Session 5: Synaptic Transmission

Question 1

Define neuromuscular junction.

Answer 1

The synapse between a nerve and a skeletal muscle fibre.

Question 2

Why can the internal concentration of calcium in the pre-synaptic knob be raised so significantly?

Answer 2

The concentration of calcium inside the pre-synaptic knob is so low (1x10^-7M)

Question 3

How can you increase the amount of neurotransmitter released?

Answer 3

Increase the frequency of AP

Question 4

Describe the molecular chemistry of a calcium channel.

Answer 4

• 1 subunit (4 alpha helix units)
• S4 voltage sensor region (high positive density)
• Pore

Question 5

What enzyme is required to break down ACh?

Answer 5

Acetylcholine esterase

Question 6

What happens after the neurotransmitter is brought close to the post-synaptic knob?

Answer 6

A snare complex forms making a fusion pore

Question 7

Name the 2 types of nicotinic ACh receptor blockers

Answer 7

1. Depolarising blockers

2. competitive blocker

Question 8

Give an example of a competitive blocker

Answer 8

Tubocurarine (d-TC)

Question 9

Give an example of a depolarising blocker

Answer 9

Succinylcholine

Question 10

How can the affects of Tubocurarine (d-TC) be overcome?

Answer 10

Increase the concentration of ACh

Question 11

Name an autoimmune disease which targets nACh receptors.

Answer 11

Mayasthenia gravis

Question 12

What is Mayasthenia gravis?

Answer 12

Patients suffer profound weakness as nAChR is degraded by antibodies meaning the end-plate potential fails to reach threshold.

Question 13

What type of channel is nAChR?

Answer 13

LGIC

Question 14

What is the difference between nAChR and mAChR?

Answer 14

nAChR- LGIC

mAChR- coupled to G-proteins