Chapter 10 (Biological Rhythms and Sleep) Flashcards
biological rhythm
A regular fluctuation in any living processes.
circadian rhythm
A pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period.
ultradian
Referring to a rhythmic biological event whose period is shorter than that of a circadian rhythm, usually from several minutes to several hours long.
infradian
Referring to a rhythmic biological event whose period is longer than that of a circadian rhythm–that is, longer than a day.
diurnal
Active during the light periods of the daily cycle.
nocturnal
Active during the dark periods of the daily cycle.
free-running
Referring to a rhythm of behavior shown by an animal deprived of external cues about time of day.
period
The interval of time between two similar points of successive cycles, such as sunset to sunset.
phase shift
A shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus.
entrainment
The process of synchronizing a biological rhythm to an environmental stimulus.
zeitgeber
Literally “time-giver” (in German). The stimulus (usually the light-dark cycle) that entrains circadian rhythms.
suprachiasmatic nucleus (SCN)
A small region of the hypothalamus above the optic chiasm that is the location of a circadian cloth.
melatonin
An amine hormone that is secreted by the pineal gland at night, thereby signaling day length to the brain.
retinohypothalamic pathway
The route by which retinal ganglion cells send their axons to the suprachiasmatic nuclei.
melanopsin
A photopigment found within particular retinal ganglion cells that projects to the suprachiasmatic nucleus.
electroencephalography (EEG)
The recording and study of gross electrical activity of the brain via large electrodes placed on the scalp.
slow-wave sleep (SWS)
Also called non-REM sleep. Sleep, divided into stages 1-3, that is defined by the presence of slow-wave EEG activity.
rapid-eye-movement (REM) sleep
Also called paradoxical sleep. A stage of sleep characterized by small-amplitude, fast-EEG waves, no postural tension, and rapid eye movements.
desynchronized EEG
Also called beta activity. A pattern of EEG activity comprising a mix of many different high frequencies with low amplitude.
alpha rhythm
A brain potential of 8-12 hertz that occurs during relaxed wakefulness.
vertex spike
A sharp-wave EEG pattern that is seen during stage 1 sleep.
stage 1 sleep
The initial stage of slow-wave sleep, which is characterized by small-amplitude EEG waves of irregular frequency, slow heart rate, and reduced muscle tension.
stage 2 sleep
A stage of slow-wave sleep that is defined by bursts of regular 14- to 18-hertz EEG waves called sleep spindles.
sleep spindle
A characteristic 14- to 18-hertz wave in the EEG of a person said to be in stage 2 sleep.
K complex
A sharp, negative EEG potential that is seen in stage 2 sleep.
stage 3
A stage of slow-wave sleep that is defined by the presence of large amplitude, slow delta waves.
delta wave
The slowest type of EEG wave, characteristic of stage 3 sleep.
nightmare
A long, frightening dream that awakens the sleeper from REM sleep.
night terror
A sudden arousal from stage 3 sleep that is marked by intense fear and autonomic activation.
sleep deprivation
The partial or total prevention of sleep.
sleep recovery
The process of sleeping more than normally after a period of sleep deprivation, as though in compensation.
ecological niche
The unique assortment of environmental opportunities and challenges to which each organism is adopted.
isolated brain
An experimental preparation in which an animal’s brainstem has been separated from the spinal cord by a cut below the medulla.
isolated forebrain
An experimental preparation in which an animal’s nervous system has been cut in the upper midbrain, dividing the forebrain from the brainstem.
basal forebrain
A ventral region in the forebrain that has been implicated in sleep.
tuberomammillary nucleus
A region of the basal hypothalamus, near the pituitary stalk, that plays a role in generating slow-wave sleep.
general anesthetic
A drug that renders an individual unconscious.
reticular formation
Also called reticular activating system. An extensive region of the brainstem (extending from the medulla through the thalamus) that is involved in arousal (waking).
locus coeruleus
A small nucleus in the brainstem whose neurons produce norepinephrine and modulate large areas of the forebrain.
narcolepsy
A disorder that involves frequent, intense episodes of sleep, which last from 5 to 30 minutes and can occur anytime during the usual waking hours.
cataplexy
Sudden loss of muscle tone, leading to collapse of the body without loss of consciousness. Cataplexy is sometimes a common component of narcoleptic attacks.
hypocretin
Also called orexin. A neuropeptide produced in the hypothalamus that is involved in switching between sleep states, in narcolepsy, and in the control of appetite.
sleep paralysis
A state, during the transition to or from sleep, in which the ability to move or talk is temporarily lost.
sleep enuresis
Bed-wetting.
somnambulism
Sleepwalking.
REM behavior disorder (RBD)
A sleep disorder in which a person physically acts out a dream.
sleep-onset insomnia
Difficulty in falling asleep.
sleep-maintenance insomnia
Difficulty in staying asleep.
sleep apnea
A sleep disorder in which respiration slows or stops periodically, waking the patient. Excessive daytime sleepiness results from the frequent nocturnal awakening.
sudden infant death syndrome (SIDS)
Also called crib death. The sudden, unexpected death of an apparently healthy human infant who simply stops breathing, usually during sleep.
sleep state misperception
Commonly, a person’s perception that he has not been asleep when in fact he has. It typically occurs at the start of a sleep episode.
