KAAP220 Lecture Notes - Lecture 19: Electrical Synapse, Channel Types, Upper Set

• School: University of Delaware
• Department: Kinesiology & Appl Physiology
• Course: KAAP220
• Professor: Rebecca Lufler

Document Summary

At resting membrane potential, chemically gated sodium channels are all closed gates open, sodium rushes into the cell; influx of positive charge reduces membrane potential; shift from resting membrane potential (-70mv) toward more positive values (less negative) = depolarizes. A neuron receives graded potentials at its dendrites/cell body. Resting membrane potential - voltage-gated sodium and potassium channels are both closed. Need depolarization to threshold - initial stimulus makes a graded depolarization large enough to open voltage-gated sodium channels; threshold = membrane potential at which channels open (about -60 to -55 mv) Activation of sodium channels - rapid depolarization; sodium ions rush inside the cell; rapid depolarization occurs from sodium influx, membrane potential goes from -60 mv to a positive value. Inactivation of sodium ion channels; activation of potassium ion channels. As membrane potential approaches +30 mv, inactivation gates of sodium channels close (sodium channel inactivation)