potential
(pŏ-ten'chăl 
)
[L. potentialis, powerful]
- Existing in possibility; latent.
- In electricity, voltage or electrical pressure. It is a condition in which a state of tension or pressure, capable of doing work, exists. When two electrically charged bodies of different potentials are brought together, an electric current passes from the body of high potential to that of low.
ABBR: AP
A local reversal of the charge across an excitable cell membrane that is propagated along the length of the membrane. In humans, most of the cells that conduct action potentials are neurons or muscles. Neurons and muscle cells actively maintain an excess of negative ions inside the cell, which gives them a cross-membrane charge of about –75 to –80 mV. If ion channels in one area of the membrane are caused to open briefly, then charged ions move across the membrane, reducing the charge differential. When the cross-membrane charge reaches a threshold level (often about –40 to –60 mV), sodium ion channels (voltage-sensitive or voltage-gated channels) open in the vicinity. Sodium ions rush into the cell, and the cross-membrane potential temporarily rises to a peak of about +40 to +50 mV, the height of the action potential in that region. This flood of ions also depolarizes adjacent membrane regions, which quickly reach their threshold levels, opening their voltage-gated channels. In this way, the depolarization spreads along the membrane.after p.The small ionic changes across an excitable membrane that follow an action potential.
demarcation p.The difference in electrical potential between an intact longitudinal surface and the injured end of a muscle or nerve. SYN: injury potential.
evoked p.The electroencephalographic record of electrical activity produced at one of several levels in the central nervous system (CNS) by stimulation of an area of the sensory nerve system. Evoked potentials differ from the spontaneous electrical activity in the nervous system in that they are potentials that arise in response to an induced stimulus, such as exposure to sound, touch, or a source of light. Analysis of the response can provide important information concerning the function of the peripheral and central nervous systems. SYN: evoked response.
field p.The electrical potential in the fluid-filled extracellular space that surrounds a neuron or group of neurons. SYN: local field potential.
injury p.Demarcation potential.
late p.Deflections found on signal-averaged electrocardiograms that follow the QRS complex and point to an increased likelihood of ventricular dysrhythmias. These deflections represent delays in electrical conduction through the ventricles.
liquid junction p.The potential voltage developed in an electrode measurement system at the point where two solutions are in contact. Most often the solutions are the test solution and a liquid bridging solution such as saturated potassium chloride (KCl) although any liquid-liquid interface may be involved. An example is the pH reference electrode.
local field p.Field potential.
membrane p.The electrical charge or potential difference between the inside and outside of a cell membrane.
spike p.A change in potential that occurs when a cell membrane is stimulated.
transcranial magnetic motor-evoked p.
ABBR: tcMMEP
Intraooperative electrical stimulation of scalp nerves to monitor the responses of structures in the CNS and prevent neurosurgical trauma.