1.62 Consciousness Flashcards
Which part if the brain mediates arousal?
Upper Brainstem and Hypothalamus
What are the functions of the reticular formation?
Cranial nerve activity - interneurons Slow pain modulation Voluntary Movement ANS activity Distribution of monoaminergic and cholinergic ascending pathways Respiration Sleep Cerebral cortical arousal and wakefulness
What is ARAS?
Ascending Reticular Activating System
• No longer a monolithic unit
• Not only confined to the brainstem
Influence descends to the spinal cord as well as ascending to the cerebral hemisphere
What is the function of the ARAS?
not only for maintenance of wakefulness. Also a wide range of interrelated functions!
Mood, motivation, attention, learning, memory etc…
What releases Noradrenaline?
Locus Cerulous and Lateral Tegmental Area
What is the function of the Noradrenaline?
Attention, Cortical Arousal, sleep-wake cycle, learning and memory, anxiety and mood
Increases brain responsiveness and speeds info processing
What releases serotonin?
Raphe nulcues - medulla, pons and brainstem
What is the function of serotonin?
Spinal cord - modulation of slow pain
Thalamus - sleep-wake cycles, control of mood and certain types of behaviour - aggression
What releases acetylcholine?
Pontomesencepohalic reticular formation
Midbrain
Pons
What is the function of acetylcholine?
Excitability of thalamus, cortical excitability, memory and learning
What is brain death?
Complete and irreversible cessation of all cortical and brain stem activity
What could cause brain death?
• Trauma
• Intracranial hemorrhage
Hypoxic-ischemic injury from cardiac arrest
Widespread cerebral necrosis & edema, herniation, increased Intra Cranial Pressure and the complete absence of cerebral blood flow
What are the confirmation tests of brain death?
EEG - complete absence of brain wave
Angiogram - absence of intracranial blood flow
Radiostope cerebral imaging - absence of cerebral perfusion
Transcranial doppler - A velocity profile showing systolic spikes with absent or reversed diastolic flow
How is brainstem death confirmed?
Potentially reversible things must have been ruled out
State due to depressant also must be ruled out
Exclusion of reversible causes of apnoea should also be ruled out
What tests can be done to confirm brainstem death?
Absence of brain stem reflexes Pupils are fixed No corneal or oculomotor reflex No cough reflex Apnoea test No motor reflexes
