Neuromuscular Junction

Question 1

What is a neuromuscular junction?

Answer 1

• where a motor neuron meets a muscle end plate
• nt released into neuromuscular gap and binds to receptors on muscle membrane

Question 2

What is the size of the neuromuscular gap?

Answer 2

60nm

Question 3

What nt acts on skeletal muscle receptors?

Answer 3

• acetylcholine, ACh

Question 4

What type of receptor is on muscle membranes?

Answer 4

• nicotine acetylcholine receptors, nAChRs

Question 5

In what ways can drugs target neuromuscular transmission?

Answer 5

• synthesis
• storage
• release
• receptor interactions (best)
• nt termination

Question 6

Describe neuromuscular transmission

Answer 6

1. depolarisation of motor neuron
2. voltage-gated ca2+ channels open
3. influx of ca2+ causes vesicles to fuse to membrane
4. ACh released via exocytosis
5. ACh activates nAChRs on muscle membrane
6. depolarisation of muscle end plate
7. action potential in muscle end plate spreads across muscle surface, causing muscle contraction

Question 7

How is ACh made?

Answer 7

• choline and acetylcoenzymeA
• via enzyme choline acetyl transferase (CAT)

Question 8

Describe pre-junctional events

Answer 8

• choline taken into nerve terminal via transport protein
• ACh made (choline + acetylCoA)
• ACh stored in vesicles