Sleep-Wake Cycle

Question 1

Biological function of sleep

Answer 1

Recuperation (homeostasis) and adaptation (protect from danger)
two theories

Question 2

Electroencephalogram (EEG)

Answer 2

Reveals gross electrical activity of the brain

Question 3

Eclectrooculogram (EOG)

Answer 3

Records eye movements seen during rapid eye movement (REM) sleep

Question 4

Electromtogram (EMG)

Answer 4

Detects loss of activity in neck muscles during some sleep stages

Question 5

Four stages of sleep (EEG)

Answer 5

Sleep: voltage increase and frequency decreases (slows) with the progression through stages 1-4
1. theta waves
2. spindles and k complexes
3. occasional delta waves
4. predominantly delta waves

Question 6

Function of spindle and K complexes

Answer 6

Determining response to stimulus while sleeping. Spindle is thalamus activity, if there is a problem with the stim, then up to cortex which is the K complex

Question 7

Course of sleep and REM

Answer 7

90 minute cycles up and down between the four stages, with the stage ones after the first one occurring with REM and lack of core-muscle tone (Emergent stage one (dreaming))
You wake up a few times before you really wake up

Question 8

What is the most restorative sleep?

Answer 8

Deep sleep, 1st hour and half to three hours

Question 9

What is not impaired by lack of sleep?

Answer 9

logical and critical thinking
retained physical strength and motor performances

Question 10

Zeitgebers

Answer 10

environmental cues that entrain circadian rhythms, which affect basically all biological processes

Question 11

what is the function of the sun for circadian rhythms?

Answer 11

our internal clock runs on 25 hours so the sun ensures we all run on similar, corrected clocks

Question 12

What nucleus in the hypothalamus manages our internal circadian clock

Answer 12

suprachiasmatic nucleus (SCN)

Question 13

If there is a lesion to the SCN, what happens?

Answer 13

Does not reduce sleep time but interrupts its periods

Question 14

SCN detects sunlight how?

Answer 14

It sits right above the optic chasm and there are retinal ganglion cells that are photosensitive (not activated by rods or cones)
10% of blind people lack these cells and have free-running sleep-wake cycles
Optic nerves must be in tact but not the tracts

Question 15

What two parts manage sleep?

Answer 15

Anterior hypothalamus
Caudal reticular REM nuclei

Question 16

What two parts manage wake?

Answer 16

Posterior hypothalamus (locus serouilus)
Rostral reticular formation

Question 17

Sleep need

Answer 17

the homeostatic process whose magnitude depends on the amount of prior sleep and wakefulness

Question 18

Sleep urge

Answer 18

the circadian process which is governed by SCN

Question 19

Describe the sleep/wake circuit

Answer 19

It is a competition between vIPOA and locus ceroolius

LC sends out Neuroepiinerpherin and the lateral hypothalamic area responds with orexin to strengthen the LC, and the LC also inhibits via ACh the caudal reticular formation

Meanwhile, throughout the day the vIPOA is inhibited by the LC, but sleep need in increasing via adenosine (no more ATP), and the urge is developed by the SCN

Question 20

How does the 90 minute cycle of REM work?

Answer 20

Rising and falling activity and inhibition in caudal reticular formation – once it is signaling awakeness it falls back down bc of inhibition

Question 21

What is the function of the pineal gland?

Answer 21

Releases melatonin to suppress SCN

Question 22

hypnotic drugs

Answer 22

enhance the effect of inhibitory neurontranmitter GABA
Depresses wakeful centers

Question 23

anti hypnotic drugs

Answer 23

increases the activity of catecholamine transmitters

Question 24

chronobiotic

Answer 24

increases the level of melatonin in the brain