8.2 ANS

Question 1

Steps of neurotransmission.

Answer 1

1. Uptake of precursor
2. Synthesis of transmitter
3. Vesicular storage of transmitter (which either degrades or…)
4. Depolarisation by action potential
5. Depolarisation dependent influx Ca2+
6. Exocytotic release of transmitter
7. Diffusion to post-synaptic membrane
8. Interaction with post-synaptic receptors
9. Inactivation of transmitter/re-uptake/interaction with pre-synaptic

Question 2

How is acetyl choline synthesised?

Answer 2

Acetyl coA + Choline ==> Acetylcholine + coenzyme A

Uses Choline Acetyltransferase (CAT)

Question 3

How is acetylcholine degraded?

Answer 3

Acetylcholine ==> acetate + choline

Uses acetylcholine esterase (AChE)
Note both sides of synapses coated with this enzyme - rapid degradation! Not 100% efficient though so transmitter still has time to pass on signal

Question 4

For cholinergic receptors, how can drugs be specific to autonomic ganglia/NM junction?

Answer 4

Because nAChRs and mAChRs differ in structure

Question 5

How can ACh action be enhanced in particular diseases?

Answer 5

To treat myasthenia graves and alzheimer’s, AChE inhibitors (acetylcholine esterase inhibitors) limit rate of breakdown

Question 6

Disadvantage of cholinergic drugs?

Answer 6

E.g. Non selective mAChR agonist
Lack selectivity and reach unwanted side effects
- decrease heart rate and cardiac output
- increase bronchoconstriction and GI tract peristalsis (smooth muscle)
- increase sweating and salivation (exocrine glands)

Question 7

What is SLUDGE?

Answer 7

Symptoms if ingested magic mushrooms
Cause overstimulation of mAChR in organs and muscles innervated by PNS
Salivation
Lacrimation
Urination
Defecation
Gastrointestinal Upset
Emesis (vomiting)