endogenous pacemakers

Question 1

what are endogenous pacemakers

Answer 1

internal body clocks that regulate many of our biological rhythms, such as the influence of the SCN on the sleep wake cycle or hormones on the menstrual cycle

Question 2

what is an example of an endogenous pacemaker

Answer 2

the suprachiasmatic nucleus

Question 3

outline the SCN

Answer 3

• a tiny bundle of nerve cells located in the hypothalamus in each hemisphere of the brain
• its influential in maintaining circadian rhythms such as the sleep wake cycle
• nerve fibres in the SCN are connected to the eye so the SCN receives info about light
• continues when eyes are closed as light penetrates through eyelids
• enables our biological clock to adjust to changing patterns of light when we are asleep

Question 4

outline DeCoursey’s research supporting the SCN

Answer 4

• destroyed SCN connections in the brains of 30 chipmunks
• they were then returned to natural environment and observed for 80
• observations showed that their sleep wake cycle had disappeared
• at the end a significant portion had also been killed which is probably because they were awake and vulnerable when they should’ve been asleep

Question 5

outline Morgans research supporting the SCN

Answer 5

• bred a strain of hamsters so that they had abnormal circadian rhythms of 20 instead of 24 hours
• SCN neurons from these abnormal hamster were then transplanted into the brains of normal hamsters
• the normal hamsters then displayed the same abnormal circadian rhythm of 20 hours showing that the transplanted SCN had imposed its pattern onto the recipients brains

Question 6

what is a limitation of Morgans research (animals)

Answer 6

in the case of Morgans research it is not certain that transplanting SCN neurone into human brains would have the same effect since human brains are much more sophisticated compared to hamsters. this means that any researchers drawn from this research must be taken with caution.

Question 7

what is a limitation of DeCourseys research (ethics)

Answer 7

ethical issues- can be regarded as unethical. it is evident that the chipmunks they used were exposed to considerable risk and subsequent harm when they were returned to their natural environment. it is a matter of debate if the significance of their findings is of sufficient value to justify the aversive procedures they employed

Question 8

discuss the pineal gland as support for endogenous pacemakers

Answer 8

• receives information relating to day length and light from the SCN
• during the night the pineal gland increases production of melatonin- a chemical which induces sleep, the production of which is inhibited during the day