endogenous pacemakers and exogenous zeitgebers

Question 1

what are endogenous pacemakers sometimes referred to as ?

Answer 1

internal biological clocks

Question 2

what do exogenous zeitgebers do ?

Answer 2

• they resets its clock everyday to maintain its coordination with the external world

Question 3

what is an example of an endogenous pacemaker that influences the sleep/wake cycle ?

Answer 3

the SCN which lies in the hypothalamus

Question 4

what is the SCN’s function ?

Answer 4

it maintains circadian rhythms such as the sleep/wake cycle

Question 5

how does the SCN enable the biological clock to adjust to changing light ?

Answer 5

the SCN receives info about the light directly from the optic chiasm and this continues even when our eyes are closed

Question 6

what is the role of the pineal gland ?

Answer 6

• the SCN passes info on day length and light that it receives to the pineal gland
• during the night, it increases production of melatonin

Question 7

Describe research carried out by Ralph (1990)

Answer 7

• bred ‘mutant’ hamsters with a 20 hour sleep/wake cycle
• when SCN cells from the foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters, the cycle of the 2nd group defaulted to 20 hours

Question 8

AO3 of Ralph
- ethics in animal studies

Answer 8

• animals were exposed to considerable harm

Question 9

AO3 of Ralph
use of animals

Answer 9

• problems with generalisations

Question 10

what is an example of an exogenous zeitgeber that influences the sleep/wake cycle ?

Answer 10

• light and social cues
• social cues : when someone tells you that they are tired

Question 11

what can light reset ?

Answer 11

• the body’s main endogenous pacemaker, the SCN

Question 12

what kind of effect does light have on the body ?

Answer 12

• light has an indirect influence on key processes in the body that control functions such as hormone secretion and blood circulation

Question 13

How do social cues work on babies and their sleep/wake cycle ?

Answer 13

• infants rely on the same sleep/wale cycle as the rest of the family
• in infants, the initial cycle is pretty much random
• at about 6 weeks of age, the circadian rhythms begin and by about 16 weeks, most babies are entrained
• these imposed schedules are likely to be a key influence including adult determined mealtimes

Question 14

Describe research carried out by Campbell and Murphy

Answer 14

• 15ps were woken at various times and a light pas was shone at the back of their knees
• researchers managed to produce a deviation in the ps usual cycle of up to 3 hours in some cases

Question 15

what did the results of Campbell and Murphy’s research suggest ?

Answer 15

• suggests light is a powerful exogenous zeitgeber

Question 16

What did Campbell and Murphy demonstrate ?

Answer 16

• they demonstrated that light may be detected by skin receptor sites even when the same info is not received by the eyes

Question 17

AO3 Campbell + Murphy
methodological issue

Answer 17

• other psychologists have been critical of the manner in which the study was conducted and they may have suggested that there may be some limited light exposure to the ps eyes

Question 18

AO3 Campbell + Murphy
major confounding variables

Answer 18

• isolating 1 exogenous zeitgeber in this way does not give us insight into the many other zeitgeber that influence the sleep/wake cycle, and the extent to which these may interact