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The Biological Clock Notes

This is a sample of our (approximately) 3 page long The Biological Clock notes, which we sell as part of the Psychology Notes collection, a B package written at York College in 2015 that contains (approximately) 157 pages of notes across 48 different documents.

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The Biological Clock Revision

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The biological clock Thought mainly to be an endogenous (internal) mechanism/

Our internal rhythms are thought to be generated by protein synthesis within the SCN (suprachiasmatic nucleus) in the hypothalamus - protein is produced for a period of hours until it reaches a level that inhibits further production - over the next few hours the protein level gradually falls, when it drops to a certain threshold then production of the protein restarts - this generates an internal (endogenous) biological rhythm of between 24 to 25 hours in humans This endogenous rhythm is regulated to keep it in line with our environmental rhythms by an exogenous (external) mechanism/
zeitgebers o SCN has a nerve input (optic chiasm) directly from the retina of the eye, so they are kept informed about the zeitgebers of light and darkness o In darkness, this information is transmitted to the pineal gland which manufactures melatonin, a hormone which stimulates the production of serotonin in the raphe nucleus - this hormone causes reduced levels of arousal, so induces sleep o When light enters through the eyes, it stimulates the SCN to produce an inhibiting factor (probably a protein) - this inhibits the production of melatonin by the pineal gland and so maintains arousal levels, keeping you alert and awake

Exogenous zeitgebers:

Light Temperature Food intake Shift work Noise/ unwanted sound - controlled by legislation Medicine - hard to control/ add something to make them sleep/
change medication Caffeine - age restrictions Travel


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