biological rhythms : circaidian rhythms ao1

Question 1

All living things have …

Answer 1

Biological rhythms

Question 2

Define endogenous pacemakers

Answer 2

Internal body clocks that regulate biological rhythms such as regular times of sleep linked to levels of light
Eg suprachiasmatic nucleus and pineal gland

Question 3

Ralph et al 1990 procedure

Answer 3

Took the SCN (superchiasmatic nuclues) out of genetically abnormal hamsters which only had a circadian rhythm of 20h and transplanted them into normal rats who had a 24h cycle

Question 4

Findings of Ralph et al 1990

Answer 4

They found the rats cycle shortened to 20h showing that the SCN is determining the length of the cycle

Question 5

Morgan 1995

Answer 5

Removal of SCN from hamsters completely and their sleep wake cycle disappeared

Question 6

How does SCN WORK

Answer 6

Neurons within it spontaneously synchronise with eachother so that target neurons in sites elsewhere in the body receive correctly time coordinating signals

Question 7

Define exogenous zeitgebers

Answer 7

An environmental cue such as light that helps to regulate the biological clock in an organism

Question 8

2 Types of exogenous zeitgebers

Answer 8

Light
Social cues

Question 9

Explain how exogenous zeitgebers work in terms of light

Answer 9

Light can reset the bodies main pace maker SCN
Light also has an indirect influence on key processes in the body that control hormone secretion

Question 10

Who and when did study on light as a exogenous zeitgebers

Answer 10

Campbell and Murphy 1998

Question 11

Define Entrainment

Answer 11

An adjustment of the body clock in line with the environment

Question 12

Campbell and Murphy 998 procedure

Answer 12

Demonstrated that light may be detected by skin receptor sites on the body even when the same info is not received by the eyes
15 ppts were woken at various times abd a light pad was shone on the back of their knees

Question 13

Campbell and Murphy 1988 findings and conclusions

Answer 13

Researchers managed to produce a deviation in the ppts usual sleep wake cycle of up to 3h in some cases
Suggests light is a powerful exogenous zeitgebers that dont have to rely on the eyes only to exert influence on the brain

Question 14

Exogenous zeitgebers - social cues

Answer 14

Infants sleep wake cycle is random at first
6 weeks - circadian rhythms begin
16 weeks entertained rhythms