endogenous pacemakers and exogenous zeitgebers

Question 1

what are 2 examples of endogenous pacemakers?

Answer 1

1. supra-charismatic nucleus = light - optic nerve - SCN - pineal gland
2. pineal gland = increase melatonin (sleep)

Question 2

limitation of endogenous pacemakers (ignores)

Answer 2

SCN ignores other body clocks - some organs/cells act independently
- changed eating pattern of mice altered circadian rhythms of liver by 12 hours and SCN was unaffected

Question 3

limitation of endogenous pacemakers (influence)

Answer 3

studies never fully lack exogenous zeitgebers - siffre had a torch - so may influence endogenous pacemakers

Question 4

who did research into endogenous pacemakers?

Answer 4

ralph

Question 5

what was ralph’s procedure and findings?

Answer 5

• bred hamsters to have abnormal circadian rhythms
• some nerve cells from SCN were placed in normal hamsters
• normal hamsters displayed a circadian rhythm of 20 hours

Question 6

what are 2 examples of exogenous zeitgebers?

Answer 6

1. light
2. social cues

Question 7

who conducted research into exogenous zeitgebers?

Answer 7

campbell and murphy

Question 8

what was campbell and murphy’s procedure and findings?

Answer 8

• shone light pad of back of 15 pps knees
• adjusted their SWC
• detected by skin receptors

Question 9

limitation of exogenous zeitgebers (blind young man)

Answer 9

miles - studied boy, blind from birth, who had circadian rhythm of 24.9 and it stayed like this regardless of social cues

Question 10

limitation of exogenous zeitgebers (diff influence in diff environments)

Answer 10

northern hemisphere experience 24 hours of daylight in summer and little light in winter - SWC doesn’t shift

Question 11

strength of exogenous zeitgebers (research)

Answer 11

jet lag adjusted better outside - EP alone don’t control rhythms