action potential


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Related to action potential: membrane potential, Cardiac action potential

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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

ac·tion po·ten·tial

the change in membrane potential occurring in nerve, muscle, or other excitable tissue when excitation occurs.
Farlex Partner Medical Dictionary © Farlex 2012

action potential

n.
A momentary change in electrical potential on the surface of a cell, especially of a nerve or muscle cell, that occurs when it is stimulated, resulting in the transmission of an electrical impulse.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

Action Potential

An all-or-none electrical event (neural impulse) in an axon or muscle fibre in which the polarity of the membrane potential is rapidly reversed and re-established. Action potentials begin at one end of the axon of a neurone and move along the axon to the other end.
Action potential phases Phase 0 is the period of rapid depolarisation, the reversal of polarity from negative to slightly positive; the remaining 4 phases (1 through 4) are concerned with returning the cell to its resting membrane potential, where it remains until the next stimulus.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

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.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

ac·tion po·ten·ti·al

(ak'shŭn pŏ-ten'shăl)
The change in membrane potential occurring in nerve, muscle, or other excitable tissue when excitation occurs.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

action potential

The electrical signal propagated in nerve and muscle cells. It consists of a zone of reversal of the normal charge on the membrane so that the outside briefly becomes negative relative to the inside, instead of vice versa. This zone of depolarization, which is caused by the opening of ion channels, then moves along the fibre at a rate very much slower than the speed of normal electrical conduction along a wire. Action potentials operate according to an ‘all-or-none’ law. They function fully or not at all.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

action potential

the electrical potential present between the inside and outside of a nerve or muscle fibre when stimulated. In the resting state (RESTING POTENTIAL) the muscle or the nerve fibre is electrically negative inside and positive outside. With the passage of the impulse the charges are reversed and the wave of potential change which passes down the fibre is the most easily observable aspect of an impulse. The impulse (DEPOLARIZATION) is short-lived and lasts for about 1 millisecond, after which time the resting potential is restored. see NERVE IMPULSE.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

ac·tion po·ten·ti·al

(ak'shŭn pŏ-ten'shăl)
The change in membrane potential occurring in nerve, muscle, or other tissue excitation.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
Effect of EPSP and IPSP on the generation of an action potential. (A) The EPSP/IPSP signal is propagated down the dendrite and is summed with other synaptic inputs at the soma.
Electrically evoked compound action potentials of guinea pig and cat: responses to monopolar, monophasic stimulation.
where v is the velocity, [rho] is the density, [[micro].sub.v] is the viscosity, and [F.sub.1](z) is a force from the action potential. In
Let [C.sub.L] (t) indicate left epimyocardium standard action potential of human and let [C.sub.R](t) indicate right epimyocardium standard action potential of human.
As a result, energy supplied by ATP during action potential or subthreshold activity can be calculated based on the H-H model:
For example, electrical stimulation can improve functional maturation (action potential, calcium transient, and contraction force), while mechanical stretch increases cell size and sarcomere structure.
Citation: Zhifen Chen et al., "Subtype-specific promoter-driven action potential imaging for precise disease modelling and drug testing in hiPSC-derived cardiomyocytes," European Heart Journal, 2016; ehw189 DOI: 10.1093/eurheartj/ehw189
Jitter measurement with a CNE have risks, such as the triggering and/or jittering potentials being compound signals due to summation, and showing extra phases rather than a clear single-fiber action potential (18).
2, the decrease in the rate of depolarization of action potential slows intra ventricular conduction and increases the duration of QRS complex.
In motor conduction studies, motor distal latency (MDL) and compound muscle action potential (CMAP) values were recorded for the median and ulnar nerves by stimulating at the level of the wrist and antecubital region in the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles in the upper extremity.

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