Also found in: Dictionary, Thesaurus, Encyclopedia.
existing and ready for action, but not active.
electric tension or pressure.
action potential see action potential.
after-potential the period following termination of the spike potential.
auditory evoked potential in electroencephalography, changes in waves in response to sound; see also brainstem auditory evoked potential.
brainstem auditory evoked potential that portion of the auditory evoked potential that comes from the brainstem; abnormalities can be analyzed to evaluate comas, to support diagnosis of multiple sclerosis, and to detect early posterior fossa tumors.
cognitive event--related p's a diagnostic study that uses electroencephalographic equipment and a computer dedicated to analyze brain wave P300; this wave is a measure of the brain's active cognitive processing of information. The patient is instructed to complete a task that requires attention and information processing. A recording of brain wave activity as well as information related to cognitive function is produced.
diastolic potential the transmembrane potential of the cell during electrical diastole.
maximal diastolic potential the most negative level attained during the cardiac cycle by the cell membrane of a fiber that does not have a constant resting potential, occurring at the end of phase 3 of the action potential. In pacemaker cells this is a point of hyperpolarization.
membrane potential the electric potential that exists on the two sides of a membrane or across the wall of a cell.
resting potential (resting membrane potential) the difference in potential across the membrane of a cell when it is at rest, i.e., fully repolarized. In cardiac physiology this occurs during electrical diastole in pacemaker cells and continuously in nonpacemaker cells.
spike potential the initial, very large change in potential of the membrane of an excitable cell during excitation.
threshold potential the transmembrane potential that must be achieved before a membrane channel can open; it differs among the various cardiac membrane channels.
the main wave in the action potential of a nerve; it is followed by negative and positive afterpotentials.
spike potentialNeurology A single rapid, 100–200 msec voltage 'transient' that occurs spontaneously in electromyography in smooth muscle cells, when they have resting membrane potentials above the SP threshold, as occurs in the lower esophageal sphincter. See M spike.
spike po·ten·tial(spīk pŏ-ten'shăl)
The main wave in the action potential of a nerve; it is followed by negative and positive afterpotentials.