Acetylcholine

Question 1

Primary transmitter in the parasympathetic nervous system

Answer 1

Acetylcholine

Question 2

Two families of cholinergic receptors

Answer 2

Nicotinic
Muscarinic

Question 3

Nicotinic receptor type

Answer 3

Ion

Question 4

Muscarinic receptor type

Answer 4

GPCR

Question 5

Location of acetylcholine synthesis

Answer 5

Presynaptic nerve terminal

Question 6

Rate limiting factor in acetylcholine synthesis

Answer 6

Availability of the subtrates choline and acetyl-CoA

Question 7

Step-by-step ACh synthesis

Answer 7

1. Acetyl CoA is produced in the mitochondria and released to the cytoplasm
2. Choline is transported from the blood into the cytoplasm of the nerve terminal
3. Choline and Acetyl CoA joined by the enzyme choline acetyltransferase to form ACh
4. ACh is packaged into vesicles

Question 8

Step-by-step of ACh release

Answer 8

1. Action potential depolarizes the nerve terminal
2. Voltage gated Ca++ channels open and allow an influx of Ca++ into the nerve terminal
3. ACh vesicles to fuse the nerve terminal (Ca++ is required) and release ACh via exocytosis into the synaptic cleft

Question 9

Antagonizes Ca++ at the presynaptic nerve terminal

Answer 9

Mg++

Question 10

Step-by-step metabolism of ACh

Answer 10

1. Ache around cholinergic receptors hydrolyzes ACh after it unbinds = choline and acetate
2. Choline diffuses into circulation. Acetate diffuses away from the synaptic cleft.
3. Choline is transported back into the nerve terminal to serve as substrate for ACh synthesis

Question 11

Two subtypes of nicotinic ACh receptors

Answer 11

Nm (muscle)
Nn (neuron)