neuromuscular junction Flashcards
(10 cards)
What is a neuromuscular junction?
Specialised form of synapse between a motor neurone and the surface membrane of a skeletal muscle fibre
How does the transmission across a neuromuscular junction start?
Arrival of action potentials at the synaptic knob causes depolarisation of presynaptic membrane
What does this stimulate?
Calcium ion channels to open and calcium ions to diffuse into the synaptic knob
What does this allow?
Vesicles containing acetylcholine to move and merge with the presynaptic membrane
What happens to the acetylcholine?
It diffuses across the synaptic cleft
What happens then?
It attaches to specific protein receptors on the sarcolemma
What does this attachment stimulate?
Entry of sodium ions causing depolarisation
What does this result in?
An action potential along the sarcolemma and into the muscle fibre releasing calcium ions
What happens to acetylcholine?
It is hydrolysed by acetyl cholinesterase
What happens to these products?
They are taken up by active transport into the synaptic knob and acetylcholine is re-synthesised with ATP
