19 Brain Arousal Systems - B Flashcards

(45 cards)

1
Q

What are the 2 parts of conciousness

A

Arousal and awareness

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2
Q

What are examples of arousal

A

Sleep and wakefulness

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3
Q

What is a minimally conscious state

A

Reproducible evidence of awareness exists but communication is limited

Sleep wake cycles can be seen on EEG

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4
Q

What is a persistent vegetative state

A
  • pts eyes open and close
  • they can track objects
  • they can chew and swallow
  • do not respond to auditory stimuli, pain, hunger

Good example of arousal but no awareness

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5
Q

What is a coma

A

Deeply unconscious and displays unresponsiveness to stimuli

May display reflexes

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6
Q

What marks irreversible brain death

A

No EEG activity recorded

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7
Q

What is required for arousal and awareness

A

Cortical function

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8
Q

Disruptions in consciousness arise from

A

Subcortical lesions

  • brainstem
  • midbrain
  • hypothalamus
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9
Q

What are the excitatory amino acid arousal systems

A
  • reticular activating system (RAS)

- parabracial nuclei (PBN)

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10
Q

What are the cholinergic arousal systems

A

Pedunculopontine tegmental and laterodorsal nuclei (PPT/LDT)

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11
Q

What are the noradrenergic arousal systems

A

Locus coeruleus (LC)

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12
Q

What are the serotonergic arousal systems

A

Raphe nuclei (RN)

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13
Q

What are the dopaminergic arousal systems

A

Ventral tegmental area (VTA)

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14
Q

What does the RAS project to

A
  • hypothalamus
  • thalamus
  • cortex
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15
Q

What tract does the RAS descend to in spinal cord

A

Reticulospinal tract

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16
Q

What is the function of the RAS

A
  • regulates arousal and consciousness
  • all ascending (sensory) info goes through it
  • modal specificity is lost because all pathways are converged
  • USES GLUTAMINE
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17
Q

The ascending RAS has 2 outputs. Where do they go and what do they do

A

Ventral
-goes to cortex or through hypothalamus and then to cortex

Dorsal
-through thalamus and then diffuses to cortex

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18
Q

What is the parabrachial nuclei complex

A

Different neurons that play a role in promoting wakefulness through cortical activation \

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19
Q

What does the parabrachial nuclei do

A

Generates respiration patterns during waking state

  • amygdala activation of PBN causes hyperventilation during anxiety
  • USES GLUTAMINE
20
Q

What are the PBN outputs

A
Ventral pathway (like RAS)
-goes straight to cortex or through hypothalamus to cortex
21
Q

How is the PBN and RAS similar

A

Both use EAA glutamate

-RAS has interneurons that release GABA and ACh

22
Q

Excitable amino acids are crucial to

A

Baseline excitation of cortical activity

23
Q

What are the outputs of the PPT and LDT

A

Dorsal (to thalamus then cortex) or Ventral (to cortex or hypothalamus and then cortex)

24
Q

What is the major neurotransmitter over the PPT/LDT

25
What nuclei are the primary cause wakefulness and REM sleep
Cholinergic nuclei
26
Also involved in wakefulness and REM sleep (beside LDT/PPT)
- noradrenergic neurons of locus ceruleus - serotonergic neurons of raphe nuclei - histaminergic neurons of the tuberomammilary nuclei (of hypothalamus)
27
What does antihistamines inhibit in the brain
TMN network to make you drowsy
28
In addition to sleep, cholinergic neurons also
Provide baseline excitation that is crucial to cortical activity
29
What is the locus coeruleus
Noradrenergic neurons that function in the alerting response Being startled is also associated with this system
30
What are the functions of the locus coeruleus
- startle and alerting responses - sleep-wake cycles - behavioral vigilance
31
What are the ascending outputs of the locus coerulus
Dorsal and ventral pathways used by RAS Becomes the dorsal adrenergic bundle
32
What is the descending output of locus coeruleus
Sensory modulation
33
What are the outputs used by the RAS
Dorsal and ventral (same as RAS)
34
What does the raphe nuclei use
Serotonin (basis of SSRI anti-depressants)
35
What are the functions of the raphe nuclei
- quiet awareness - mood and affect - modulation of pain
36
The ventral tegmental nuclei uses what NT
Dopamine
37
The VTN provides input for
Cognitive functions Motor activity Emotions
38
Intracortical neurons relating to the RAS use GABA to create oscillations seen in the EEG as
Spindle-like discharges
39
Hyperpolarization of dorsal and ventral pathways occurs during
Low activity states like sleeping
40
During PVS (persistent vegetative state) cortical neurons are
Hyperpolarized Levadopa has been shown in some to increase cognitive function
41
During sleep, the thalamocortical neurons are __________ and occasionally show
Hyperpolarized; spindle-like discharges
42
Hyperpolarization of the thalamic arousal system shuts of
Cortex from the excitatory influence during deepest levels of sleep
43
Alertness is primarily done by what NT
Dopamine
44
Awareness is done primarily by what NT
Norepinephrine and serotonin (5HT)
45
Arousal is primarily done by what NT
EAA (glutamate) and ACh