The Distribution of Cholinergic Receptors MCQs With Answer provides B. Pharm students a focused, exam-oriented review of where cholinergic receptors are located and how location determines function and drug response. This concise introduction highlights muscarinic (M1–M5) and nicotinic (Nm, Nn, α-subtypes) receptor distribution across the CNS, autonomic ganglia, neuromuscular junction, glands, heart, vasculature and visceral organs. Emphasis is placed on receptor coupling (Gq/Gi/ion channels), clinical correlations (glaucoma, myasthenia gravis, overactive bladder), and pharmacologic targets (agonists, antagonists, cholinesterase inhibitors). Ideal for revision, these MCQs reinforce pattern recognition of receptor sites and therapeutic implications. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which site is classically rich in M1 muscarinic receptors?
- Cerebral cortex and hippocampus
- SA node of the heart
- Neuromuscular junction of skeletal muscle
- Vascular smooth muscle
Correct Answer: Cerebral cortex and hippocampus
Q2. M2 muscarinic receptors are predominantly located at which cardiac site?
- SA and AV nodes
- Atrial endothelial cells
- Cardiac pacemaker-independent Purkinje fibers only
- Coronary smooth muscle cells
Correct Answer: SA and AV nodes
Q3. Which muscarinic subtype primarily mediates smooth muscle contraction and glandular secretion?
- M3
- M2
- M4
- M5
Correct Answer: M3
Q4. Where are neuronal nicotinic (Nn) receptors abundantly found?
- Autonomic ganglia and central nervous system
- Neuromuscular junction of skeletal muscle
- Cardiac myocytes
- Gastric parietal cells only
Correct Answer: Autonomic ganglia and central nervous system
Q5. The Nm (muscle-type nicotinic) receptors are localized primarily at:
- Neuromuscular junction of skeletal muscle
- Autonomic ganglia
- Pons and medulla nuclei
- Sweat gland ducts
Correct Answer: Neuromuscular junction of skeletal muscle
Q6. Which receptor subtype mediates bronchial smooth muscle contraction in response to acetylcholine?
- M3 muscarinic receptors
- Nicotinic receptors at ganglia
- M2 muscarinic receptors
- Beta-2 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q7. Which muscarinic receptor subtype accounts for the negative chronotropic effect of acetylcholine on the heart?
- M2
- M1
- M3
- M5
Correct Answer: M2
Q8. Cholinergic stimulation of the adrenal medulla acts on which receptor type?
- Neuronal nicotinic (Nn) receptors
- Muscarinic M3 receptors
- Muscarinic M2 receptors
- Muscarinic M1 receptors
Correct Answer: Neuronal nicotinic (Nn) receptors
Q9. Eccrine sweat glands are innervated by sympathetic cholinergic fibers acting at which receptor?
- M3 muscarinic receptors
- Nicotinic muscle (Nm) receptors
- M2 muscarinic receptors
- Alpha-1 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q10. Endothelial muscarinic receptors that cause NO-mediated vasodilation are primarily which subtype?
- M3
- M1
- Nicotinic Nn
- M4
Correct Answer: M3
Q11. Which muscarinic subtypes are coupled to Gq proteins activating phospholipase C (PLC)?
- M1, M3, M5
- M2, M4
- Only M2
- Only nicotinic receptors
Correct Answer: M1, M3, M5
Q12. Which muscarinic receptor subtype is mainly coupled to Gi proteins inhibiting adenylate cyclase?
- M2
- M3
- M1
- M5
Correct Answer: M2
Q13. Which cholinergic receptors are ionotropic ligand-gated cation channels?
- Nicotinic receptors
- Muscarinic M1 receptors
- Muscarinic M2 receptors
- M3 muscarinic receptors
Correct Answer: Nicotinic receptors
Q14. Atropine produces its clinical effects by blocking which receptor class?
- Muscarinic receptors
- Nicotinic receptors
- Beta adrenergic receptors
- Alpha adrenergic receptors
Correct Answer: Muscarinic receptors
Q15. Pilocarpine, used in glaucoma, acts primarily at which receptor subtype?
- M3 muscarinic receptors
- M2 muscarinic receptors
- Nicotinic muscle receptors
- Alpha-1 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q16. Succinylcholine causes depolarizing blockade at which receptor?
- Nm (neuromuscular nicotinic) receptors
- Nn ganglionic nicotinic receptors
- M2 muscarinic receptors
- M3 muscarinic receptors
Correct Answer: Nm (neuromuscular nicotinic) receptors
Q17. Which drug acts as a ganglionic blocker by antagonizing Nn receptors?
- Trimethaphan
- Pilocarpine
- Bethanechol
- Neostigmine
Correct Answer: Trimethaphan
Q18. Which muscarinic subtype is highly expressed in the hippocampus and linked to learning and memory?
- M1
- M2
- M3
- M4
Correct Answer: M1
Q19. Activation of nicotinic receptors at autonomic ganglia mainly increases permeability to which ions?
- Sodium and potassium
- Chloride only
- Calcium only
- Magnesium only
Correct Answer: Sodium and potassium
Q20. Tubocurarine blocks transmission at the neuromuscular junction by antagonizing which receptor?
- Nm nicotinic receptors
- M3 muscarinic receptors
- Nn ganglionic receptors
- M2 muscarinic receptors
Correct Answer: Nm nicotinic receptors
Q21. Which muscarinic receptor subtype is predominantly expressed in striatum and implicated in motor control?
- M4
- M3
- M1
- M5
Correct Answer: M4
Q22. Which muscarinic subtype is most associated with stimulation of gastric acid secretion?
- M1
- M2
- M3
- M4
Correct Answer: M1
Q23. Salivary gland secretion is primarily mediated by which receptor subtype?
- M3 muscarinic receptors
- Nicotinic receptors
- M2 muscarinic receptors
- Beta-2 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q24. Miosis (pupil constriction) is produced by activation of which receptor in the iris sphincter?
- M3 muscarinic receptors
- M2 muscarinic receptors
- Nicotinic receptors
- Beta-adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q25. M5 muscarinic receptors are relatively restricted and implicated in regulation of:
- Cerebral blood flow and midbrain dopaminergic function
- Cardiac contractility
- Renal sodium reabsorption
- Neuromuscular transmission
Correct Answer: Cerebral blood flow and midbrain dopaminergic function
Q26. Nicotinic cholinergic receptors are NOT normally found on which cell type?
- Ventricular cardiac myocytes
- Autonomic ganglion cells
- Adrenal chromaffin cells
- Neuromuscular junctional muscle membrane
Correct Answer: Ventricular cardiac myocytes
Q27. Acetylcholine-induced vasodilation in intact vessels is mediated indirectly by:
- Endothelial M3 receptors releasing nitric oxide
- Direct activation of vascular smooth muscle M2
- Ganglionic nicotinic receptors
- Beta-2 adrenergic receptors
Correct Answer: Endothelial M3 receptors releasing nitric oxide
Q28. Which drug is a selective M3 antagonist used to treat overactive bladder?
- Darifenacin
- Atropine
- Pilocarpine
- Neostigmine
Correct Answer: Darifenacin
Q29. Which receptor subtype is a major therapeutic target for improving cognition in Alzheimer’s disease?
- M1 muscarinic receptors (and certain nicotinic subtypes)
- Nm nicotinic receptors at NMJ
- M3 muscarinic receptors in salivary glands
- Alpha-1 adrenergic receptors
Correct Answer: M1 muscarinic receptors (and certain nicotinic subtypes)
Q30. Which muscarinic receptor predominates in the urinary bladder detrusor muscle to cause contraction?
- M3
- M2
- M1
- M4
Correct Answer: M3
Q31. Which neuronal nicotinic subunit is commonly abundant in the hippocampus and implicated in synaptic plasticity?
- α7 nicotinic subunit
- β1 nicotinic subunit
- α1 nicotinic subunit
- γ nicotinic subunit
Correct Answer: α7 nicotinic subunit
Q32. Persistent activation of Nm receptors by succinylcholine causes which phenomenon at the NMJ?
- Depolarizing block (desensitization)
- Immediate non-depolarizing blockade
- Increased acetylcholinesterase activity
- Selective M2 activation
Correct Answer: Depolarizing block (desensitization)
Q33. Which receptor type mediates fast synaptic transmission in autonomic ganglia?
- Nicotinic Nn receptors
- M3 muscarinic receptors
- M2 muscarinic receptors
- Beta-1 adrenergic receptors
Correct Answer: Nicotinic Nn receptors
Q34. A muscarinic agonist would be expected to produce which combination of effects?
- Bradycardia, bronchoconstriction, increased salivation
- Tachycardia, bronchodilation, dry mouth
- Hypertension, mydriasis, decreased gut motility
- Skeletal muscle paralysis only
Correct Answer: Bradycardia, bronchoconstriction, increased salivation
Q35. Presynaptic muscarinic autoreceptors that inhibit ACh release are primarily which subtype?
- M2
- M1
- M3
- M5
Correct Answer: M2
Q36. Which muscarinic receptor subtype is commonly found on presynaptic terminals modulating neurotransmitter release?
- M2
- M3
- M1
- M5
Correct Answer: M2
Q37. Which compound is a ganglionic stimulant that activates Nn receptors?
- Nicotine
- Atropine
- Pilocarpine
- Neostigmine
Correct Answer: Nicotine
Q38. Which receptor type is the principal mediator of skeletal muscle contraction at the motor endplate?
- Nm nicotinic receptors
- M3 muscarinic receptors
- Nn nicotinic receptors in ganglia
- M2 muscarinic receptors
Correct Answer: Nm nicotinic receptors
Q39. Reversible acetylcholinesterase inhibitors such as neostigmine improve neuromuscular transmission by increasing acetylcholine at which receptors?
- Nm receptors at the neuromuscular junction
- M3 receptors in glands only
- M2 receptors in heart only
- Alpha-1 adrenergic receptors
Correct Answer: Nm receptors at the neuromuscular junction
Q40. Which muscarinic receptor subtype is highly expressed in the striatum and modulates dopaminergic signaling?
- M4
- M2
- M3
- M1
Correct Answer: M4
Q41. Which receptor subtype is prominently expressed in enteric neurons controlling gastrointestinal motility?
- M3 muscarinic receptors (and M1 in neuronal circuits)
- Nm nicotinic receptors only
- M5 exclusively
- M4 only
Correct Answer: M3 muscarinic receptors (and M1 in neuronal circuits)
Q42. Parasympathetic stimulation of pancreatic beta cells that enhances insulin release primarily involves which receptor?
- M3 muscarinic receptors
- M2 muscarinic receptors
- Nicotinic Nn receptors
- Beta-2 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q43. Accommodation (near vision) mediated by contraction of the ciliary muscle depends on which receptor subtype?
- M3 muscarinic receptors
- M2 muscarinic receptors
- Nicotinic receptors
- Alpha-1 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q44. The fast excitatory postsynaptic potentials in autonomic ganglia are produced by which receptor class?
- Nicotinic ganglionic (Nn) receptors
- M3 muscarinic receptors
- M4 presynaptic receptors
- Beta-1 adrenergic receptors
Correct Answer: Nicotinic ganglionic (Nn) receptors
Q45. Loss of which cholinergic receptor subtype has been repeatedly observed in Alzheimer’s disease brain studies?
- α4β2 nicotinic receptors
- Nm nicotinic receptors at NMJ
- M3 muscarinic receptors in salivary glands
- M5 muscarinic receptors only
Correct Answer: α4β2 nicotinic receptors
Q46. Which muscarinic receptor subtype has been linked to modulation of midbrain dopaminergic neurons and implicated in drug reward pathways?
- M5
- M2
- M1
- M3
Correct Answer: M5
Q47. Human eccrine sweat gland response to cholinergic stimulation is mediated by which receptor and explains antimuscarinic side effects?
- M3 muscarinic receptors
- Nicotinic receptors at ganglia
- M2 muscarinic receptors
- Alpha-1 adrenergic receptors
Correct Answer: M3 muscarinic receptors
Q48. Botulinum toxin impairs cholinergic transmission by which mechanism affecting receptor activation?
- Blocking presynaptic ACh release (reduces activation of both nicotinic and muscarinic receptors)
- Directly blocking muscarinic receptors
- Directly blocking nicotinic receptors
- Increasing acetylcholinesterase activity
Correct Answer: Blocking presynaptic ACh release (reduces activation of both nicotinic and muscarinic receptors)
Q49. Which receptor subtype is mainly responsible for contraction of bronchial and gastrointestinal smooth muscle and is therefore a key target in bronchospasm and gut motility?
- M3 muscarinic receptors
- M2 muscarinic receptors
- Nicotinic Nn receptors
- M4 muscarinic receptors
Correct Answer: M3 muscarinic receptors
Q50. Enteric nervous system control of peristalsis relies heavily on which cholinergic receptor subtypes located on smooth muscle and neurons?
- M3 (effector) and M1 (neuronal) muscarinic receptors
- Nm nicotinic receptors only
- M4 and M5 exclusively
- Beta-adrenergic receptors
Correct Answer: M3 (effector) and M1 (neuronal) muscarinic receptors
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