L8 - drugs affecting neuromuscular transmission

Question 1

how is acetylcholine synthesised

Answer 1

choline + acetylcoenzyme A by action of the enzyme choline acetyl transferase

Question 2

what drug blocks the uptake of choline into the nerve terminal

Answer 2

hemicholinum

Question 3

what drug blocks the uptake of acetylcholine into synaptic vesicles

Answer 3

vesamicol / AH5183

Question 4

what are the two types of acetylcholine receptor

Answer 4

nicotinic and muscarinic

Question 5

drugs that prevent the destruction of ACh

Answer 5

edrophonium (short duration), neostigmine (nedium duration), irreversible organophosphates e.g novichok (long duration)

Question 6

what is a motor unit

Answer 6

the motor nerve + the nerve fibres it enervates

Question 7

how large is the neuromuscular gap

Answer 7

around 60nm

Question 8

what neurotransmitters and reactors are active at neuromuscular junction

Answer 8

acetylcholine and nicotinic receptors

Question 9

structure of the nicotinic Ash receptor

Answer 9

⍺⍺β𝛄σ subunits around a non-selective cation channel, permeable to Na+ and K+

Question 10

when does the nicotinic Ash receptor channel open

Answer 10

when 2 molecules of Ash bind to the protein complex, on to each ⍺ subunit. opening of the channel leads to depolarisation of the end-plate region of the muscle membrane.

Question 11

what does botulinum toxin do

Answer 11

destroys key proteins involved in exocytosis
clinical used to treat blepharospasm, spasticity associated with MS or cerebral palsy, cluster headache and in cosmetics

Question 12

clinical uses of reversible, competitive antagonists at neuromuscular junctions

Answer 12

used as muscle relaxants during surgery. effects last for 15-40 minutes.

Question 13

name a depolarising muscle relaxant

Answer 13

suxamethodium. same effect as acetylcholine but can’t be broken down