L07: Neuromusclar Junction Flashcards
What is a neuromuscular junction
The point at which a neurone and a muscle meet
How are neurotranmitters released at the neuromuscular junction
1) action potential arrives at the pre-synaptic terminal
2) depolarisation causes voltage gated calcium channels to open
3) calcium influx occurs
4) calcium is sensed by synpatogomin which calcium binds to
5) synaptogomin undergoes conformational change
6) exocytosis of neurotransmitter vesicles occurs
If acetylcholine neurotransmitter is released which report does it bind to
Nicotinic ach receptors
How many ach has to bind to nicotinic receptors
2
What happens when ach binds to nicotinic receptors
Nicotinic receptors undergoes conformational change
Sodium influx occurs
Action potential is re triggered
What is an end plate potential
End plate potential is caused by nicotinic receptors which go onto trigger the opening of voltage gated sodium channel to cause action potential
How does action potential cause muscle contraction
1) action potential penetrates through the T-tubules
2) on the t-tubules there are DHP receptors which is attached to a calcium release channel
3) depolarisation causes DHP receptor to undergo conformational channel and release calcium from the sarcoplasmic reticulum
4) calcium causes muscle contraction
How is calcium removed in repolarisation
Calcium is brought back into the sarcoplasmic reticulum and attaches to a protein called calsequestrin
How is neurotransmitter removed at the post-synaptic membrane
Re-uptake of neurotransmitter
OR
Ezymeatic breakdown
Describe the enzymatic breakdown of acetycholine
Ach is Brocken down by acertycholinesterase into choline and acetate
Choline is taken back into the neurone to make it into ach
What is the causes of myasthenia gravis
Loss of post synaptic receptors of nicotinic ach receptors
What is the treatment for myasthenia gravis
Ache inhibitors
What do ache inhibitors do
Block the enzyme acetycholinesterase from breaking ach so there is a longer contraction
