Consciousness And Sleep Flashcards Preview

Sem 4 - Nervous System > Consciousness And Sleep > Flashcards

Flashcards in Consciousness And Sleep Deck (52)
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1
Q

What is arousal?

A

Emotional state associated with an aim or to avoid something

2
Q

What is consciousness?

A

Awareness of internal and external environments

3
Q

What is responsible for consciousness?

A

Cerebral cortex

Reticular formation

4
Q

What is the reticular formation?

A

Group of specialised interneurones in the brainstem

5
Q

How do the cerebral cortex and reticular formation relate to each other?

A

Stimulate each other in a positive feedback loop

6
Q

What sends inputs to the reticular formation?

A

Sensory neurones

Cerebral cortex

7
Q

What are the outputs of the reticular formation delivered to?

A

Thalamus

Hypothalamus

Basal forebrain nuclei

Spinal cord

8
Q

What do the neurones from the reticular formation to the thalamus release as their neurotransmitter? What effect does it have?

A

Glutamate, excitatory

9
Q

What do the neurones from the reticular formation to the hypothalamus release as their neurotransmitter? What effect does it have?

A

Histamine, excitatory

10
Q

What do the neurones from the reticular formation to the basal forebrain nuclei release as their neurotransmitter? What effect does it have?

A

Acetylcholine, excitatory

11
Q

What do the neurones from the reticular formation to the thalamus, hypothalamus and basal forebrain nuclei form?

A

Reticular activating system RAS

12
Q

What do the neurones from the reticular formation to the spinal cord form?

A

Reticulospinal tracts

13
Q

What is a common side effect of antihistamines and anticholinergic drugs? Why?

A

Drowsiness

Because they inhibit the effects of neurones from the reticular formation to the hypothalamus and basal forebrain nuclei

14
Q

What are the methods used to assess consciousness?

A

Glasgow coma scale GCS

Electroencephalogram EEG

15
Q

How does the Glasgow coma scale work?

A

Give points based on different aspects of patient’s condition
Add up points to get total scare
Higher score means are more conscious

16
Q

How does an EEG measure consciousness?

A

Measures activity of neurones in the cerebral cortex

17
Q

What happens to neurones in the brain if inputs from the somatosensory system are reduced?

A

Fire action potentials in a synchronised manner

18
Q

What are the stages of sleep?

A

Eyes open

Eyes closed

REM sleep

Stage 1

Stage 2

Stage 3

Stage 4

19
Q

What is seen on an EEG when a person has their eyes open?

A

Beta waves

20
Q

What is seen on an EEG when a person has their eyes closed?

A

Alpha waves

21
Q

What is seen on an EEG when a person is in REM sleep?

A

Beta waves

22
Q

Why are beta waves seen on an EEG when a person is in REM sleep?

A

Because cerebral cortex gives inputs to visual system

Hence similar EEG appearance to having eyes open

23
Q

What is seen on an EEG when a person is in stage 1 sleep?

A

Alpha waves

Occasional theta waves

24
Q

What is seen on an EEG when a person is in stage 2 and 3 sleep?

A

Theta waves

Occasional sleep spindles, K complexes

25
Q

What do sleep spindles represent?

A

Activity of the thalamus trying to return to awake state

26
Q

What is seen on an EEG when a person is in stage 4 sleep?

A

K complexes, now called delta waves

27
Q

How do the waves on an EEG change in appearance from beta to alpha to theta to delta? Why?

A

High frequency to low frequency
Low amplitude to high amplitude

Due to neuronal synchronisation

28
Q

How many stages of sleep does a person pass through?

A

Pass through all stages in order, multiple times

29
Q

What is the mechanism of sleep?

A

Inhibition of reticular activating system
Inhibition of positive feedback loop between the reticular activating system and the cerebral cortex

Inhibition of the thalamus by reducing inputs from the somatosensory system

30
Q

What initiates REM sleep?

A

Groups of neurones in the pons

31
Q

How is REM sleep initiated?

A

Strong inhibition of the thalamus

Inhibition of lower motor neurones by glycnergic neurones

32
Q

Where do the glycinergic neurones that inhibit the lower motor neurones arise from?

A

The reticular formation

33
Q

How do the glycinergic neurones from the reticular system reach the lower motor neurones?

A

Travel down reticulospinal tracts in the spinal cord

34
Q

What is the purpose of inhibiting lower motor neurones during REM sleep?

A

Loss of muscle tone

To prevent muscle movements during dreaming

35
Q

What are the functions of sleep?

A

Healing

Removal of waste products

Energy conservation

Memory consolidation

36
Q

What are some examples of sleep disorders?

A

Insomnia

Narcolepsy

Sleep apnoea

37
Q

What is the most common sleep disorder?

A

Insomnia

38
Q

What is insomnia?

A

Sleeplessness

  • difficulty falling asleep
  • falling asleep but only for a short time
39
Q

What causes insomnia?

A

Hormone shifts e.g. menopause, hyperthyroidism

Mental disorders e.g. depression, anxiety

40
Q

What is narcolepsy?

A

Decreased ability to regulate sleep-wake cycles

41
Q

What causes narcolepsy?

A

Dysfunction of neurotransmission in neurones responsible for sleep

42
Q

What is sleep apnoea?

A

Pauses in breathing or shallow breathing during sleep
Leads to hypoxia
Wakes the patient up

43
Q

What causes sleep apnoea?

A

Blockage of airways

44
Q

What are some examples of consciousness disorders?

A

Brain death

Coma

Locked in syndrome

45
Q

What is brain death?

A

Complete loss of brain function

46
Q

What does brain death look like on an EEG?

A

Flat EEG

47
Q

What is a coma?

A

State of unconsciousness

Person cannot be awakened

48
Q

What causes coma?

A

Injury to cerebral cortex or reticular activating system

Due to drug poisoning or hypoxia usually

49
Q

What does a coma look like on en EEG?

A

Various patterns

50
Q

What is locked-in syndrome?

A

Patient is aware but cannot move, can only move their eyes

51
Q

What causes locked in syndrome?

A

Poisoning, drugs

Brainstem stroke

Trauma

52
Q

What does the EEG look like with locked-in syndrome?

A

Normal