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Unformatted text preview: he last step of chemical synaptic transmission is inactivation or removal of transmitter. all chemical
synapse is important that action of transmitter is short (millisecond). so synapse can reset itself
and participate in further transmission of info.
-there are 3 ways for removal of neurotransmitter.
1. the first arrow indicate that neurotransmitter in synaptic cleft can be degraded by degrative
enzyme (hydrolytic enzyme) that can exist either 1. bind to post 2. pre membrane 3. extracellular
matrix that fill synaptic cleft. by hydrolysis, the neurotransmitter will be broken down into inactive
products so transmission will cease.
2. the middle arrow shows that neurotransmitter can diffuse away from synaptic cleft and therefore
its concentration go down. in like CNS, this action is very important in terminating action of
3. neurotransmitter can be reuptake back to presynaptic terminal through sodium-dependent
secondary active transport system. once inside the presynaptic terminal, the neurotransmitter can
be recycle, broken down, or repackage into synaptic vesicle again. T 1 P 4
T Receptor synaptic cleft T T diversity, disease, of chemical synaptic transmission. how synapse work 5 re-uptake
diffusion 1. Synthesis
3. Release Postsynaptic
Terminal 4. Receptor Interaction
(ionotropic or metabotropic)
5. Inactivation enzyme when neurotransmitter bind to receptor (ioniotropic, metabotrophic-cell signaling pathway like).
many different response can occur at chemical synapse.
-when ion channel open through neurotransmitter, if it's sodium ion channel more sodium will
come in (if cell have normal negative resting potential, the force is negative) cause excitatory
PSP (depolarization, the postsynap tend to generate action potential).
-EPSP/excitation (glutamate act through AMPA type receptor open sodium channel, depolarizes
neuron) can be 1. current move potential toward threshold or better 2. (threshold is a state of
cell that lead to all-or-not AP). Depolarization lead to more sodium channel (so...
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This document was uploaded on 03/09/2014 for the course EXSC 301 at USC.
- Spring '09