BSCI 207 Lecture Notes - Lecture 32: Schwann Cell, Triage, Threshold Potential
26 Nov 2018
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Bsci 207, dr. bretton kent - friday, november 16, 2018. Cell body- integrates incoming signals to generate outgoing signal. Axon- passes electrical signals to dendrites of another cell or effector. Resting state- positive outside, more negative inside, neither channel. Depolarizing phase- more positive inside (sodium in), negative outside. Repolarizing phase- positive outside (potassium out), negative inside. Double-gated channel (unusual), each gate works at different voltages. Ions can diffuse faster than channels can open or close. Action potential moves calcium movement into cell, moving vesicles. Vesicles fuse with membrane and release neurotransmitter. Neurotransmitter binds to ion channel, causes change in postsynaptic cell potential. Speed correlated with axonal diameter (like bigger straw) Schwann cells(lipid rich)- ion-impervious regions that prevent depolarization. Nodes of ranvier- excitable areas between schwann cells. Action potential skips from node to node 10x faster. Decreases possibility of postsynaptic membrane action potential. Reduces resting potential, less likely to reach threshold potential.
