week 5 Flashcards
(50 cards)
whats an ishaemic stroke
a blockage that leads to the brain becoming deprived of blood, neural tissues quickly die if there is no blood supply
whats a vulnerable area of the brain
arachnoid matter
anterior cerebral artery supplies
frontal cortex and motor part of parietal area, more medial aspect
middle cerebral artery supplies
side of brain (temporal, frontal)
posterior cerebral artery supplies
occipital lobe and part of parietal
whats venous drainage
- venous sinuses in dura matter
- sinuses converge at back of skull to sigmoid sinus on each side
- sigmoid sinus to internal jugular vein
differences between anterior bleed and venous bleed
anterior bleed happens quickly
venous bleed happens slowly
whats the blood brain barrier
capillaries in most parts of the Brian are “tightly sealed” so many substances cannot cross freely from the blood into intercellular fluid in the brain
what can and cannot pass through he blood brain abrreir
can= blood gases, water, alcohol, anesthetics (lipid soluble) cannot= antibiotics, other drugs. Glucose and amino acids require protein carriers
what can make the blood brain barrie less effective
new born
brain inflammation may reduce effectiviesnes (capillaries become more “leaky”)
why doe the brain need blood
supply of oxygen (deprival of oxygen can cause irreversible damage)
supply of glucose (brain can not store on fuel or produce energy)
blood remove hydrogen produced by metabolism
how is blood flow maintained in the brain
if systemic blood pressure falls, arterioles in the Brian automatically bilateral to increase flow
if blood pressurises they constrict
what happens if a specific area of the brain is especially active metabolically
local increase in CO2 causes vasodilation- increase flow then carrels it away
defne stroke
a focal neurological impariemtn of sudden onset and lasting more than 24 hours and of presumed vascular origin
whats interacted mean
tissue the has died because its blood supply has failed
when part of the brain has did it undergos
liquefactive necrosis
whats an transient ischaemic stack (TIA)
occlusions of blood flow but when blood supply is spontaneously restored before any tissue death has occurred
symptoms disagree within 24 hours
risk factors for a stroke
increasing age hypertension heart disease high blood cholesterol levles diabetes smoking oral contraceptives and pregancey
two types of ischaemic strokes
thrombosis
embolism
whats a thrombosis stroke
obstruction of blood vessel by a blood clot forming locally
often associated with hypertension and diabetes meelitus
whats a embolism stroke
obstruction due to blood clot formed elsewhere in the body (usually the heart)
where’s the most common sport a blood clot form in an ishcemic stroke
thrombotic occlusion are arterial branch points
whats ischaemic penumbra
supplied with blood by collateral arteries, where interventions are most likely to be effective
whats necrosis
severe ishaemia to neurones and glial cells die to liquefactive necrosis
cells will be broken down by their own enzymes and tissue replaced with cerebrospinal fluid
