Week 11

Question 1

Biorhythms in nature

Answer 1

-Timing mechanisms that control various biological processes
-Annual: migrations, mating
-Seasonal: photosynthesis in plants
-Daily: sleep-wake cycle

Question 2

Sleep wake cycle

Answer 2

-Circadian rhythm
-Approx 24 hours in humans
-Changes across species associated with metabolic rate
-Works by endogenous clock

Question 3

What makes the endogenous clock work

Answer 3

Suprachiasmatic nucleus (SCN) in hypothalamus

Question 4

Exogenous cues for body clock

Answer 4

Light
-Specialised cells in retina
-Sleep period related to the increase in melatonin
-Daylight/blue light surpasses melatonin secretion

Food
Activity

Question 5

Genes for sleep-wake cycle?

Answer 5

-PER gene
-ROle in protein synthesis in SCN
-Different alleles associated with morning vs evening types

Question 6

Sleep definition

Answer 6

-A reversible behavioural state of perceptual disengagement from, and unresponsiveness to, the environment.

Question 7

Sleep Recording

Answer 7

Polysomnography
-Recording of electrical current from scalp, eyes, and chin
-EEG: head electrodes detect electrical activity on brain
-EOG: eye electrodes detect eye movements
-EMG: chin electrodes measure muscle tone

Question 8

Slow-wave sleep and REM sleep (Autonomic activity)

Answer 8

-Heart rate: slow decline in SWS, variable with high bursts in REM
-Breathing: slow decline in SWS, variable with high bursts in REM
-Thermoregulation: Maintained in SWS, variable, with high bursts in REM

Question 9

Slow wave sleep and REM sleep (Muscular system)

Answer 9

Postural tension: Progressively reduced in SWS, eliminated in REM