Biological Rhythms

Question 1

Endogenous Pacemakers

Answer 1

-Endogenous pacemakers are internal bodily mechanisms which regulate biological rythms-facilitate biological changes within a cyclical fashion and act as an internal body clock, instructing the body when to sleep and rise and do other processes in synchronicity with the environmental day/night cycle.

Question 2

Biological Rhythms

Answer 2

Biological processes/changes which occur cyclically over a period of time, e.g 24 hours in order to facilitate certain functions like eating, sleeping, rising etc and to synchronise such processes with the environment for optimal functioning.

E.g, the sleep wake cycle is syncrhonised to the day/night cycle of the external environment ensuring optimal functioning.

Question 3

Endogenous Pacemaker: Suprachiasmatic nucleus

Answer 3

The suprachiasmatic nucleus or SCN is the endogenous pacemaker of the circadian rhythm, it produces and inhibits the release of melatonin instructing the body to sleep and rise in a cyclical fashion.

They are regulated by the exogenous zietgiber of light which acts as a cue, when light is detected on cells SCM inhibits the release of melatonin telling the body to wake up, when darkness is detected the SCM releases melatonin telling the body to sleep-synchronises the sleep/wake cycle with the day/night cycle for optimal function.

Question 4

Exogenous Zietgibers

Answer 4

External influences which act as cues for internal mechanisms to facilitate biological changes at the same time, regulates EP triggering them to occur and synchronising them to the environment for optimal functioning.

Question 5

Endogenous zietgiber: Light

Answer 5

-Cue in the sleep/wake cycle which triggers the SCM release and inhibition of melatonin synchronising the sleep wake cycle to the day/night cycle for optimal functioning

Question 6

Research support for EPs: Ralph

Answer 6

-Took the scn of abnormal hamsters with a circadian rhythm of 20 hours and put them into hamsters with a normal circadian rhythm of 24 hours, the hamsters also developed an abnormal ciradian rhythm, this shows that the SCN maintains and regulates the internal body clock and the circadian rhythm

-Low generalisability? hamsters have different brains to humans, cannot draw conclusions from animal studies but it could also be argued humans have an SCN and 24 hour circadian rhythm so the processes are the same

Question 7

Support for Ezs-Siffre

Answer 7

-Cave study, spent 6 months in a dark cave with no natural light, he only had an artificial light when he woke up- his circadian rhythm become abnormal when he emerged- 25-30 hours, this shows light acts as an EZ maintaining the 24 hour circadian rhythm with the day/night cycle as when light is removed the circadian rhythm becomes abnormal