wave (wāv) a uniformly advancing disturbance in which the parts moved undergo a double oscillation; any wavelike pattern.
alpha waves see under rhythm.
beta waves see under rhythm.
brain waves the fluctuations of electric potential in the brain, as recorded by electroencephalography.
delta wave
1. an early QRS vector in the electrocardiogram in preexcitation.
2. (pl.) electroencephalographic waves with a frequency below 3.5 per second, typical in deep sleep, infancy, and serious brain disorders.
electromagnetic waves the spectrum of waves propagated by an electromagnetic field, having a velocity of 3 × 108 m/s in a vacuum and including, in order of decreasing wavelength, radio waves, microwaves, infrared, visible, and ultraviolet light, x-rays, gamma rays, and cosmic rays. 
)
Diagrammatic representation of electromagnetic waves.
F waves
1. flutter w's; rapid sawtooth-edged atrial waves without isoelectric intervals between them; seen in the electrocardiogram in atrial flutter. Written also f w's .
2. f w's (1).
f waves
1. fibrillary w's; small, irregular, rapid deflections in the electrocardiogram in atrial fibrillation. Written also F w's.
2. F w's (1).
fibrillary waves f w's (1).
flutter waves F w's (1).
J wave a deflection occurring in the electrocardiogram between the QRS complex and the onset of the ST segment, occurring prominently in hypothermia and in hypocalcemia.
P wave a deflection in the electrocardiogram produced by excitation of the atria.
pulse wave the elevation of the pulse felt by the finger or shown graphically in a recording of pulse pressure.
Q wave in the QRS complex, the initial downward (negative) deflection, related to the initial phase of depolarization of the ventricular myocardium, the depolarization of the interventricular septum.
R wave the initial upward deflection of the QRS complex, following the Q wave in the normal electrocardiogram and representing early depolarization of the ventricles.
S wave a downward deflection of the QRS complex following the R wave in the normal electrocardiogram and representing late depolarization of the ventricles.
T wave the deflection of the normal electrocardiogram following the QRS complex; it represents repolarization or recovery of the ventricles.
Ta wave a small asymmetric wave, of opposite polarity to the P wave, representing atrial repolarization; together with the P wave it defines atrial systole.
theta waves brain waves in the electroencephalogram with a frequency of 4 to 7 per second, mainly seen in children and emotionally stressed adults.
U wave a potential undulation of unknown origin immediately following the T wave and often concealed by it; seen in the normal electrocardiogram and accentuated in tachyarrhythmias and electrolyte disturbances.
alpha waves
Rhythmic oscillation in electrical potential occurring in the cortex of the human brain when awake and at rest. The rate of oscillation is 8-13 Hz. Syn. alpha rhythm. See resting membrane potential.
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