathetic nerve activity and lowering blood pressure.
Correct answer is: Clonidine
Q.25 Which receptor is targeted by anticholinergic drugs to reduce gastric secretions?
Muscarinic
Nicotinic
Beta-1
Alpha-1
Explanation - Anticholinergics block muscarinic receptors in the stomach, decreasing acid secretion.
Correct answer is: Muscarinic