Lec 7 Flashcards
ontogenetic period of development
synapse formation and pruning
myelination and glial cell formation
brain tumour (meningiomas)
between layers of meninges (protective layer) and are benign. only pain can cause is from the tumour putting pressure on other parts of brain.
brain tumour (gliomas)
develop from glial cells and infiltrate through the brain.
neuromas
tumour growing on one of cranial nerves
metastatic tumour
grow from cancerous cells carried from other organs to brain via blood stream
Stroke action plan
fast
face drooping
arm weakness
slurred language
time to call for help
also balance and vision problems
cerebral haemorrhage
bleeding in brain, vessel ruptures causing blood to seep into neural tissue
Aneurysn
balloon dilation form on wall of artery where elasticity is defective
cerebral ischemia
blockage in blood vessel disrupting blood supply to brain.
Thrombosis = blood clot
embolism = blockage from larger vessel to smaller one lodged.
arteriosclerosis = thickening of artery walls and channels narrow, restrict blood flow
what happens in ischemic stroke
blood vessel becomes blocked, neurons release excessive glutamate binding to NMDA receptor triggering excitatory response causing excess influx of positive ions to kill post synaptic neuron while spreading toxic cascade
TBI
closed head TBI - contusions (bruised brain)
subdural hematoma - collection of blood between dura mater and arachnoid membrane
mild TBI- no physical evidence, loss of consciousness, confusion,
CTE - dementia and cerebral scaring from multiple mTBIs
infections of the brain
Encephalitis - inflammation of brain
bacterial encephalitis - cerebral abscess (swollen area containing pus)
viral infections - rabies has affinity for neural tissue
neurotoxins
mercury
lead
endogenous neurotoxins e.g. cortisol when stressed
programmed cell death
apoptosis - genetic program for destroying themselves 1-2 days, orderly process
necrosis - passive cell death from injury, fast/disordered, neurons swell and break apart, cell scatters and can harm neighbouring cells
neurological diseases
epilepsy - repeated seizures generated by chronic brain dysfunction
focal seizures - neurons fire together only in focused region of brain, causes synchronous firing
absence seizure - no convulsions, loss of consciousness, staring into space, usually in children
parkinsons
degeneration of substantia nigra and deficiency in dopamine production. treated with L-dopa precursor to dopamine and can produce more to cover for deficiency
multiple sclerosis
attack myelin in CNS
autoimmune disorder where immune attacks myelin sheath. glial cells cannot re-myelinate those cells. can leave scar tissue
alzheimers disease
pathological change in brain.
neurofibrillary tangles - thread like tangles in Tau protein in cytoplasm on neurons
Particularly prevalent in amygdala and hippocampus
amyloid plaques - clump of scar tissue composed of degenerating neurons and beta-amyloid protein
neuron loss particularly in temporal lobe
alzheimers stages
prodromal stage- mild cognitive impairment, anxiety, autonomy is reduced
dementia stage - progressive loss of memory, deficits in attention, and personality changes
nervous system damage
no regrowth in CNS, adjacent neurons to the one who dies may also die.
In PNS axonal regrowth happens after injury
PNS axonal regrowth
when nerve damaged without damaging Schwann cell sheaths, axons regenerate to correct targets, if Schwann cell sheaths are separated off cell, axons regenerate incorrect sheaths and reach incorrect targets, if sheath completely displaced from cell, there is no functional regeneration
collateral sprouting
no regrowth in CNS, so adjacent neurons take up sites left open by spot where there is empty post synaptic neuron
neural reorganisation
cells connected to dead cell will reorganise themselves to have connection to region originally dedicated to degenerate cells (e.g. rat getting whiskers cut off)
release from inhibition with collateral sprouting
when one cell area in PNS overlaps with another is spot of inhibition, when one cell dies, not inhibited anymore and sprouts to the spot where the other cell used to be (e.g. Skin area A and B)
Recovery from TBI
usually happens immediately after due to reduction of swelling or dissipation of blood, but is hard to tell as people adapt without knowing
neurogenesis
stem cells produced in hippocampus and sub-ventricular zone, can migrate short distance and develop into neurons
phantom limbs
amputees continue to have experience of limbs that were lost, may attempt to use limb that was lost
