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The first part of an action potential, characterized by a rapid depolarization of the membrane.
THe part of an action potential when the membrane potential is more positive than 0mV.
THe part of the action potential where the inside of the neuron is positively charged with respect to the outside.
The part of an action potential characterized by a rapid fall of membrane potential from positive to negative.
A rapid repolarization until the membrne is actually more negative than than the resting potential.
The part of an action potential when the membrane potential is more negative than at rest; also called after-hyperpolarization
The hyperpolarization that follows strong depolarization of the membrane; the last part of an action potential; also called undershoot.
A level of depolarization sufficient to trigger an action potential.
absolute refractory period
THe period of time, measured from the onset of an action potential, during which another action potential cannot be triggered.
relative refractory period
The period of time following an action potential during which more depolarizing current than usual is required to achieve threshold.
A device that enables an investigator to hold the membrane potential constant while transmembrane currents are measured.
voltage-gated sodium channel
A membrane protein forming a pore that is permeable to Na+ ions and gated by depolarization of the membrane.
A method that enables an investigator to hold constant the membrane potential of a patch of membrane while current through a small number of membrane channels is measured.
A human genetic disease caused by alterations in the structure and function of ion channels.
A toxin that blocks Na+permeation through voltage gated sodium channels, thereby blocking action potentials.
voltage gated potassium channel
A membrane protein forming a pore that is permeable to K+ ions and gated by depolarization of the membrane.
The propagation of an action potential down a myelinated axon.
when action potentials only conduct in one direction (normally)
backwards propagation is called antidromic conduction (usually done experimentally)
typical action potential rate, over a 2 cm length of axon.
spike initiation zone
A region of the neuronal membrane where action potentials are normally initiated, characterized by a high density of voltage gated sodium channels.