Biological Rhythms Flashcards
what is a circadium rhythm
a rhythm that lasts for 24 hours
give an example of a circadum rhythm
sleep/wake cycle
what is an endogenous pacemaker
internal mechanisms that govern biological rhythms
what is the endogenous pacemaker involved in the sleep/wake cycle
the suprachiasmatic nucleus (SCN)
what are exogenous zeitbegeres
external factors in the eviornment that reset our biologial clocks through entrainment
what is the exogenous zeitberger that affects the sleep/wake cycle
light
explain how the SCN controls the sleep/wake cycle
- it recieves information about light from the optic chiasm
- the SCN passes on information on day length and light that it recieves to the pineal gland
- the pineal gland will increase the production of melatonin during periods of sleep and inhibits during wakefullness
what is the hormone associated with the sleep/wake cycle
melatonin
what is an infradian rhythm
rythyms that take longer than 24 hours
what are the 2 examples of an infradian rhythm
- menstrual cycle
- Seasonal affective disorder (SAD)
explain the menstrual cycle
- takes approximately 28 days to complete
- during each cycle, rising levels of the hormone oestrogen cause the ovary to develop an egg and release it
- after ovulation, the hormone progesterone helps the womb lining to grow thicker which readies the womb for pregnancy
explain SAD
- during the night the pineal gland secretes melatonin
- during winter, the lack of light in the morningmeans the secretion process continues for longer
- this affects the serotonin production in the brain
give evidence that supports the roe of melatonin in SAD
- terman found the rate of SAD is more common in the northern hemisphere where winter night are longer
- eg, SAD affects 10% of people living in new hampshire (northern USA) and 2% of residents in florida (southern)
what is an ultradian rhythm
rythym that takes less than 24 hours to complete
what is an examploe of an ultradian rhythm
sleep stages
how much sleep stages are there
5
explain stages 1 and 2 of sleep
- light sleep, easily woken
- stage 1: brain waves are high frequency and short amplitude - alpha waves
- stage 2: alpha waves continue but random sleep spindles
explain stages 3 and 4 of sleep
- deep sleep, difficult to wake
- brain waves have a low frequency and high amplitude - delta waves
explain stages 5 of sleep
REM sleep
* body paralysed, brain active
* brain produces theta waves and eyes move around
* dreams most often experiences
give research to support the effect of shift work and mistakes
boivin et al
* workers experince reduced concentraion around 6 am
* mistakes more likely
how does the circadium rhythm in teenagrs differ to adults
- teenagers have a later circadium rhythm
- melatonin release: teenagers = 10:30pm, adults = 9pm
- melatonin inhibition: teenagers = 9am, adults = 7:30 am
give rsearch that contradicts light as an exogenous zeitberger
siffre
* caveman who spent an extended period in a cxave deproved of natural light and sound
* his circadiun rhythm settled to around 25 hours
give research that highlights the importance of light as an exogenous zeitberger
campbell and murphy
* light was shone at participants knees at various timkes when they were woken up
* rsearches deviarted the participants circadiun rhythm
give a PEELH for light as an exogenous zeitberger
limitation
P - contradicting evidence
Eg - siffre, caveman who spent extended period in a cave with no exposure to light. his biological rhythm settled to 25 hours
Ex - shows light is not important in relation to the biological clock
L - the effect of light as an EZ lacks validity
H - study conducted on oe person so cannot be generalised
