biopsych 2

Question 1

biological rhythms - circadian

Answer 1

1. biological rhythms
   - every living organism is subject to bio r
   - they influence how our body systems behave
   - governed by 2 things
2. internal biological clock ( endogenous pacemaker )
3. external changes in environment ( exogenous zeitgeber )

frequency of occurrence :
- multiple times during the day - ultradian
- longer than 24 hrs - infradian
- much longer - circadian
- 24 hrs - circadian

sleep/wake cycle
- changes in alternes demonstrate the effect of daylight ( exogenous z )
- can also be governed by endogenous z ( scn )
- the scn is located just above the optic chiasm and provides the eye with info about light
- exogenous z can reset the scn

siffres case
- wanted to measure the effect of his own biological rhythms
- he wrnt into a cave for 2 months and had no source of natural light or sound but had adequate food and drink
- resurfaced after 2 months in mid september
- similar study done with a man who went into a texan cave for 6 months
- found that their free running biological rhythms were just over 24 hours which suggests that they continued to fall asleep and wake up at a regular schedule

other research
- aschoff and wever conducted a study with 11 ppts in a ww2 bunker for 4 weeks with no natural light
- all but 1 ppt displayed a circadian r of 24-25 hrs
- this and sifrres study suggests that the natural sleep wake cycle is just over 24 hours but is entrained by exogenous zeitgebers
- however we cannot overestimate the effects of exogenous zeitgebers on the internal biological clock as another study was done by folkard where 15 ppts lived in a dark cave for 3 weeks an went to sleep at 11:45 and woke up at 7:45 however the researchers gradually sped up the clock from 24 hrs to 22 hrs
- found that only 1 person comfortably adjusted to this which supports the existence of a strong free running circadian rhythms which can’t be overridden by exogenous z

Question 2

bio rhythms - circadian
- evaluation

Answer 2

1. medical treatment
   - increase effectiveness of drug treatment
   - circadian rhythms can co ordinate the body’s basic processes
   - chronotheraputics can increase effectiveness by being administering medical treatments to correspond with biological rhymes
   - for example aspirin for heart attacks is better to be taken late at night
2. individual differences
   - studies use small sample of ppts
   - there are variations and individual diffferences in a persons sleep wake cycle
   - research suggest it can vary from 13-65 hours for people
   - other research also shows that some people prefer going sleep early, waking up early etc ans the opposite which has an inclufence
   - stiffer himself found that with age his sleep wake cycle slowed down which suggests that it does have an impact
3. shift work
   - shift work can cause desynchronisation of biological rhythms
   - this desyn confiscation can therefor cause poor health or even more likely mistakes and accidents at around 6am which is dangerous eespcailly for healthcare workers
   - so we can use this knowledge to better manage shift work and give people specific times to work at to void disruption to their bio rhythms and its consequences

Question 3

endogenous pacemakers

Answer 3

scn
- scn is the main ep
- main one in all mammalian species
- influential in maintaining the circadian rhythms
- nerve fibres are connected to the eye cross in the optic chiasm and the scn is located directly above this
- receives info about light directly from its structure which continues even when we are asleep
- allows our biological clock to adjust to changes in light patterns even when we are asleep

anmal studies of scn
- study was done which disturbed scn connectetions im 30 chipmunks
- they were returned to their natural habitats and observed for 80 days
- found their sleep wake cycle disappeared and a significant proportion of them were killed because they were awake and active and vulnerable to attack during a time that they should have been asleep
- another study was done by ralph who bred mutant hamsters to have a 20 hour sleep wake cycle
- the scn cells in the foetal tissue of the mutant hamsters were transferred to the brains of normal hamsters
- was found their cycle had now defaulted to 20 hours

pineal gland and melatonin
- scn passes info about day length and light to pineal gland which secretes hormone of melatonin
- this occurs during the night and induces sleep and is inhibited during periods of wakefulness