The effect of Endogenous Pacemakers

Question 1

What is the role of the suprachiasmatic nucleus (SCN)?

Answer 1

Relays information to the pineal gland about the light levels to elicit the release of melatonin.

Question 2

What is the role of the optic chiasma?

Answer 2

Contains melanopsin that is sensitive to light and sends information to the suprachiasmatic nucleus.

Question 3

What does melatonin do to a human when produced?

Answer 3

Makes them feel tired.

Question 4

Give some examples of exogenous zeitgebers.

Answer 4

Light, temperate, meal times, social activities.

Question 5

Where else on the body is sensitive to light, according to Murphy and Campbell.

Answer 5

Light shone on the back of the knees affected the circadian rhythm of the sleep/wake cycle.

Question 6

Give some advantages to the role of exogenous/endogenous zeitgebers on the sleep-wake cycle.

Answer 6

+Supporting evidence for the role of the SCN. Ralph found that when cells were transferred from abnormal hamsters to normal hamsters, their circadian rhythm was also shortened. The SCN had imposed its pattern on the hamsters

+Supporting evidence for the influence of exogenous zeitgebers from Miles. Those who were completely blind had a highly abnormal circadian rhythm. This demonstrates the importance of exogenous zeitgebers.

Question 7

Give some disadvantages of exogenous and endogenous zeitgebers on the sleep wake cycle.

Answer 7

-Ralph’s study was an animal study which means there is difficulty extrapolating findings to human populations. Also, both studies are ethically questionable

-Miles’ study was a case study which means it has low population validity. However, it provides great detail about one individual.