Consciousness And Sleep

Question 1

What is arousal?

Answer 1

Emotional state associated with an aim or to avoid something

Question 2

What is consciousness?

Answer 2

Awareness of internal and external environments

Question 3

What is responsible for consciousness?

Answer 3

Cerebral cortex

Reticular formation

Question 4

What is the reticular formation?

Answer 4

Group of specialised interneurones in the brainstem

Question 5

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

Answer 5

Stimulate each other in a positive feedback loop

Question 6

What sends inputs to the reticular formation?

Answer 6

Sensory neurones

Cerebral cortex

Question 7

What are the outputs of the reticular formation delivered to?

Answer 7

Thalamus

Hypothalamus

Basal forebrain nuclei

Spinal cord

Question 8

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

Answer 8

Glutamate, excitatory

Question 9

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

Answer 9

Histamine, excitatory

Question 10

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

Answer 10

Acetylcholine, excitatory

Question 11

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

Answer 11

Reticular activating system RAS

Question 12

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

Answer 12

Reticulospinal tracts

Question 13

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

Answer 13

Drowsiness

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

Question 14

What are the methods used to assess consciousness?

Answer 14

Glasgow coma scale GCS

Electroencephalogram EEG

Question 15

How does the Glasgow coma scale work?

Answer 15

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

Question 16

How does an EEG measure consciousness?

Answer 16

Measures activity of neurones in the cerebral cortex

Question 17

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

Answer 17

Fire action potentials in a synchronised manner

Question 18

What are the stages of sleep?

Answer 18

Eyes open

Eyes closed

REM sleep

Stage 1

Stage 2

Stage 3

Stage 4

Question 19

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

Answer 19

Beta waves

Question 20

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

Answer 20

Alpha waves

Question 21

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

Answer 21

Beta waves

Question 22

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

Answer 22

Because cerebral cortex gives inputs to visual system

Hence similar EEG appearance to having eyes open

Question 23

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

Answer 23

Alpha waves

Occasional theta waves

Question 24

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

Answer 24

Theta waves

Occasional sleep spindles, K complexes

Question 25

What do sleep spindles represent?

Answer 25

Activity of the thalamus trying to return to awake state

Question 26

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

Answer 26

K complexes, now called delta waves

Question 27

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

Answer 27

High frequency to low frequency Low amplitude to high amplitude Due to neuronal synchronisation

Question 28

How many stages of sleep does a person pass through?

Answer 28

Pass through all stages in order, multiple times

Question 29

What is the mechanism of sleep?

Answer 29

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

Question 30

What initiates REM sleep?

Answer 30

Groups of neurones in the pons

Question 31

How is REM sleep initiated?

Answer 31

Strong inhibition of the thalamus Inhibition of lower motor neurones by glycnergic neurones

Question 32

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

Answer 32

The reticular formation

Question 33

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

Answer 33

Travel down reticulospinal tracts in the spinal cord

Question 34

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

Answer 34

Loss of muscle tone | To prevent muscle movements during dreaming

Question 35

What are the functions of sleep?

Answer 35

Healing Removal of waste products Energy conservation Memory consolidation

Question 36

What are some examples of sleep disorders?

Answer 36

Insomnia Narcolepsy Sleep apnoea

Question 37

What is the most common sleep disorder?

Answer 37

Insomnia

Question 38

What is insomnia?

Answer 38

Sleeplessness - difficulty falling asleep - falling asleep but only for a short time

Question 39

What causes insomnia?

Answer 39

Hormone shifts e.g. menopause, hyperthyroidism Mental disorders e.g. depression, anxiety

Question 40

What is narcolepsy?

Answer 40

Decreased ability to regulate sleep-wake cycles

Question 41

What causes narcolepsy?

Answer 41

Dysfunction of neurotransmission in neurones responsible for sleep

Question 42

What is sleep apnoea?

Answer 42

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

Question 43

What causes sleep apnoea?

Answer 43

Blockage of airways

Question 44

What are some examples of consciousness disorders?

Answer 44

Brain death Coma Locked in syndrome

Question 45

What is brain death?

Answer 45

Complete loss of brain function

Question 46

What does brain death look like on an EEG?

Answer 46

Flat EEG

Question 47

What is a coma?

Answer 47

State of unconsciousness | Person cannot be awakened

Question 48

What causes coma?

Answer 48

Injury to cerebral cortex or reticular activating system | Due to drug poisoning or hypoxia usually

Question 49

What does a coma look like on en EEG?

Answer 49

Various patterns

Question 50

What is locked-in syndrome?

Answer 50

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

Question 51

What causes locked in syndrome?

Answer 51

Poisoning, drugs Brainstem stroke Trauma

Question 52

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

Answer 52

Normal