Biological Rhythms Flashcards

Question

How are the 2 endogenous pacemaker makers affected by exogenous zeitgebers

Answer 1

- SCN is reset every morning by light onset. The visual receptors in the retina part of the eye receive light signal and activate the retinohypalamic tract pathway - this pathway alertness the SCN and pineal gland affecting melatonin production Daylight reduces the release of melatonin and darkness leads to a radial increase in

Answer 2

I: evidence from human studies to support the role of internal endogenous pacemakers in the sleep wake cycle E: in Siffre’s study he spent 179 days in total isolation in a a cave, without access to any EZ such as sound,clocks,daylight. At first his sleep-wake cycle was errratic but settled down to around a 25-30 hour cycle C: sleep wake cycle is largely controlled by EP such as thre SCN and pineal gland but it is entrained by EZ associated with out 24 hour day

Answer 3

I: evidence from animals studies to support the role of internal endogenous pacemakers in the sleep wake cycle E: mutant hamsters were selectively bred to have a 20 hour sleep-wake cycle. SCN cells from foetal tissue of these hamsters were then removed and transplanted into brains of hamsters with normal sleep wake cycles The normal hamsters sleep wake cycle began to alter and changed to the 20 hour sleep wake cycle of the donor mutant hamsters C:findings add the the validity of the sleep wake cycle being largely controlled by endogenous pacemakers by showing the length of the cycle was dependent on the SCN

Answer 4

I: difficult to make generalisations from research supporting endogenous pacemakers affecting the control of the sleep wake cycle E E: in siffres study only one individual had been studied. Individual factors prevent the findings being generalised to the target population and the findings are then unrepresentative of everybody’s circadian rhythm. Unclear of what effect artificial light in the cave had on the cycle difficult to extrapolate to humans from animals as we may have different physiological structures C: difficult to draw conclusions from research due to small sample sizes in human studies and use on animal research

Answer 5

I: evidence supporting the interaction of EP’s and EZ’s E: jet lag occurs when crossing time zones and the body clock is on a different ‘time’ to the local environment. Melatonin is therefore released during the day this results in effects such as drowsiness C: findings add to the validity of the theory that endogenous pacemakers and exogenous zeitgibers interact, by showing that when they are desynchronised, there are severe and physiological effects

Answer 6

Consists of different stages which we pass through in more than one cycle in a night 5 stages of sleep Each stage lasts a different amount of time and is characterised by ey features and brain wave activity

Answer 7

- basic rest activity cycle (BRAC)

Answer 8

- a period of alterness, followed by a spell of fatigue - this occurs very 90 minutes throughout the day - in the first half we feel focused, brain waves are beta - in the last 20 minutes of each cycle we feel dreamy and tired, brainwaves are alpha

Answer 9

I:Evidence which supports distinct stages in the sleep cycle E: 9 Ppts had their sleep patterns monitored in a sleep lab through recording EEG/ brain wave activity and self reporting recollections of dreaming by being woken up at certain levels of sleep Results showed most dreaming occurred in REM sleep and brain activity its corresponded to how vivid dreams are C: sleep consists of two separate and distinct stages each categories by different brainwave activity and is therefore an example of an ultradian rhythms

Answer 10

I: methodological issues with research into unltradian rhythms E: when investigating sleep patterns, participants must be subjected to a specific level of control and be attached to monitors that measure such rhythms. This may be invasive for the participant, leading them to sleep in a way that does not represent their ordinary sleep cycle Sleep is also affected by factors such as: age, lifestyle, diet, illness Any of these factors could act as confounding variables C: this means that the research lacks both ecological and internal validity

Answer 11

Menstrual cycle

Answer 12

One cycle occurs every 28 days

Answer 13

Endogenous factors such as hormones in the endocrine system controlled by the hypothalamus and pituitary gland

Answer 14

- cycle of other women can cause cycles to become synchronised this is due to pheromones - these chemicals are detected through smell which influence behaviour and are emitted by females during menstruation - affected by light levels - found that a lack of light can shorten the cycle from 28 to 25-26 days (reinburg)

Answer 15

Seasonal affective disorder (SAD)

Answer 16

Thought to be experienced on a once yearly cycle

Answer 17

Depressive disorder where low mood, low energy and lack of interest in life is experienced in the winter months when the number of daylight hours is shorter than

Answer 18

- melatonin production - at night melatonin levels are higher and levels drop during daylight - in winter months, there is a lack of morning daylight meaning melatonin is produced for longer Affecting the production on serotonin in their brain ~ neurotransmitter linked to depression

Answer 19

I: practical applications of the research into infradian rhythms E E: one of the most effective treatments for SAD is phototherapy A light box that stimulated very strong light in the morning and evening Thought to re-set melatonin levels in people with SAD. Relives symptoms in up to 60% of sufferers C: means that lives of those that suffer with this disorder can be improved

Answer 20

I: many confounding factors which affect a women’s menstrual cycle E: nutrition, weight, stress, work shift pattern, smoking, alcohol Any patterns of synchronisation found in research could actually be due to these factors; and no more than what would have been expected to occur by chance C: likely that infradian rhythms are controlled by a combination of endogenous and exogenous factors

Biological Rhythms Flashcards

(45 cards)