block 6 lecture 2 consciousness and brain acivity Flashcards
what is the medical definition of consciousness?
awar and responsive to surroundings
what happens in locked in syndrome?
Patient has awareness, sleep-wake cycles, and meaningful behaviour
but is isolated due to facial and body paralysis.
what happens in a minimally conscious state?
Patient has intermittent periods of awareness and wakefulness and displays some meaningful behaviour.
what happens in persistent vegetative state?
Patient has sleep-wake cycles, but lacks awareness; only displays reflexive and non-purposeful behaviour.
what happens in chronic coma?
Patient lacks awareness and sleep-wake cycles; only displays reflexive behaviour.
what happens in brain death?
Patient lacks awareness, sleep-wake cycles, and brain-mediated reflexive behaviour.
what are the most common causes of loss of consciousness?
Stroke (Haemorrhage/Thrombosis/Embolus), Cardiovascular, Diabetes, Drug induced (alcohol/other poison/overdose), Epilepsy, Head injury, Raised intracranial pressure (tumour/abscess), Dementia, Uraemia, Liver diseas
what is the glasgow coma scale based on?
eye response
verbal response
motor response
what is brain stem death?
irreversible loss of consciousness, ventilation and brain stem function
tests for brain stem death? 6
Pupil response Corneal reflex Vestibulo-ocular reflex (VOR) Cranial nerve motor response Cough/gag reflex Respiratory effort
what happens in pupil response?
light shone in eye
pupil should constrict
what happens in corneal reflex?
cotton wool stoked on eye
lots of pain receptors, should blink
what happens in vestibulo-ocular response?
ice water put in ears
eyes should flicker
what is the brain stem area responsible for consciousness?
reticular activating system
what is the RAS?
collection of nuclei in the midbrain
why is it called the diffuse reticular system?
projects to all areas of the brain
what are the 4 principle nuclei?
locus coeruleus
raphe nuclei
ventral tegmntum
cholinergic nuclei
where is the locus coeruleus located?
pons
what is the neurotransmitter in locus coeruleus?
noradrenaline
when is the locus coeruleus active?
during arousal
where is the raphe nuclei located?
mid brain
what is the neurotransmitter in raphe nuclei?
serotonin
when is the raphe nuclei active?
waking state
what is the function of the raphe nuclei?
pain inhibition, cardiac rhythm
what are the disorders of the raphe nuclei?
Depression, OCD
what are the disorders of the locus coeruleus?
anxiety, panic, PTSD
where is the ventral tegmentum?
midbrain
what is the neurotransmitter in ventral tegmentum?
dopamine
what is the ventral tegmentum involved in?
Involved in reward circuitry of the brain - reinforces pleasurable sensations, motivation, intense emotions
