Neuroscience: Exploring the Brain - Chapter 4 Key Terms Flashcards

Chapter 4 Key Terms and Definitions

314897260	rising phase	The first part of an action potential, characterized by a rapid depolarization of the membrane.
314897261	overshoot	The part of an action potential when the membrane potential is more positive than 0 mV.
314897262	falling phase	The part of an action potential characterized by a rapid fall of membrane potential from positive to negative.
314897263	undershoot	The part of an action potential when the membrane potential is more negative than at rest; also called after-hyperpolarization.
314897264	after-hyperpolarization	The hyperpolarization that follows strong depolarization of the membrane; the last part of an action potential, also called undershoot.
314897265	threshold	A level of depolarization sufficient to trigger an action potential.
314897266	absolute refractory period	The period of time, measured from the onset of an action potential, during which another action potential cannot be triggered.
314897267	relative refractory period	The period of time following an action potential during which more depolarizing current than usual is required to achieve threshold.
314897268	voltage clamp	A device that enables an investigator to hold the membrane potential constant while transmembrane currents are measured.
314897269	voltage-gated sodium channel	A membrane protein forming a pore that is permeable to Na+ ions and gated by depolarization of the membrane.
314897270	patch clamp	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.
314897271	channelopathy	A human genetic disease caused by alterations in the structure and function of ion channels.
314897272	tetrodotoxin (TTX)	A toxin that blocks Na+ permeation through voltage-gated sodium channels, thereby blocking action potentials.
314897273	voltage-gated potassium channel	A membrane protein forming a pore that is permeable to K+ ions and gated by depolarization of the membrane.
314897274	saltatory conduction	The propagation of an action potential down a myelinated axon.
314897275	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.