Lecture_3-Neurotransmission_Review

Parts of a neuron terminal terminals have many of the

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Parts of a Neuron-terminal Terminals have many of the organelles that are localized in the nucleus In particular, the terminals contain mitochondria (energy) as well as enzymes to synthesize neurotransmitters Terminals can make contact with dendrites, axons and other terminals
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Exocytosis of synaptic vesicles into the synaptic cleft (extracellular fluid)
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Release of Neurotransmitters SNAREs: vesicle-associated membrane protein (VAMP) or synaptobrevin (on vesicle so v-SNARE) syntaxin (in active zone t-SNARE (target)) synaptosomal-associated protein of 25 kDa (SNAP-25) (in active zone=t-SNARE) Toxins and Vesicular Release Botulism: “protase”; cleaves t- and v-SNAREs Tetanus: Protase; inhibits v-SNAREs cause inhibition of release paralysis
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“Reserve Pool” Synapsins: -Bind to vesicles and anchor them to actin -their activation by kinases causes them to dissociate from vesicles -vesicles move to active zone
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Calcium’s role in Release - Synaptotagmin : Calcium-sensing protein that is anchored to the vesicle membrane; has 2 calcium-sensing regions on its cytoplasmic region -regulated by complexins
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Ending Neurotransmission -2 major mechanisms to end neurotransmission 1- reuptake : transporters in the terminals (or on the dendrites) take the neurotransmitter back inside the neuron to be re-packaged or degraded 2- enzymatic degradation : enzymes found in the synaptic cleft break down the neurotransmitter after it is released (oxidases, esterases=non-synthetic reactions) 3- diffusion : neurotransmitters simply move out of the synaptic cleft
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Policing Neurotransmission - Autoreceptors : receptors that are located on the edges of the active zone on the presynaptic terminal ; regulate calcium channels and the machinery involved in exocytosis
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Parts of a Neuron terminal Terminals have many of the...

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