Arousal, Sleep + Consciousness Flashcards
Define arousal
Emotional state associated with a goal or avoiding something noxious/toxic usually goal orientated
Define sleep
The readily reversible sate of reduced responsiveness to + interaction with the environment
Define consciousness
Difficult to define mainly to do with awareness of internal + external world
What are the two main components needed for consciousness?
Functioning cerebral cortex
Reticular formation
What is the reticular formation?
Diffuse network of specialised interneurones running the entire length of the brainstem
How is the reticular formation divided?
Median, medial + lateral columns
How is the cortex and reticular formation connected?
Reciprocal excitatory projections
Forming positive feedback loop
What are the 2 components required for consciousness + their function in this
- Cerebral cortex: site where conscious thoughts arise**
- Reticular formation: circulatory that keeps cortex awake
Describe the outputs of the reticular formation to the cortex
Reticular formation sends cholinergic (excitatory) projections to 3 major relay nuclei:
- basal forebrain nuceli send excitatory cholinergic fibres to cortex
- hypothalamus sends excitatory histaminergic fibres to cortex
- thalamus send excitatory glutamatergic fibres to cortex
What fibres connect the basal forebrain nuclei to cortex?
Excitatory cholinergic fibres
What fibres connect the hypothalamis to cortex?
Excitatory histaminergic fibres
What fibres connect the thalamus to cortex?
Excitatory glutamatergic fibres
What is used to assess consciousness clinically?
GCS
Glasgow coma scale
What are the 3 components of GCS?
Eye opening
Motor response
Verbal response
Eye opening GCS scoring + what it suggests
- 4: spontaneous eye opening | normal cortical + brainstem function
- 3: response to speech | slightly reduced cortical function w functional brainstem
- 2 response to pain | impaired cortical function but brainstem preserved
- 1: no response | severe damage to brainstem +/- cortex
Motor response GCS scoring
What does it suggest?
- 6: obeys commands | normal function w connections between brainstem + auditory system
- 5: localises stimuli | diminished higher cortical function but in tact connections between sensory + motor cortex
- 4: withdraws to pain |still physiological response to stimuli
- 3: flexor response to pain |lesion above red nuclei
- 2: extensor response to pain | lesion below red nuclei
- 1: no response to pain | severe damage to brainstem +/- cortex
Verbal response GCS scoring
What does it suggest?
- 5: oriented in time/place | normal cortical function
- 4: confused conversation | diminished higher cortical function but language centres in tact
- 3: inappropriate words |language centre damaged
- 2: incomprehensible sounds | cortical damage with brainstem mediated groans
- 1: no response: severe damage to brainstem +/- cortex