Sleep

Question 1

where does the sleep process originate?

Answer 1

the pons, reticular formation

Question 2

what is the difference between sleep and coma?

Answer 2

in sleep a person can be aroused with normal stimuli (light, noise, touch) but in a coma they cant

Question 3

what can electrical stimulation of the suprachiamatic nuclei promote?

Answer 3

sleep

Question 4

what is orexin?

Answer 4

excitatory neurotransmitter released by the hypothalamus that is required for wakefulness

Question 5

what can defective orexin signalling cause?

Answer 5

narcolepsy

Question 6

describe the positive feedback from the CNS and PNS that sustains wakefulness

Answer 6

> excitatory neurons in ascending reticular activating system (part of the reticular formation) are released from inhibition from sleep centres
this stimulates excitatory pathways in the CNS and PNS
this becomes a positive feedback system

Question 7

what happens when excitatory signals fade and cells become fatigued in the positive feedback wakefulness system?

Answer 7

inhibitory peptide signals form the sleep centres in the reticular formation take over and rapidly inhibit the weakening excitatory signals leading to rapid progression into the sleep state

Question 8

in an eeg recording what does the frequency increase with?

Answer 8

neuronal excitation

Question 9

name the four main types of wave pattern seen on an eeg

Answer 9

> alpha
beta
theta
delta

Question 10

what waves would you expect to see on an eeg in a relaxed awake state?

Answer 10

high frequency, high amplitude, alpha waves

Question 11

describe eeg waves seen in someone in an alert awake state

Answer 11

very high frequency with a low amplitude, beta waves

Question 12

why is low amplitude seen in beta waves on an eeg?

Answer 12

the person is alert and awake and the increase in activity is asynchronous as the brain is too busy. opposing polarities of signals cancel each other out and do not get recorded

Question 13

what are theta waves?

Answer 13

these are low frequency waves which can vary in amplitude. they are common in children and are seen in emotionally stressed adults. they also occur during sleep

Question 14

what waves occur in very deep sleep?

Answer 14

delta waves

Question 15

describe delta waves

Answer 15

very low frequency but high amplitude

Question 16

what is stage 1 of the sleep cycle?

Answer 16

> slow wave
slow eye movements
light sleep, easily rousable
high amplitude, low frequency theta waves

Question 17

describe stage 2 of the sleep cycle

Answer 17

> eye movements stop
frequency slows
bursts of rapid waves called sleep spindles

Question 18

describe stage 3 of the sleep cycle

Answer 18

> high amplitude, very slow delta waves
interspersed with short episodes of faster waves
spindle activity declines

Question 19

what stage of sleep is exclusively delta waves?

Answer 19

stage 4

Question 20

from what stage of sleep is it difficult to rouse someone and walking/talking can occur?

Answer 20

stages 3 and 4

Question 21

what is the 5th stage of sleep?

Answer 21

> REM sleep
fast waves (similar to being awake)
dreams occur during rem sleep

Question 22

what is associated with deep slow wave sleep occurring in the first few hours of sleep?

Answer 22

decreased vascular tone, respiratory and basal metabolic rate

Question 23

describe eeg waves during rem sleep

Answer 23

> desynchronised
high frequency
low amplitude

Question 24

what inhibits skeletal muscles in REM sleep?

Answer 24

inhibitory projections form the pons to the spinal cord

Question 25

what is rem sleep dependent on?

Answer 25

cholinergic pathways within the reticular formation and their projections to the thalamus, hypothalamus and cortex.

Question 26

what does anticholinesterases increase?

Answer 26

time spent in REM sleep

Question 27

what is the effect of REM sleep on heart and respiratory rate?

Answer 27

they become irregular

Question 28

what do sleep deprive subjects demonstrate without exception?

Answer 28

> impaired cognitive ability
impaired physical performance
sluggishness
irritability

Question 29

what does sleep support?

Answer 29

> neuronal plasticity
> learning and memory
> cognition
> clearance of waste products from central nervous system
> conservation of whole body energy
> immune function

Question 30

define insomnia

Answer 30

chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour

Question 31

what must you distinguish in insomnia?

Answer 31

whether it is chronic, primary insomnia or temporary secondary insomnia

Question 32

what are the negative effects of benzodiazepines?

Answer 32

they are addictive and cause problems on withdrawal

Question 33

what is somnambulism?

Answer 33

sleep walking

Question 34

in what stage does somnambulism occur?

Answer 34

exclusively in non-REM sleep and mainly in stage 4

Question 35

describe narcolepsy

Answer 35

patients enter directly into REM sleep with little warning. it is linked to dysfunctional orexin release from the hypothalamus

Question 36

where is the “master clock” of cardiac rhythm located?

Answer 36

in the suprachiasmatic nucleus of the hypothalamus just above the optic chiasma

Question 37

what entrains 24 hour cycle in neurons in the suprachiasmatic nucleus ?

Answer 37

external clues such as dark and light cycles

Question 38

what happens if the suprachiasmatic nucleus is destroyed?

Answer 38

circadian rhythm is lost