biological rhythms

Question 1

what are biological rhythms

Answer 1

cyclical changes in the way that biological systems behave

Question 2

what are all biological rhythms governed by

Answer 2

endogenous pacemakers and exogenous zeitgebers

Question 3

what are the 3 biological rhythms

Answer 3

circadian
ultradian
infradian

Question 4

how long are circadian rhythms

Answer 4

about 24hrs

Question 5

how long are ultradian rhythms

Answer 5

less than 24hrs

they repeat more than once every 24hrs

Question 6

how long are infradian rhythms

Answer 6

more than 24hrs can be days, weeks, months, annual etc

Question 7

example of circadian rhythms

Answer 7

sleep-wake cycle
core body temperature
hormone production

they are all interrelated

Question 8

example of ultradian rhythms

Answer 8

the stages of sleep
basic rest activity cycle (brac) which is around 90mins
appetite

Question 9

example of infradian rhythms

Answer 9

female menstrual cycle (monthly rhythm)

Question 10

what are endogenous pacemakers

Answer 10

the internal body clock which regulates biological rhythms eg effects of suprachiasmatic nucleus

Question 11

what are exogenous zeitgebers

Answer 11

external/environmental cues that entrain our biological rhythms eg light which confuses the SCN

Question 12

what does entrain mean

Answer 12

to determine or to modify

Question 13

what is photoentrainment

Answer 13

when light provides input to the body clock

Question 14

what do light sensitive cells in the eyes detect and what do they do

Answer 14

detect brightness and send messages to SCN

Question 14

what does the SCN do with the info sent from brightness receptors

Answer 14

uses that info to coordinate activity of the circadian system

Question 14

where is the SCN located

Answer 14

in the hypothalamus

Question 15

according to the sleep wake cycle what time do we wake up

Answer 15

around 7am

Question 16

according to the sleep wake cycle what time do we feel most alert

Answer 16

around 11am

Question 17

according to the sleep wake cycle what time do we have a dip in alertness

Answer 17

in the afternoon

Question 18

according to the sleep wake cycle what time do we got to sleep

Answer 18

around 11pm

Question 19

according to the sleep wake cycle what time do we feel least alert

Answer 19

around 2am

Question 20

what is the circadian rhythm for hormones

Answer 20

hormone release at similar times each day

Question 21

what is the circadian rhythm for body temperature

Answer 21

body temp rising in the evening and falling during the night

Question 22

Explain how the sleep-wake cycle follows a circadian rhythm?

Answer 22

A circadian rhythm is a biological rhythm that lasts for 24 hours.

Each day we all have a time when our body naturally wakes up, we have a burst in energy during mid-morning, we have a slump in energy during the afternoon, we fall asleep at a similar time in the evening and we are at our lowest alertness around 2am
then the cycle starts again and repeats for the next day. Therefore, we all have a sleep/wake cycle that repeats every
24 hours.

Question 23

when is our body temperature at its lowest

Answer 23

around 4am

Question 24

when is our body temperature at its highest

Answer 24

around 6pm

Question 25

what is chronotherapeutics

Answer 25

Chronotherapeutics allows people to take drugs which then aren’t effective until necessary, hours later.

A Chronotherapeutics was developed using knowledge of the circadian rhythm.

Question 26

what does chronotherapeutics assume about people

Answer 26

that they all have the same circadian rhythm sleep wake cycle

Question 27

what type of study did duffy conduct

Answer 27

controlled observation

Question 28

what did duffy srudy

Answer 28

She studied differences in people’s sleep/wake cycles for a month.

she conducted a controlled observation looking into people’s sleep/wake cycles for a month.

Question 29

duffys findings

Answer 29

She found that other circadian rhythms like body temperature synchronised with people’s sleep/wake cycle.

She found two types of people: “morning people” who go to bed earlier and wake up earlier, and “evening people” who go to bed later and wake up later.

She found individual differences in people’s circadian rhythms.

Question 30

Question 4: Meera has low blood pressure which is worst in the morning. If she gets out of bed too fast or doesn’t do gentle movements first thing, she can become very light headed and even pass out. There are drugs that Meera can take, but if she took them the night before, their effects would have vanished by the time she woke up in the morning.

Answer 30

hronotherapeutics uses the knowledge of circadian rhythms to adjust the timing of drug activity. It means that the action of drugs can be delayed until the time of day when they would be most effective. For Meera, the drug needs to start working around the time she wakes up in the morning. That means that by using chronotherapeutics, Meera can take the drug at night before she goes to bed, and the drugs action will be delayed until the early hours of the morning.

Question 31

what are the stages of sleep

Answer 31

We are just starting to fall asleep and can be easily woken up. (1)

our heart rate starts to slow down and our temperature starts to drop. (2)

We fall into a deeper and deeper sleep.(3+4)

Our eyes move rapidly and our brain is active. (REM)

Question 32

3 things about basic rest activity cycle (BRAC)

Answer 32

It is an ultradian rhythm of alertness.
cycle lasts 90 minutes.
It helps to explain why professional musicians and athletes break up their practice into short segments.

Question 33

Tucker et al. didn’t manipulate any independent variables. Instead, they carefully controlled extraneous variables, like the levels of light and the amount of noise.

What type of study is this?

Answer 33

controlled observation

Answer 34

Tucker et al. conducted a controlled observation into people’s stages of sleep.

Tucker et al. found that there were individual differences in the amount of time people spent in each sleep stage.

Tucker et al. found that the biggest individual difference in amount spent in different sleep stages was during deep sleep.

The study showed that ultradian rhythms can vary between different people.

Question 35

Question 1: Liyana is so tired when she gets home from school that she often falls asleep while watching TV. Most of the time, if someone walks into the room it wakes her up, but sometimes she is so fast asleep that she doesn’t even notice. Explain the stages of the sleep cycle and explain why Liyana only sometimes wakes up.

Answer 35

There are
5
stages to the sleep cycle. The first four stages are called Stage
1
,
Stage
2
,
Stage
3
,
and Stage
4.
The final stage is called rapid eye movement (REM) sleep. Stages
1
and
2
are relatively light stages of sleep, they will be the stages of sleep Liyana is in when she is easily awoken. During stage
2
,
the heart rate and body temperature starts to drop. Stage
3
and Stage
4
are the deepest levels of sleep. This is when Liyana would not be awoken easily and does not notice when someone walks in the room. Finally, REM sleep is a further deep stage of sleep, however this one is characterised by an active brain and rapid eye movements. REM is also the stage most commonly associated with dreaming. We cycle through the
5
sleep stages on average every
90
minutes.

Question 36

ndividual differences in the sleep cycle are correct?

Answer 36

Tucker et al. found that the largest differences in time spent in a sleep stage were for stages
3
and
4.

Tucker et al. found there were large individual differences in the amount of time people spent in each stage of sleep.

Question 37

Explain the difference between infradian rhythms and ultradian rhythms. (2 marks)

Answer 37

The difference between infradian and ultradian rhythms is the duration of the rhythms, in that infradian rhythms are more than 24 hours (e.g. the menstrual cycle) whereas ultradian rhythms are less than 24 hours (e.g. stages of sleep).