Pre-synaptic membrane: 1. Action potential arrives, Ca2+ channels open. 2. Ca2+ ions enter axon terminal 3. Vesicles fuse with presynaptic membrane 4. Neurotransmitter released to synaptic cleft
Postsynaptic neuron: a. Neurotransmitter bind with ion channels at receptor site. b. Ion channels open & ions enter postsynaptic neuron. c Generates postsynaptic potential d Neurotransmitter removed from receptor site e Channels close
- Post-synaptic summation: A single PSP is insufficient to trigger a new action potential, so:
- Generator potential build up is slow + graded. GP integrates changes cause by multiple action potentials across time and space.
Neurotransmitter removal: Neurotransmitters don't change when they bind to a receptor. They have to be actively removed to stop influence on post-synaptic cell.
2 types of neurotransmitter removal = 1. Degradation - enzymes in cleft break them down. Partly recycled. 2. Reuptake - receptors at pre-synaptic axon terminal take up NT's and return into pre-synaptic cell.
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