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psychology > biological rhythms, endogenous pacemakers and exogenous zeitgebers > Flashcards

biological rhythms, endogenous pacemakers and exogenous zeitgebers Flashcards

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1
Q

what is a biological rhythm?

A

a distinct pattern of change in body activities that conform to cyclical time periods

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2
Q

what 2 things are all biological rhythms governed by?

A

endogenous pacemakers

exogenous zeitgebers

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3
Q

how long do circadian rhythms last for?

A

24 hours

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4
Q

what are 2 examples of circadian rhythms?

A

the sleep/wake cycle

core body temperature

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5
Q

what is the important exogenous zeitgeber that makes us feel drowsy at night and alert during the day (the sleep/wake cycle)?

A

daylight

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6
Q

who studied whether endogenous pacemakers may have an effect on the sleep/wake cycle?

A

Siffre

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7
Q

how did siffre study the effects of endogenous pacemakers on the sleep/wake cycle and what were the results?

A

he spent extended periods of time inside a cave, deprived of natural light and sounds
he found his ‘free running’ biological rhythm settled to one that was just beyond 24 hours (around 25 hours), though he continued to fall asleep and wake up on a regular schedule

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8
Q

who found similar results to Siffre’s cave study?

A

Aschoff and Wever

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9
Q

what do Siffre and Aschoff and Wever’s results suggest?

A

the ‘natural’ sleep/wave cycle may be slightly longer than 24 hours, but it is entrained by exogenous zeitgebers associated with our 24 hour day (e.g. meal times, number of daylight hours)

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10
Q

why does research into the sleep/wake cycle have economic implications?

A

it shows us how to best manage worker productivity
shift workers are more likely to have poorer health and night workers are more likely to make more mistakes/have more accidents

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11
Q

how has research into circadian rhythms helped with drug treatments?

A

because circadian rhythms co-ordinate body functions such as heart rate, digestion and hormone levels, it has an effect on pharmacokinetics (the actions of drugs on the body and how well they are absorbed and distributed)

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12
Q

why are the studies into circadian rhythms usually ungeneralisable?

A

small-scale studies and case studies are used- unrepresentative of the general population

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13
Q

what did Siffre find as he got older? what implications does this have?

A

at the age of 60 his internal clock ticked much slower than it did when he was young.
even when the same person is involved, there are factors which may prevent general conclusions being drawn

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14
Q

what is one major issue in Siffre’s study which may have effected his results?

A

the use of artificial light- which he turned on when he woke up and turned off when he went to sleep

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15
Q

what did Czeisler et al find in terms of individual differences in circadian rhythms?

A

individual’s sleep/wake cycle can vary from 13 to 65 hours

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16
Q

what are infradian rhythms and 2 examples?

A

a type of biological rhythm with a frequency of less than one cycle in 24 hours
menstruation and seasonal effective disorder

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17
Q

what are ultradian rhythms?

what is an example?

A

a type of biological rhythm with a frequency of more than one cycle in 24 hours
sleep stages

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18
Q

what is the menstrual cycle (an infradian rhythm) governed by?

A

monthly changes in hormone levels which regulate ovulation

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19
Q

how long (approximately) is the menstrual cycle?

A

28 days

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20
Q

what happens in the menstrual cycle?

A

rising levels of oestrogen cause the ovary to develop an egg and release it (ovulation). after ovulation, the hormone progesterone helps the womb lining to grow thicker, readying the body for pregnancy. if pregnancy does not occur, the egg is absorbed into the body, and the womb lining comes away and leaves the body (the menstrual flow)

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21
Q

is the menstrual cycle an endogenous or exogenous system?

A

endogenous

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22
Q

what did McClintock and Stern find regarding menstrual cycles?

A

menstrual cycles may synchronize as a result of the influence of other female’s pheromones
exogenous factors can effect the timing of the menstrual cycle

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23
Q

what was McClintock’s procedure into menstrual cycle synchronization?

A

29 women with irregular periods
samples of pheromones were taken from 9 women who were at different stages of the menstrual cycle via a cotton pad on their armpit
pads treated with alcohol and frozen to be placed on the upper lip of the other women
on day one, pads from the start of the cycle were applied to the other 20 women, on day 2 pads from the second day were applied etc.

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24
Q

what were the findings from McClintock’s study?

A

68% of women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor’

25
Q

what are the main symptoms of seasonal affective disorder (SAD)?

A

persistent low moods and a general lack of activity and interest in life

26
Q

when is SAD triggered and why?

A

in the winter months

because the number of daylight hours are shorter

27
Q

what is the specific type of rhythm that SAD can be classed as other than infradian and why?

A

circannual rhythm

because it is a yearly cycle

28
Q

why can SAD also be referred to as a circadian rhythm?

A

as SAD may be due to the disruption of the sleep/wake cycle, due to the prolonged daily darkness during winter

29
Q

what have psychologists hypothesised is the cause of SAD?

A

during the night, the pineal gland secretes melatonin until dawn when there is an increase in light. during winter, the lack of light in the morning means this secretion process continues for longer. this is thought to have a knock on effect on the production of serotonin in the brain- a chemical that has been linked to the onset of depressive symptoms

30
Q

how many stages of sleep are there and how long does it take to get through the stages?

A

5 stages

roughly 90 minutes

31
Q

what is each stage of the sleep cycle characterised by?

A

different level of brainwave activity

32
Q

how can these sleep stages be monitored?

A

using an EEG

33
Q

what is stage 1 and 2 called and what waves are associated with them?

A

light sleep

theta waves

34
Q

what is stage 3 and 4 called and what waves are associated with them?

A

deep sleep/slow wave sleep

delta waves

35
Q

what is stage 5 and what happens in it?

A

REM (rapid eye movement) sleep

the body is paralysed yet brain activity speeds up significantly

36
Q

what is the evolutionary basis of the menstrual cycle?

A

for our ancestors it may have been advantageous for females to menstruate together and therefore fall pregnant around the same time, and could look after the children collectively

37
Q

why has the validity of the evolutionary basis of the menstrual cycle been questioned and according to who?

A

the avoidance of synchrony would be the most adaptive evolutionary strategy according to Schank

38
Q

what are extraneous variables that may have effected the results of McClintock’s study?

A

stress, changes in diet, exercise, etc.

39
Q

who failed to find any evidence of menstrual synchrony in all female samples?

A

Trevathan et al

40
Q

what did Dement and Kleitman find in their study on the sleep stages?

A

REM sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, and participants woken during dreaming reported very accurate recall of their dreams

41
Q

does Dement and Kleitman’s study support the sleep cycle?

A

yes

42
Q

what has research into SAD helped develop?

A

a treatment- phototherapy

43
Q

what is the suprachiasmatic nucleus (SCN) and where is it located?

A

a tiny bundle of nerve cells

located in the hypothalamus in each hemisphere of the brain

44
Q

is the SCN a primary endogenous pacemaker?

A

yes

45
Q

what type of rhythm is the SCN influential in maintaining?

A

circadian

46
Q

how does the SCN receive information about light?

what does this enable our biological clock to do?

A

nerve fibres connected to the eye cross in an area called the optic chiasm on their way to the visual area of the cerebal cortex. the SCN lies just above the optic chiasm. this is how it receives information about light, which continues even when our eyes are closed, enabling the biological clock to adjust to changing patterns of daylight whilst we are asleep

47
Q

what did DeCoursey et al. do to chipmunks in their study of the sleep/wake cycle?

A

destroyed the SCN in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80 days. the sleep/wake cycle of the chipmunks completely disappeared and by the end of the study a significant amount of the chipmunks had been killed by predators

48
Q

what did Ralph et al do in their study using hamsters?

A

they bred ‘mutant’ hamsters with a 20 hour sleep/wake cycles. when the SCN cells from the foetal tissue of mutant hamsters were transplanted into the brain of normal hamsters, the cycles of the second group defaulted to 20 hours

49
Q

what do both DeCoursey et al. and Ralph et al’s studies emphasise in terms of the SCN?

A

emphasise the role of the SCN in establishing and maintaining the circadian sleep/wake cycle

50
Q

what is the structure of the pineal gland and where is it located?

A

a pea-like structure

just behind the hypothalamus

51
Q

where does the SCN pass the information on day length and light that it receives?

A

to the pineal gland

52
Q

what does the pineal gland increase production of during the night and what does it do?

A

melatonin

its a chemical that induces sleep

53
Q

what has melatonin been suggested to have a casual link to (infradian rhythm)?

A

SAD

54
Q

what are endogenous pacemakers?

A

internal body clocks that regulate many of our biological rhythms

55
Q

what are exogenous zeitgebers?

A

external cues that may affect or entrain our biological rhythms

56
Q

what are the 2 main exogenous zeitgebers?

A

light

social cues

57
Q

what main endogenous pacemaker can light reset?

A

the SCN

58
Q

what key processes in the body can light have an indirect influence on?

A

hormone secretion

blood circulation

59
Q

what did Campbell and Murphy demonstrate in their study of how light effects the sleep/wake cycle and how did they do it?

A

they demonstrated that light may be detected by skin receptor sites on the body even when the same information is not detected by the eyes
15 participants were woken up at various times and a light pad was shone on the back of their knees. the researchers managed to produce a deviation in the participant’s sleep/wake cycle by up to 3 hours

psychology (6 decks)

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