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Y2 - CNS > Lecture 11 - Brainstem, Arousal, Sleep And Consciousness > Flashcards

Lecture 11 - Brainstem, Arousal, Sleep And Consciousness Flashcards

1
Q

What is the Definiton of arousal?

A

Emotional state associated within a goal or avoiding something noxious or toxic

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2
Q

What is the definition of sleep?

A

The readily reversible state of reduced responsiveness to and interaction with theee environment

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3
Q

What is the definition of consciousness/

A

Hard to define

It’s related to the awareness of external environment and internal states

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4
Q

What are the 2 main components required for consciousness?

A

Functioning cerebral cortex
Functioning reticualr formation

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5
Q

What is the reticular formation/where is it found?

A

Diffuse network of interneurones running entire length of brainstem continous with white matter tracts from teh spinal cord and diencephalon

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6
Q

What are the 3 columns of the reticular formation?

A

Median
Medial
Lateral

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7
Q

What is the function of the median column of the reticular formation?

A

Arousal
Emotion

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8
Q

What is the function of the medial column of the reticular formation?

A

Somatosensory input processing

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9
Q

What is the function of the lateral column of the reticular formation?

A

Cranial nerve activity
Micturition

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10
Q

What are the 2 main inputs to the reticular formation?

A

Cortex
Sensory system

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11
Q

What is the overall role of the reticular formation?

A

Keeps the cortex awake/functioning (reticular activating system does this)

Integrate, relay and coordinate vital life functions and protective reflexes

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12
Q

What are the 3 main cortical regions which the reticular formation sends impulses to?

A

Thalamus
Hypothalamus
Basal forebrain nuclei

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13
Q

What neurotransmitter travels along the axons which are sent from the reticular formation to the thalamus?

A

Glutamate

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14
Q

What neurotransmitter travels along the axons which are sent from the reticular formation to the Hypothalmus?

A

Histamine (H hypothalamus H Histamine)

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15
Q

What neurotransmitter travels along the axons which are sent from the reticular formation to the basal forebrain nuclei?

A

Acetylcholine (ACh)

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16
Q

What type of feedback loop occur between the cortex and reticular formation when there’s a binary outcome (sleep or awake e.g)?

A

Postive feedback

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17
Q

How does the reticular activating system maintain wakefulness?

A

Reticualr activating system receives excitatory input from cortex, projects it’s own excitatory input back to cortex forming + feedback loop

Info sent to cortex amintaingni arousal and consciousness and blocking pathways promoting sleep

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18
Q

What nuclei of the reticular formation send the projections to the hypothalamus, thalamus and basal forebrain nuclei?

A

Median raphe

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19
Q

What are the 2 ways by which we can assess/measure cortical function?

A

Electroencephalogram (EEG)

Glasgow Coma Scale (GCS)

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20
Q

What is the Glasgow Coma Scale?

A

Clinical assesment of consciousness used to measure level of cerebral activity

Useful to localise lesion to cerebral cortex or brain stem

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21
Q

What 3 responses does the Glasgow Coma Scale (GCS) measure?

A

EMV

Eye repsonse
Motor response
Verbal response

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22
Q

What is better, a high GCS score or lower GCS score?

A

Higher GCS score

Indicates higher level of CNS function and less CNS dameage

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23
Q

What is the GCS scored out of?

A

15

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24
Q

What is the significance of a patient spontaneously opening their eyes? (GCS)

A

Cortical function is fine

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25
What is the significance of a patient only opening their eyes when you tell them to? (GCS)
Slightly diminished cortical function but still functioning brainstem
26
What is the significance of a patient only opening their eyes when receiving pain stimulus? (GCS)
Impaired cortical function Brainstem preserved since reflex functional
27
What is the significance of a patient not opening their eyes? (GCS)
Severe damage too brainstem (maybe also cortex)
28
What is the significance of a patient being able to obey commands for the motor repsonse part of GCS?
Normal function
29
What is the significance of a patient being able to localise to stimuli after a painful stimulus for the motor repsonse part of GCS?
Diminished higher cortical function but connections from sensory and motor cortex fine
30
What is the significance of a patient withdrawing to pain for the motor repsonse part of GCS?
Still a physiological reflex repsonse to stimuli so brainstem is fine
31
What is the significance of a patient having a flexor response to pain for the motor repsonse part of GCS?
Lesion above the red nuclei
32
What is the significance of a patient having a extensor response to pain for the motor repsonse part of GCS?
Deep cortical lesion below the red nuclei
33
What is the significance of a patient not having a response to pain for the motor repsonse part of GCS?
Severe damage to Brain stem and or cortex
34
What is the significance of a patient having a correct verbal response to a question for the GCS score?
Normal cortical function
35
What is the significance of a patient having a confused verbal response to a question for the GCS score? E.g giving the wrong day of the week
Diminished higher cortical function
36
What is the significance of a patient having an inappropriate verbal response to a question for the GCS score? E.g saying sandwich when asked the day of the week
Language centres have been damaged (cortical function impaired)
37
What is the significance of a patient having a non worded response like groaning or moaning response to a question for the GCS score?
Significant cortical damage where the brainstem is taking over
38
What is the significance of a patient having no verbal response to a question for the GCS score?
Severe damage to brainstem and or cortex
39
What is an electroencephalogram?
Measure electrical activity of the cerebral cortex from the scalp
40
What does an electroencephalogram measure?
Measures how synchronous neuronal activity is
41
When are the brains neurones most synchronous?
Non dreaming sleep Drugged or coma Essentially when there’s very little stimuli
42
When are the Brains neurones least synchronous?
When highly alert, waking or dreaming stage of sleep (REM)
43
How is highly synchronous neuronal/cortical activity represented on an electroencephalogram?
High amplitude and low frequency = synchronous
44
How is non synchronised neuronal/cortical activity represented on an electroencephalogram?
Low amplitude and High frequency
45
How is non synchronised neuronal/cortical activity represented on an electroencephalogram?
Low amplitude and High frequency
46
How does sleep occur?
Reticular activating system gets deactivated by the THALAMUS So cortical activity is reduced so sensory input is reduced Neuronal activity synchronises
47
Why do we need sleep?
Not completely understood: Rest and recover? Conservation of energy? Protection? Memory? Clearance of metabolites?
48
What system removes toxic metabolites from the brain?
Glymphatic system
49
Why is the glymphatic system important?
Removes harmful proteins Most active at night Lack of sleep can lead to Alzheimer’s due to toxic protein build up
50
What are the 2 types of sleep?
REM sleep Non REM sleep
51
What are the 2 types of sleep?
REM sleep Non REM sleep
52
How long does each REM - Non-REM sleep cycle last?
Both together is about 90mins
53
How can you describe the muscle tone in Non-REM sleep?
Reduced muscel tone but can still move (why you can jerk in night)
54
What type of activity are seen with the neurones in Non-REM sleep?
High voltage + Low frequency (synchronous)
55
How many stages of Non-REM sleep are there?
4
56
How can you describe the muscle tone in REM sleep?
Muscle paralysis and Atonia
57
Which part of the brain controls REM sleep?
Pons
58
What functions are preserved in REM sleep?
Eye movements and other cranial nerve function Autonomics (Penile erection and loss of Thermoregulation)
59
What is nocturnal bruxism? What causes it?
Grinding of teeth in sleep Facial nerve overly active in sleep causing teeth to grind
60
What waves are seen when awake with eyes open?
Beta waves irregular 50Hz
61
What waves are seen while awake with eyes closed?
Alpha waves - regular 10Hz
62
What waves are seen in Stage 1 of sleep?
Alpha and Theta waves at 5Hz
63
What waves are seen at stages 2+3 of sleep?
Theta, sleep spindles and k-complex
64
What are sleep spindles??
High frequency bursts coming from the thalamus
65
What are k complex’s?
Slow synchronous activity The intrinsic rate of the cortex
66
What waves are seen in stage 4 sleep?
Delta waves (regular 1Hz)
67
Label the EEG on slide 15
68
What is insomnia?
Inability to sleep Normally due to anxiety, depression or other mental or physical illness
69
What is narcolepsy?
Dysregulation of your circadian rhythm
70
What is sleep apnoea?
Temporary occlusion of the airway during sleep resulting in intermittent sleep
71
What is the defintion of brain death?
Damage to brainstem and cortex (flat EEG)
72
What is the defintion of coma?
Widespread brainstem and cortical damage Has disordered EEG patterns and no sleep wake cycle
73
What is the defintion of persistent vegetative state?
Cortical damage, the brainstem is fine but you have disordered EEG pattern, some eye movements and repsonse to stimuli
74
What is locked in syndrome/what causes it?
Occlusion of the basilar/pontine arteries leads to loss of function of the corticospinal tract Person cant move but can move their eyes and understand everything
75
Why can a patient with locked in syndrome still move their eyes?
The edinger Westphal nucelus in the midbrain is unaffected

Y2 - CNS (21 decks)

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