Sem 3, case 10 (sleep)

Question 1

What is the circadian rhythm?

Answer 1

“Biological clock”

A 24hour cycle that’s “Resettable” by external stimuli / responds to internal/external stimuli including temperature

Question 2

What are the biological markers used to time/formulate the circadian rhythm?

Answer 2

Melatonin synthesis
Temperature
Cortisol production (high in morning, lowest in the evening)

Question 3

Briefly describe the cortisol production cycle within a day…

Answer 3

Highest in the morning
Reduces throughout the day
Drops significantly in evening/early stages of sleep

Question 4

What are the 4 main stages of sleep?

Answer 4

• non-REM 1 (very light sleep)
• non-REM 2 (intermediate sleep)
• non-REM 3 (deep sleep)
• REM

Question 5

What happens physiologically as a person progresses through sleep stages NREM 1 and 2?

Answer 5

Heart rate decreases
Muscles relax
Body temp drops
Electrical brain activity slows

Question 6

What happens in the body when a person enters stage 3 NREM sleep?

Answer 6

• lowest heart rate/body temp of all stages
• muscle recovery/growth
• bone recovery/growth
• immune system recharges/strengthens

Question 7

What happens during REM sleep?

Answer 7

• brain activity speeds up = dreams
• brain starts problem solving
• memory consolidation
• heart rate, blood pressure, body temp INCREASES
• muscles are paralysed (stops acting out dreams)

Question 8

How long is an average sleep cycle?

Answer 8

90 mins

Question 9

Which hormone controls the circadian rhythm?

Answer 9

Melatonin

Question 10

Where is the suprachiasmatic nucleus (SCN) located?

Answer 10

Hypothalamus

Question 11

What photopigment is activated by light levels, with regards to the circadian rhythm?

Answer 11

Melanopsin

Question 12

What is the biological physiology of the circadian rhythm?

Answer 12

• retinal ganglion cells (RGCs) containing melanopsin receive info about light levels
• these RGCs send signals to suprachiasmatic nucleus (SCN)
• via retino-hypothalamic tract
• SCN transmits info about light level to PINEAL GLAND
• via PVN (paraventricular nucleus), IML (intermedioloateral zone) and SCG (sup. Cervical ganglia)
• pineal gland secretes MELATONIN in response

Question 13

Say how melatonin release differs depending on light levels…

Answer 13

MORE melatonin released in DARK
LESS melatonin released in LIGHT

Question 14

Where is the Pineal gland located?

Answer 14

In the epithalamus

Question 15

What structures make up the diencephalon?

Answer 15

• epithalamus
• thalamus
• subthalamus
• hypothalamus

Question 16

In which stage of sleep is bruxism (teeth grinding) found?

Answer 16

NREM 2

Question 17

What does an EEG stand for?

Answer 17

Electro-encephalogram

Question 18

What difference is seen on an EEG that characterises REM sleep?

Answer 18

A change from a synchronised to desynchronised EEG

Question 19

When is an EEG desynchronised?

Answer 19

During:
- wakefulness
- REM sleep

Question 20

What are the 4 states of consciousness?

Answer 20

• consciousness
• concussion
• coma
• vegetative state