action potential (redirected from depressed fast response action potential)

potential /po·ten·tial/ (po-ten´shal)

1. existing and ready for action, but not active.

2. the work per unit charge necessary to move a charged body in an electric field from a reference point to another point, measured in volts.

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action potential  (AP) the electrical activity developed in a muscle or nerve cell during activity.

after-potential  afterpotential.

electric potential , electrical potential potential (2).

evoked potential  (EP) the electrical signal recorded from a sensory receptor, nerve, muscle, or area of the central nervous system that has been stimulated, usually by electricity.

membrane potential  the electric potential existing on the two sides of a membrane or across the cell wall.

resting potential  the potential difference across the membrane of a normal cell at rest.

spike potential  the initial, very large change in potential of an excitable cell membrane during excitation.

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action potential

n.

The change in membrane potential occurring in nerve, muscle, or other excitable tissue when excitation occurs.

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action potential,

an electric impulse consisting of a self-propagating series of polarizations and depolarizations, transmitted across the plasma membranes of a nerve fiber during the transmission of a nerve impulse and across the plasma membranes of a muscle cell during contraction or another activity. In the absence of an impulse, the inside is electrically negative and the outside is positive (the resting potential). During the passage of an impulse at any point on the nerve fiber, the inside becomes positive and the outside, negative. Also called action current.

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action potential 

the electrical activity developed in an excitable cell when stimulated; it may be elicited by electrical, chemical, or mechanical stimulation, by temperature change, and so on.

On an electrocardiogram, action potential is seen as the cardiac cycle of a single cell, produced by a rapid sequence of changes at the cell membrane, and consists of phase 0 to phase 4, with phases 0 to 3 representing electrical systole and phase 4 representing electrical diastole. The characteristics of action potentials vary in different parts of the heart; for example, the cells of the sinoatrial and atrioventricular nodes and the atrial cells do not have phases 1 or 2 and are shorter in duration than those of the His-Purkinje system and the ventricles.

depressed fast response action potential an action potential produced when some but not all of the fast sodium channels are available to depolarize the fiber; on an electrocardiogram, it signifies the presence of slow conduction.

fast response action potential the action potential produced by a cell when all of the fast sodium channels are available for depolarization; on an electrocardiogram, it signifies rapid upstroke velocity and maximal amplitude for phase 0, with consequent optimal conduction velocity.

slow response action potential the action potential produced when only slow channels are available to depolarize the fiber; it is normal only in the sinoatrial and atrioventricular nodes and results in very slow conduction.

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action potential,

n 1. an electric impulse consisting of a self-propagating series of polarizations and depolarizations, transmitted across the cell membranes of a nerve fiber during the transmission of a nerve impulse and across the cell membranes of a muscle cell during contraction.
n 2. the electrical potential developed in a muscle or nerve during activity.

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action potential

the nerve impulse, the sign of activity and the basis of activity in individual neurons in the nervous system. The measure of the activity of an individual nerve cell is indicated by the frequency of its discharge.

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compound action potential

the sum of the activity in a number of nerve fibers. It applies to the degree of activity in a nerve trunk in which a variable proportion of nerve fibers are discharging.

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action potential

Cardiology The constellation of changes in electric potential generated by myocardial cell membranes after stimulation Physiology The sequential, electrochemical polarization and depolarization that traverses the membrane of a neuron in response to mechanical stimulation–eg, touch, pain, cold, etc. See Depolarization.