Question

M2 receptors are present on which of the following?

a. Heart, postganglionic parasympathetic nerves
b. Parasympathetic ganglia, nasal submucosal glands
c. Airway smooth muscle, submucosal glands
d. Postganglionic cholinergic nerves, possible effect on CNS

Answer 1

M2 receptors are present on the heart, postganglionic parasympathetic nerves, parasympathetic ganglia, nasal submucosal glands, and airway smooth muscle, submucosal glands. The postganglionic parasympathetic fibers release acetylcholine (ACh), which binds to M2 receptors in these organs and tissues, leading to rest-and-digest responses.

Step-by-step explanation:

M2 receptors are present on the following:

1. a. Heart, postganglionic parasympathetic nerves
2. b. Parasympathetic ganglia, nasal submucosal glands
3. c. Airway smooth muscle, submucosal glands

The postganglionic parasympathetic fibers release acetylcholine (ACh), which binds to M2 receptors in these organs and tissues, leading to rest-and-digest responses. These receptors are part of the muscarinic receptors group, which are G protein-coupled receptors and do not exclusively cause depolarization of the postsynaptic membrane.