Circadian Rhythm

Topics: Circadian rhythm, Melatonin, Pineal gland Pages: 2 (590 words) Published: March 3, 2013
Circadian rhythm

Although most people tend to think that manifestations of body function such as temperature and blood pressure are constant throughout the day, the fact is that many functions change in cyclic patterns – especially those that are affected by hormones, such as cortisol. These daily fluctuations, or circadian rhythms are fundamental to all organisms, from bacteria to humans. Circadian rhythms help coordinate and synchronize our internal body functions, as well as our interactions with the external world. The word circadian means around or approximately a day.

The circadian rhythms are internal mechanisms that operate on an approximately 24 hour cycle. It’s most important function is to regulate the sleep/wake cycle. It also regulate the frequency of eating and drinking, body temperature, secretion of hormones, volume of urination, and sensitivity to drugs.

A few interesting ‘times’ during the 24 hour cycle is: the bowel movements, fastest reaction time, best coordination, and then the most interesting the highest testosterone secretion? This is all controlled by a group of cells called the suprachiasmatic nucleus.

The suprachiasmatic nucleus or SCN is a part of the hypothalamus and the main control center of the circadian rhythms of sleep and temperature. It is located above the opt chiasm. Any damage to the SCN results in less consistent body rhythms that are no longer synchronized to environmental patterns of light and dark. It results in the complete absence of a regular sleep-wake rhythm.

The optic chiasm is the part of the brain where the optic nerves partially cross. The optic chiasm is located at the bottom of the brain immediately the hypothalamus. The SCN is a pair of distinct groups of cells located in the hypothalamus. The SCN receives information about illumination through the eyes. The retina of the eye contains photoreceptors, which are used for conventional vision.

But the retina also contains...
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