Cholinergic and Muscarinic Receptors

Question 1

What does it mean to be a cholinergic receptors?

Answer 1

receptors that are sensitive to ACh

Question 2

**What are the two classes of cholinergic receptors?

Answer 2

1. G protein linked (muscarinic receptors)

2. ligan gated ion channels (nicotinic receptors)

Question 3

What are M1, M2, M3 and where are they expressed?

Answer 3

• M1, M2, and M3 are the three muscarinic receptors that are known to have physiological functions
• they are expressed in various organs and couple to different signaling mechanism=diverse receptor functions.

Question 4

Where are M1, M2, and M3 located?

Answer 4

• smooth muscle
• cardiac muscles
• most exocrine glands
• blood vessels of the major vascular beds
• cortical and subcortical sites in the CNS (cerebral and sub-cerebral cortex)

Question 5

**What is the structure of nicotinic receptors?

Answer 5

pentomeric transmembrane polypeptides, subunits form a cation-selective channel permeable to SODIUM and POTASSIUM.
(-two main subtypes: Nm-muscle cell R and Nn-neuronal nicotinicR)

Question 6

**Where are nicotinic receptors located?

Answer 6

Nn: on plasma membranes of PS and S POSTganglionic cells in the autonomic ganglia (and expressed in cortical and subcortical nuclei in the brain)

Nm: on the membranes of skeletal muscle

Question 7

M1

Answer 7

activates myenteric plexus

Question 8

M2

Answer 8

decreases HR

Question 9

M3

Answer 9

contacts:
-circular ciliary muscle
-bronchiolar muscle
-GI smooth muscle
-bladder detrusor muscle
stimulates:
-secretions of GI tract
-eccrine sweat glands
-tear glands
-salivary glands