L10 - Circadian Rhythms

Question 1

Describe biological rhythms

Answer 1

Cyclical changes in physiological systems which evolved due to the environment having cyclical changes (day/night and seasonal)

Question 2

3 types

Answer 2

Circadian (24 hrs)
Ultradian (under 24 hrs)
Infradian (over 24 hrs)

Question 3

The suprachiasmatic nuclei is located where and is what

Answer 3

In the hypothalamus

Pacemaker which controls the rate at which the body clock occurs

Question 4

Why is the SCN reset?

Answer 4

Constantly reset so the body is in sync with the outside world

Question 5

Describe photoentrainment

Answer 5

Natural light providing input to set the body clock to the correct time
Melanopsin acts as a brightness detector and sends messages about environmental light to the SCN

Question 6

SCN uses info on natural light from photoentrainment to do what?

Answer 6

Coordinate activity of circadian rhythms

Question 7

What is the sleep-wake cycle

Answer 7

Light and darkness determining when we need to sleep and when we wake up

Question 8

Sleep-wake cycle is under what control

Answer 8

Homeostatic control

Question 9

What happens when we’re awake for a long time?

Answer 9

Homeostasis tells us need for sleep is increasing due to amount of energy used when awake

Question 10

Circadian rhythms are maintained between what hours

Answer 10

Between 24-25 even without natural light

SWC

Question 11

Body temp is highest when

Answer 11

At 6pm

Question 12

Body temp is lowest at

Answer 12

4:30am

Question 13

Why does body temp rise just before we wake up?

Answer 13

So we feel alert

Question 14

Small temp drop occurs

Answer 14

During 2-4pm

Question 15

Melatonin is produced by

Answer 15

The pineal gland

Question 16

What is melatonin’s function?

Answer 16

Inhibit neural mechanisms that promote sleepiness

Question 17

More melatonin is produced when

Answer 17

During peak hours of darkness

Question 18

Strongest sleep drives occur when?

Answer 18

2-4am

1-3pm

Question 19

+ related to chronotherapeutics

Answer 19

Using circadian rhythms allow medication to be taken at right time to increase success
E.g. heart attack med isn’t released until 6am (most vulnerable time)

Question 20

• related to individual differences

Answer 20

Differences in circadian rhythms
Some people prefer to sleep and wake early, some sleep and wake late
Study found it varies from 12-165 hours

Question 21

• related to light

Answer 21

Doesn’t have to be natural light, can be artificial

Study using only artificial light changed from 22-28 hrs