GLOSSARY...
- biological clock---
- an internal timekeeping mechanism capable of driving
or coordinating a circadian rhythm.
- biological rhythm---
- self-sustained cyclic change in a physiological process or behavioral function of an organism that repeats at regular intervals.
- circadian---
- taken from Latin words meaning "around" and "day"
- circadian rhythm---
- a self-sustained biological rhythm which in an organism's natural
environment normally has a period of approximately 24 hours
- circannual---
- a biological rhythm with a period of about one year
- cyanobacteria---
- a type of bacteria within genus Synechococcus
- diurnal---
- performed in or belonging to the daytime; opposite of nocturnal
- eclosion---
- emergence of the adult insect from its pupal case
- endogenous---
- self-sustained rhythm generated within an organism
- entraining agent---
- an environmental time cue such as light that has the ability to reset
a biological clock
- euthermic---
- producing or creating heat or warmth
- exogenous---
- rhythm generated within or by an organism because of rhythmic environmental
cues that are external to the organism
- free running---
- natural self-sustained rhythm that exists in the absence of all
environmental cues. When a human is free running, his/her cycle appears to be
slightly longer than 24 hours.
- genome---
- the total genetic content of a cell
- heliotrope---
- one of several species of plants whose flowers or stem buds face east in
the morning, follow the movement of the sun during the day, and face west in
the evening
- homeotherm---
- organism whose internal body temperature is maintained at a relatively
constant temperature through the organism's metabolic activities; its body
temperature typically does not change in response to changes in environmental
temperature fluctuations; homeotherms were once called "warm-blooded"
- hypothalamus---
- small area of the brain near the top of the brain stem; control site of
behaviors such as feeding or drinking, temperature regulation, secretion of
hormones through its effect on the pituitary gland
- infradian---
- describes processes having periods much greater than 24 hours
- melatonin---
- a hormone secreted by the pineal gland used as a marker of circadian rhythmicity in humans
- period---
- the time that elapses before a rhuthm starts to repeat itself
- photoperiodism---
- the length of light in a light/dark cycle
- poikilotherm---
- organism whose internal body temperature varies with and remains close to
environmental temperature; poikilotherms were once called "cold-blooded"
- pulsatile---
- rhythmic regular movement
- sleep debt---
- a deficit in normal sleep time
- tau---
- this term refers to an organism's period length
- temporal---
- of or relating to time
- ultradian---
- describes processes having periods much less than 24 hours
- zeitgeber---
- taken from German words meaning "time givers"; an environmental time cue
such as sunlight, food, noise, or social interaction that usually helps reset
the biological clock to a 24-hour day
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