ANPS 019 Lecture Notes - Lecture 15: Electrical Synapse, Axon Terminal, Myelin
5 Oct 2018
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Document Summary
Principal mehcniams neurons use to communicate over long distance. Only seen in cells with excitable membranes. Involvees temporary reversal of polarity across plasma membrane. Graded potentials trigger acgtion potentials at the aoxn potential. Voltage gated na channels transition between 3 conformational states. Three different functional confirmations: closed, opened, inactivated. Voltage gated k+ channels have delayed opening kinetics. Opening delayed compared to voltage gated na+ channel. Voltage sensitive gate that is closed at rest and opens following depolarization. The action potential is an all or nothing event. If threshold is reached, an action potential is generated. If threshold is not reached, an action potential is not generated. Action potentials are always the same, they do not get bigger with greater polarization. Factors influencing velocity of nerve signal: diameter of axon. Large diameter, less resistance to local current flow, faster the velocity of signal. Action potentials are only generated at nodes of ranvier.
