Biological Rhythms

Question 1

what is a circadium rhythm

Answer 1

a rhythm that lasts for 24 hours

Question 2

give an example of a circadum rhythm

Answer 2

sleep/wake cycle

Question 3

what is an endogenous pacemaker

Answer 3

internal mechanisms that govern biological rhythms

Question 4

what is the endogenous pacemaker involved in the sleep/wake cycle

Answer 4

the suprachiasmatic nucleus (SCN)

Question 5

what are exogenous zeitbegeres

Answer 5

external factors in the eviornment that reset our biologial clocks through entrainment

Question 6

what is the exogenous zeitberger that affects the sleep/wake cycle

Answer 6

light

Question 7

explain how the SCN controls the sleep/wake cycle

Answer 7

• 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

Question 8

what is the hormone associated with the sleep/wake cycle

Answer 8

melatonin

Question 9

what is an infradian rhythm

Answer 9

rythyms that take longer than 24 hours

Question 10

what are the 2 examples of an infradian rhythm

Answer 10

• menstrual cycle
• Seasonal affective disorder (SAD)

Question 11

explain the menstrual cycle

Answer 11

• 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

Question 12

explain SAD

Answer 12

• 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

Question 13

give evidence that supports the roe of melatonin in SAD

Answer 13

• 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)

Question 14

what is an ultradian rhythm

Answer 14

rythym that takes less than 24 hours to complete

Question 15

what is an examploe of an ultradian rhythm

Answer 15

sleep stages

Question 16

how much sleep stages are there

Answer 16

5

Question 17

explain stages 1 and 2 of sleep

Answer 17

• 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

Question 18

explain stages 3 and 4 of sleep

Answer 18

• deep sleep, difficult to wake
• brain waves have a low frequency and high amplitude - delta waves

Question 19

explain stages 5 of sleep

Answer 19

REM sleep
* body paralysed, brain active
* brain produces theta waves and eyes move around
* dreams most often experiences

Question 20

give research to support the effect of shift work and mistakes

Answer 20

boivin et al
* workers experince reduced concentraion around 6 am
* mistakes more likely

Question 21

how does the circadium rhythm in teenagrs differ to adults

Answer 21

• teenagers have a later circadium rhythm
• melatonin release: teenagers = 10:30pm, adults = 9pm
• melatonin inhibition: teenagers = 9am, adults = 7:30 am

Question 22

give rsearch that contradicts light as an exogenous zeitberger

Answer 22

siffre
* caveman who spent an extended period in a cxave deproved of natural light and sound
* his circadiun rhythm settled to around 25 hours

Question 23

give research that highlights the importance of light as an exogenous zeitberger

Answer 23

campbell and murphy
* light was shone at participants knees at various timkes when they were woken up
* rsearches deviarted the participants circadiun rhythm

Question 24

give a PEELH for light as an exogenous zeitberger

Answer 24

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