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Circadian Rhythm: Three Major Components

Circadian rhythms are physical, mental, and behavioral changes that follow a roughly 24-hour cycle in response to light and darkness. They are controlled by the suprachiasmatic nucleus, a group of brain cells in the hypothalamus that acts as the central oscillator. The suprachiasmatic nucleus coordinates three major components - a central oscillator, input pathways that are influenced by temperature and light intensity, and output pathways that synchronize the clock to 24 hours through external cues like light.

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Arjun K V
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35 views5 pages

Circadian Rhythm: Three Major Components

Circadian rhythms are physical, mental, and behavioral changes that follow a roughly 24-hour cycle in response to light and darkness. They are controlled by the suprachiasmatic nucleus, a group of brain cells in the hypothalamus that acts as the central oscillator. The suprachiasmatic nucleus coordinates three major components - a central oscillator, input pathways that are influenced by temperature and light intensity, and output pathways that synchronize the clock to 24 hours through external cues like light.

Uploaded by

Arjun K V
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Circadian

rhythm
● Circadian rhythms are
physical, mental and
behavioural changes
that follow a roughly
24-hour cycle,
responding primarily to
light and darkness in an
organism’s
environment.
Three major
components
i. A central oscillator
ii. A series of input Variations in temperature and light
pathways intensity can influence circadian rhythm.
iii. A series of output
pathways
http://www.nigms.nih.gov/Education/Factsheet_CircadianRhythms.htm
Suprachiasmatic
nucleus
●The suprachiasmatic
nucleus (SCN) is a small
group of brain cells
(about 20,000) located in
the hypothalamus that
controls the circadian
cycle.
●The SCN clock is

autonomous, and when


deprived of external cues
it runs at an intrinsically
determined period (±24
h).
●To be synchronized to http://healthysleep.med.harvard.edu/image/200
24 h, the SCN clock is
reset by external cues

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