Biological rhythms

Question 1

Describe Campbell+Murphy (1998) study about sleep-wake cycle?

Answer 1

-woke 15 participants at various times throughout the night and shone a light on the back of their knees
-was found that a deviation in their sleep-wake cycle of up to 3 hours occurred as a result
-suggests we have light detecting receptors in other parts of our body
-person might have just seen the light
-study lacked control
-when it was replicated they did not get the same results

Question 2

Describe Ralph’s (1990) study about muta hamsters?

Answer 2

-mutant hamsters with an abnormal circadian rhythm of 20 hours instead of 24
-mutant SCN’s were transplanted into ‘normal’ hamsters brains
-normal hamsters then displayed the same 20 hour rhythm as mutant hamsters did
-transplantation of other parts of the brain had no effect
-may not generalise to humans (although it is logical that it would play the same function as we both have an SCN)
-scientific and well controlled
-unethical

Question 3

What is a circadian rhythm?

Answer 3

Lasts 24hours, cycle length is one day
Eg sleep-wake cycle

Question 4

What is meant by an infradian rhythm?

Answer 4

Lasts longer than 24 hours
Eg hibernation, seasonal affective disorder

Question 5

What is meant by an ultradian rhythm?

Answer 5

Last less than 24 hours
Eg sleep, heartbeat, blinking, eating, smoking

Question 6

Describe Michel Siffre (1962) study of an infradian rhythm?

Answer 6

-2+7 months in a cave
-maintained a regular sleep-wake cycle, therefore there must be something internal controlling it- internal body clock-SCN
-his sleep schedule extended to 25 hours-that means that we need external cues to remain synchronised with our 24hour day
-research method - case study
- male individual and his biological rhythms may not generalise to females

Question 7

Explain the difference between infradian and ultradian rhythms?

Answer 7

• infradian last longer than 24 hours eg menstrual cycle
  Ultradian last less than 24 hours eg blinking

Question 8

Outline the difference between endogenous pacemakers and exogenous zeitgebers?

Answer 8

• endogenous pacemakers are internal biological clocks that regulate rhythms eg hormones, brain structure
  -exogenous zeitgebers are external cues, like light and lifestyle, that influence these rhythms

Question 9

What is a biological rhythm?

Answer 9

A pattern of behaviour or a process which repeats on a regular basis over a specific period of time