Session 10

Question 1

What is the role of the reticular formation?

Answer 1

Regulates the level of arousal.

Question 2

What are the main inputs to the reticular formation?

Answer 2

Sensory system and the cortex.

Question 3

What are the main outputs from the reticular formation?

Answer 3

Thalamus, hypothalamus, basal forebrain nuclei and the spinal cord.

Question 4

Which neurotransmitter is used between the reticular formation and the thalamus/hypothalamus/basal forebrain nucleus?

Answer 4

ACh

Question 5

Which neurotransmitter is used between the thalamus and the cortex?

Answer 5

Glutamate

Question 6

Which neurotransmitter is used between the hypothalamus to the cortex?

Answer 6

Histamine

Question 7

Which neurotransmitter is used between the basal forebrain nucleus to the cortex?

Answer 7

ACh

Question 8

What is the role of the reticular formation?

Answer 8

Functions in sleep regulation, motor control, cadiorespiratory control, autonomic functions and motivation and reward.

Question 9

What is the role of the ascending reticular activating system?

Answer 9

Has many inputs, all of which output to the motor system, autonomic centres, thalamus and cortex, to raise the levels of consciousness.

Question 10

What is the role of the ARAS when an individual is awake (and REM sleep)?

Answer 10

Stimulates the cortex for consciousness. Also stimulates inhibitory neurones to act on inhibitory interneurones, further stimulating the cortex.

Question 11

What is the role of the ARAS during slow wave sleep?

Answer 11

The neurones from the ARAS are silent, hence no thalamo-cortical neurones are firing and there is significantly reduced consciousness.

Question 12

What inhibits the ARAS?

Answer 12

Hypothalamic sleep centres for sleep to occur.

Question 13

Describe the EEG recording of a normal, awake subject at rest.

Answer 13

High frequency beta-activity, low voltage pattern.

Question 14

Describe the EEG recording if a subject closed their eyes and became drowsy.

Answer 14

Lower frequency alpha-activity, but slightly higher voltage. Due to firing of many cortical neurones following thalamocortical activity.

Question 15

Describe the EEG recording of stage 1 sleep.

Answer 15

Alpha-activity with some theta waves.

Question 16

Describe the EEG recording of stage 2 sleep.

Answer 16

Mainly theta waves, with sleep spindles and k-complexes.

Question 17

Describe the EEG recording of stage 3 sleep.

Answer 17

Large amplitude, slow delta rhythms. Few eye and body movements.

Question 18

Describe the EEG recording of stage 4 sleep.

Answer 18

Deepest stage, large EEG rhythms of 2Hz or less.

Question 19

Give two reasons why sleep is important.

Answer 19

Resetting the CNS, memory and homeostasis.

Question 20

Describe non-REM sleep.

Answer 20

Stage 3 and 4. Slow wave sleep, active body and inactive brain. Eyes are still. Large role in neuroendocrine functioning. Decreased cerebral blood flow, oxygen consumption, blood pressure, and resp rate.

Question 21

Describe REM sleep.

Answer 21

Active brain and inactive body. EEG will appear as if awake. Individual is hard to disturb and commonly dreams. Irregular HR and RR, increased BMR and penile erection. Cholinergic and serotonergic neurones switch on REM sleep.

Question 22

What is narcolepsy?

Answer 22

Attacks of sleep where it does not normally occur. Can also cause sleep paralysis in which they remain awake at night. May be deficient in orexins.

Question 23

What is insomnia?

Answer 23

Chronic inability to fall asleep despite appropriate opportunities to do so. Can give hypnotics, e.g. benzodiazepines.

Question 24

What is sleep apnoea?

Answer 24

Interruption in breathing during sleep, leading to arousal from sleep or results in the lighter stages on non-REM sleep in order for breathing to be maintained. Upper airway at the back of the throat collapses during sleep.

Question 25

Which three mechanisms are involved in altered consciousness?

Answer 25

1) Reduced cortical function
2) Pressure effect on the brainstem
3) Direct lesion within the brainstem.

Question 26

Describe a coma.

Answer 26

Absence of consciousness. Impaired wakefulness and awareness. GCS<8/15. No purposeful movement or response to stimuli. E.g. due to drug poisoning, hypoxia, and stroke.

Question 27

Describe delirium.

Answer 27

Acute confusional state. Fluctuating arousal level, impaired awareness and disorientation.

Question 28

What is acute confusional state?

Answer 28

Range of clinical symptoms, primarily inattention. Causes include systemic medial conditions such as infections, metabolic derangements, toxins etc.

Question 29

What is a vegetative state?

Answer 29

Unresponsive wakefulness. Permanent if continues for more than 6 months to a year. Usually due to a major global brain injury.

Question 30

Give two intracranial and two extracranial causes of reduced consciousness.

Answer 30

Intra: haemorrhage, stroke, neoplasm, high ICP, infection.
Extra: hypoxia, electrolyte disturbance, metabolic disorder, sepsis, toxins, endocrine disorders.

Question 31

Describe the AVPU scale of assessment of consciousness.

Answer 31

A: alert - patient is fully awake
V: verbal stimulus - responds when you talk to them
P: painful stimulus - responds when you provide a painful stimuli
U: unresponsive - no eye, voice or motor response to voice or pain.

Question 32

Describe the glasgow coma scale.

Answer 32

Marked out of 15, and is a good measure of consciousness. Measures eye opening, verbal response and motor response.

Question 33

Describe the glasgow coma scale in terms of eye opening.

Answer 33

4= spontaneous
3= to speech
2= to pain
1= none

Question 34

Describe the glasgow coma scale in terms of verbal response.

Answer 34

5= orientated
4= confused 
3= inappropriate words
2= incomprehensible
1= none

Question 35

Describe the glasgow coma scale in terms of motor response.

Answer 35

6= obeys commands
5= localise pain
4= flexion to pain
3= flexion/withdrawal
2= extension to pain
1= none