synaptic transmission Flashcards
What happens to the membrane when an action potential arrives at the pre-synaptic knob
The membrane becomes depolarised as sodium is entering through the membrane
What does the depolarisation of the presynaptic membrane cause
Causes voltage-gated calcium channels to open
What happens when voltage gates calcium channels open
Calcium ions enter by diffusion as their is a lower concentration of calcium ions inside the cell than outside
What do the calcium ions do once they enter the pre-synaptic membrane
They bind to synaptic vesicles
What do the vesicles do once calcium ions have binded to them
They fuse with the pre-synaptic membrane
What happens when the vesicles fuse with the pre-synaptic membrane
The neurotransmitter is released into the synaptic cleft via exocytosis
Where does the neurotransmitter go once they are released from the pre-synaptic neurone
It diffuses across the cleft and binds to receptors on the post-synaptic neurone
What are cholinergic synapses
Synapses that use acetylcholine as their neurotransmitter
What are acetylcholine receptors
A special type of sodium ion channel
What happens when 2 acetylcholine molecules bind to the acetylcholine receptors
The sodium ion channel opens
What happens when sodium ion channel opens
Sodium diffuses in, depolarising the post-synaptic neurone
What happens if enough sodium ions diffuse into the post synaptic neurone
The post-synaptic neurone will begin an action potential
What is the last stage in synaptic transmission
Inactivation of the neurotransmitter
Why does inactivation of neurotransmitter occur
If it was not deactivated it would continue to stimulate the post-synaptic neurone
How is the neurotransmitter deactivated
The synapse contains enzymes like acetylcholinesterase which will break down the neurotransmitter into choline and ethanoic acid
