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BB2 > Sleep and consciousness > Flashcards

Sleep and consciousness Flashcards

1
Q

What is consciousness?

A

Ability of an individual to react appropriately to stimuli in the outside world

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2
Q

How is consciousness clinically assessed?

A

Using Glasgow Coma Scale: max 15 points for being awake and alert

  • tests eye opening, verbal response and motor response
  • so better to ask how conscious is a person instead of is that person conscious= consciousness is not an all or nothing state but a continuum
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3
Q

What are the stages of consciousness?

A
  • coma (with or without reflexes present)
  • unconsciousness (unarousable, but maybe only temporarily by intense stimuli)
  • sleep (arousable by normal stimuli)
  • drowsy wakefulness (responding in non-reflex way)
  • normal wakefulness (responding to spoken/written stimuli)
  • high arousal (hyper alert and fast reactivity)
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4
Q

What are the categories of the Glasgow scale in terms of eye opening?

A
  • spontaneous
  • to sound
  • to pressure
  • none
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5
Q

What are the categories of the Glasgow scale in terms of verbal response?

A
  • orientated
  • confused
  • words
  • sounds
  • none
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6
Q

What are the categories of the Glasgow scale in terms of motor response?

A
  • obey commands
  • localising
  • normal flexion
  • abnormal flexion
  • extension
  • none
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7
Q

What is an electroencephalograph

A
  • measures brain arousal
  • small voltages recorded from scalp electrodes
  • average thousands of nerve cells so cannot be used to measure what individual neurons are doing
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8
Q

What are the uses of an EEG?

A
  • best for detecting seizure activity

- picks activity from muscles in head

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9
Q

What is the normal appearance of an EEG?

A
  • high frequency low amplitude signal

- desynchronised appearance as some neurons fire out of phase with others so cancel each other out

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10
Q

What is the appearance of an EEG in a seizure?

A

Synchronous firing

  • slow wave appearance with higher amplitude
  • more synchronous = less conscious
  • consciousness = function of desynchronization
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11
Q

What does sleep produce on an EEG?

A
  • cortical neuronal synchronisation
  • large amplitude slow waves which can be confused with a seizure
    (SLOW WAVE SLEEP)
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12
Q

What is the purpose of non-REM/slow wave sleep

A

Maintenance and Repair
Increased growth/maintenance of immune/nervous/skeletal and muscular systems
- GH secreted
- wound repair

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13
Q

What is the purpose of REM sleep?

A
  • EEG more like normal wave sleep
  • memory consolidation
  • removing junk and defragment memories
  • coping with life stresses
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14
Q

What is the role of antioxidants in sleep?

A
  • High levels of reactive oxygen species generated in the mitochondria
  • metabolic rates decrease in sleep
  • melatonin released from pineal gland
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15
Q

Where is the pineal gland?

A

At posterior border of 3rd ventricle

- endocrine organ

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16
Q

What is melatonin?

A

Powerful free radical scavenger

  • removes free radicals that have accumulated in waking
  • prevents seizures by maintaining GABA function
  • glycogen brain stores increase during sleep
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17
Q

What are the stages of sleep?

A

4 stages of normal/slow wave sleep
1 stage of paradoxical/REM sleep
- repeat in regular stages around 90 minute cycles

18
Q

Where does control of sleep and wakefulness occur?

A
  • in reticular formation of pons

- pontine centres modulated by hypothalamus which decides when we need more sleep

19
Q

Which chemicals are sleep inhibitors?

A

Ghrelin

Glucose

20
Q

Which chemicals are sleep inducers?

A

Leptin
Adenosine
Antihistamines

21
Q

How are chemicals regulating sleep and wakefulness controlled?

A
  • medial and ventrolateral preoptic nuclei in hypothalamus detect blood levels
  • preoptic nuclei project to tuberomammillary nucleus which has histaminergic neurons which are active during waking and silent during sleeping
  • preoptic nuclei may trigger sleep by inhibiting activity of TMN histaminergic neurons
22
Q

What happens in diurnal rhythms?

A

Suprachiasmatic nucleus receives input from retina

  • projects to TMN
  • neurons of retina fire continuous during daylight
23
Q

What is the cause of narcolepsy?

A
  • loss of orexins due to autoimmune attack from T cell lymphocytes on orexin-containing neurons
  • found in posterior hypothalamus
24
Q

What do orexins stimulate the release of?

A

Acetylcholine
Noradrenaline
Serotonin
Dopamine

25
Q

What is wakefulness maintained by?

A

Orexin

Histaminergic neurons

26
Q

When does sleep onset occur?

A

When signals from preoptic nuclei and suprachiasmatic nucleus inhibit histamine and orexin neurons
- they stop excitatory transmission to reticular formation of pons

27
Q

Where are the cell groups which maintain wakefulness found?

A

In reticular formation

28
Q

What are the cell groups which maintain wakefulness?

A
  • dopaminergic cells (in ventral tegmental area)

- cholinergic cells/acetylcholine (predunculopontine nucleus)

29
Q

What is the role of the dopaminergic cells in the ventral tegmental area?

A
  • at low level during sleep
  • nigrostriatal dopamine system activates basal ganglia during waking so we can move fluently
  • mesolimbic system activates limbic system
  • mesocortical system activates cortical system
30
Q

What do the cholinergic cells do?

A
  • project to the thalamus
  • cholinergic cells found in nucleus basalis that sends axons to all parts of cerebral cortex
  • adjacent to accumbens nucleus
  • activity increased in REM sleep and waking
31
Q

How are dreams different than waking?

A
  • we normally forget dreams (memory making parts switched off)
  • lower motor neurons are paralysed (apart from respiratory and extraocular muscles)
32
Q

What is the locus coeruleus?

A

The noradrenergic cells

33
Q

What does the noradrenaline system do?

A
  • during all forms of sleep neurons drop to low level
  • control center for SNS
  • projects to cerebral cortex and activates a form of central sympathetic system to activate alertness and attention for us to retrieve memory and use in dreams
34
Q

What do serotonergic cells do during sleep?

A

Cells stop during REM sleep activity

35
Q

What is the theory of the function of serotonergic cells during sleep?

A

Maintain connection between UML and LMN

  • motor cortex active in sleep
  • don’t move as believe that without firing of serotonin connection will not happen
  • sleepwalking is thought to be failure of motor disconnection during REM
36
Q

What is the role of amphetamine?

A

Prevent sleep by continually releasing dopamine/noradrenaline despite amine cell bodies in brainstem being inactive

37
Q

What do SSRIs do to sleep?

A

Reduce duration of REM sleep

  • serotonin ceases during sleep so if kept high might decrease efficiency of sleep
  • also memory loss of REM used to consolidate memory
38
Q

What is the role of antidepressants and sleep?

A

TCA - enhance sleep as block H1 receptors/noradrenaline reuptake
MOAs - reduce sleep as increase noradrenaline/dopamine/serotonin levels

39
Q

How is insomnia treated?

A
  • lifestyle changes
  • CBT
  • Antihistamines
  • Benzodiazapines
  • Zopiclone (increase release of GABA)
40
Q

What is the cause of sleep apnea?

A
  • motor disconnection during REM must specifically avoid respiratory system otherwise stop breathing
  • muscles of throat relax too much obstructing airways
  • can lead to sudden infant death syndrome

BB2 (31 decks)

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