ENDO PM + EXO ZG

Question 1

ENDOGENOUS PACEMAKER AO1

Answer 1

→ internal body clock

→superchiasmatic nucleus (SCN), in hypothalamus is the main endogenous pacemaker. →SCN also receives info about light levels (exogenous zeitgeber) from the optic nerve, which sets the circadian rhythm so that it is in synchronization w/ the outside world.

→ SNC sends signals to the pineal gland, which leads to an incr production of melatonin at night, helping to induce sleep. The SCN and pineal glands work together as endogenous pacemakers; however, their activity is responsive to the external cue of light.

Question 2

EXOGENOUS ZEITGEBER AO1

Answer 2

→exogenous zeitgebers influence biological rhythms: these can be described as environmental events responsible for resetting the biological clock of an organism.

→include social cues e.g, meal times, but the most important zeitgeber is light, which is responsible for resetting the body clock each day, keeping it on a 24 hr cycle.

→ SNC contains receptors that are sensitive to light + this external cue is used to synchronise body’s internal organs + glands. Melanopsin - protein in the eye, is sensitive to light + carries the signals to SCN to set the 24 hr daily body cycle.

Question 3

research related to ENDOGENOUS PACEMAKERS

Answer 3

RALPH: removed SCN out of abnormal rats whose circadian rhythm = 20hrs, + transplanted them to notmal rats. The normal rats circadian rhythm shortened to 24hrs. TS significance of the SCN and how endogenous pacemakers are important for biological circadian rhythms.
BUT, → used hamsters. Humans would respond differently to manipulations of their biological rhythms, not only because we are different biologically, but also because of the vast differences between environmental contexts. This makes research carried out on other animals unable to explain the role of endo pacemakers in the biological processes of humans.

Question 4

research related to EXOGENOUS ZEITGEBERS

Answer 4

SKENE + ARENDT: claimed the majority of blind people who still have some light perception have normal circadian rhythms whereas those without any light perception show abnormal circadian rhythms. TS importance of exo zeitgebers as a biological mechanism + their impact on biological circadian rhythms. 


SIFFRE: returned from an underground stay w/ no clocks or light, he believed the date to be a month earlier than it was. TS his 24-hour sleep- wake cycle was incr by lack of external cues, making him believe one day was longer than it was. TS impact of exo zeitgebers on bodily rhythms.

Question 5

IDA

Answer 5

REDCUTIONISM vs HOLISM
Biologically reductionist. e.g, behaviourist approach suggests bodily rhythms are influenced by other people + social norms, i.e. sleep occurs when it is dark as that is the social norm + it wouldn’t be socially acceptable for a person to conduct their daily routines during the night. The research discussed here could be criticised for being reductionist as it only considers a singular biological mechanism + fails to consider the other widely divergent viewpoints.