Chapter 10 Flashcards
Circadian Rhythm
Pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period.
Ultradian
Period shorter than a day, usually several minutes to several hours long
Infradian
Period longer than a day
Free-running
Rhythm of behavior shown by an animal deprived of external cues about time of day
Period
Interval between two similar points of successive cycles, such as sunset to sunset
Phase Shift
Shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus
Entrainment
The process of synchronizing environmental stimulus
Zeitgeber
“time-giver” The stimulus (usually the light-dark cycle) that entrains circadian rhythms
Suprachiasmatic Nucleus (SCN)
Small region of hypothalamus above the optic chiasm that is the location of a circadian clock.
Melatonin
Amine hormone that is secreted by the pineal gland at night, signaling day length to the brain.
Retinohypothalamic pathway
The route by which retinal ganglion cells that project to the suprachiasmatic nucleus
Melanopsin
Photopigment found in those retinal ganglion cells that project to the suprachiasmatic nucleus.
Rapid-eye-movement (REM) sleep
“paradoxical sleep” Small-amplitude, fast EEG waves, no postural tension and rapid eye movements.
non-REM sleep
3 stages,, defined by presence of distinctive EEG activity
Desynchronized EEG
“beta activity” pattern of EEG comprised of a mix of many different high and low EEG’s
Alpha Rhythm
Brain potential of 8-12 hertz, occurs during relaxed wakefulness
Vertex Spike
Sharp-wave EEG pattern seen during stage 1 sleep
Stage 1 Sleep
Initial stage of non-REM sleep, small amplitude EEG waves of irregular frequency, shlow heart rate, reduced muscle tension
Stage 2 Sleep
Bursts of regular 14-18 hertz EEG waves called sleep spindles
Sleep Spindle
14-18 Hz EEG waves (characteristic to stage 2)
K complex
Sharp negative EEG potential seen in sleep stage 2
Stage 3 Sleep
“slow wave sleep” (SWS) Stage of non-REM sleep defined by presence of large amplitude, show delta waves
Delta Wave
Slowest type of EEG wave. (characteristic to stage 3)
Nightmare
Long, frightening dream that awakens sleeper from REM sleep
Night Terror
Sudden arousal from stage 3 sleep, marked by intense fear and autonomic activation
