Chapter 2 Flashcards

action potential
The electrical signal conducted along axons (or muscle fibers) by which information is conveyed from one place to another in the nervous system.
active transporters
Transmembrane proteins that actively move ions into or out of cells against their concentration gradients. Their source of energy may be ATP or the electrochemical gradients of various ions.
Displacement of a cell's membrane potential toward a less negative value.
electrochemical equilibrium
The condition in which no net ionic flux occurs across a membrane because ion concentration gradients and opposing transmembrane potentials are in exact balance.
equilibrium potential
The membrane potential at which a given ion is in electrochemical equilibrium.
The displacement of a cell's membrane potential toward a more negative value.
ion channels
Integral membrane proteins possessing pores that allow only certain ions to diffuse across cell membranes, thereby conferring selective ionic permeability.
Nernst equation
A mathematical formula that predicts the electrical potential generated ionically across a membrane at electrochemical equilibrium.
overshoot phase
The peak, positive-going phase of an action potential, caused by high membrane permeability to a cation such as Na+ or Ca2+.
passive flow
The flow of electrical current across neuronal membranes that does not entail the action potential mechanism.
receptor potential
The membrane potential change elicited in receptor neurons during sensory transduction. Also called generator potential.
rising phase
The initial, depolarizing, phase of an action potential, caused by the regenerative, voltage-dependent influx of a cation such as Na+ or Ca2+.
threshold potential
The level of membrane potential at which an action potential is generated.
The final, hyperpolarizing phase of an action potential, typically caused by the voltage-dependent efflux of a cation such as K+.