Acetylcholine Flashcards
1
Q
Primary transmitter in the parasympathetic nervous system
A
Acetylcholine
2
Q
Two families of cholinergic receptors
A
Nicotinic
Muscarinic
3
Q
Nicotinic receptor type
A
Ion
4
Q
Muscarinic receptor type
A
GPCR
5
Q
Location of acetylcholine synthesis
A
Presynaptic nerve terminal
6
Q
Rate limiting factor in acetylcholine synthesis
A
Availability of the subtrates choline and acetyl-CoA
7
Q
Step-by-step ACh synthesis
A
- Acetyl CoA is produced in the mitochondria and released to the cytoplasm
- Choline is transported from the blood into the cytoplasm of the nerve terminal
- Choline and Acetyl CoA joined by the enzyme choline acetyltransferase to form ACh
- ACh is packaged into vesicles
8
Q
Step-by-step of ACh release
A
- Action potential depolarizes the nerve terminal
- Voltage gated Ca++ channels open and allow an influx of Ca++ into the nerve terminal
- ACh vesicles to fuse the nerve terminal (Ca++ is required) and release ACh via exocytosis into the synaptic cleft
9
Q
Antagonizes Ca++ at the presynaptic nerve terminal
A
Mg++
10
Q
Step-by-step metabolism of ACh
A
- Ache around cholinergic receptors hydrolyzes ACh after it unbinds = choline and acetate
- Choline diffuses into circulation. Acetate diffuses away from the synaptic cleft.
- Choline is transported back into the nerve terminal to serve as substrate for ACh synthesis
11
Q
Two subtypes of nicotinic ACh receptors
A
Nm (muscle)
Nn (neuron)