EDAIC MCQ (Multiple Choice Question) and answer. FREE UPLOADS BY WWW.TARGETEDAIC.COM (76mcq)

The section, EDAIC MCQ (Multiple Choice Question) and answer, covers a different topic each day with the intent that candidates can prepare one small topic each day, making steady progress in their exam preparation.

Question: Identify the statements that correctly describe muscarinic receptors:
A. They are pentameric ion channels
B. They are G-protein-coupled receptors
C. The M1 subtypes increase potassium conductance in the sino-atrial node
D. The M2 subtypes are found in atrial tissue
E. Stimulation of the M1 receptor increases gastric acid secretion

Answers:

1. 1. False
   2. True
   3. False
   4. True
   5. True

Explanation:

Types of Cholinergic receptors

• nicotinic (pentameric ion channels) or
• muscarinic (G-protein-coupled) receptors.

Types of muscarinic receptors: five subtypes, of which M1, M2 and M3 are the most important.

• M1 is a Gq-protein coupled receptor that is found in autonomic ganglia and
  gastric parietal cells. Stimulation of the M1 receptor causes activation of
  phospholipase C, resulting in reduced membrane potassium conductance and
  depolarization of the membrane.
• M2 is a Gi-protein coupled receptor found in atrial tissue, in the SA and
  AV nodes. Activation reduces intracellular cAMP and increases membrane
  potassium conductance, hyperpolarizing the membrane.
• M3 is a Gq-protein coupled receptor that is found in glands and visceral
  smooth muscle.

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‘EDAIC MCQ (Multiple Choice Question) and answer’ covers a different topic each day with the intent that candidates can prepare one small topic each day, making steady progress in their exam preparation.