The Biological Clock

HideShow resource information

The Biological/body Clock (your endogenous pacemaker) – how does it work?

An endogenous (internal) mechanism

l  Thought to be generated by protein synthesis within the Supra Chiasmatic Nuclei (SCN). It’s in the hypothalamus.

l  How? …

l  Protein is produced for a number of hours until it reaches a level that inhibits further production. 

l  Then the level gradually falls, when it reaches a  ‘threshold’ level then production of the protein re-starts. 

l  This generates an internal (endogenous) biological rhythm – in humans of between 24 ½ and 25 hours.  

l  This endogenous rhythm is regulated to keep it in line with our environmental rhythms by an exogenous mechanism:

l  SCN have a nerve input directly from the retina of the eye, so they are kept informed about the zeitgebers of light and darkness.

l  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 and so induces sleep.



No comments have yet been made

Similar Psychology resources:

See all Psychology resources »See all Sleep resources »