Alvarez- Cerebrovascular disease Flashcards
___________ in cerebral vessels can respond directly to changes in perfusion pressure
_________ when pressure increases
__________ when pressure drops
smooth muscle
contracts –> ^ pressure
relaxes –> drops
cerebral blood flow mean arterial pressure range
Higher pressure = ______
lower pressure = _______
60-150 mmHG
edema
ischemia
how much glucose does the brain consume
brain tissue uses 5.6 mg of glucose per 100g per minute
Brain vascular features: (describe) internal elastic lamina external elastic lamina elastic fibers adventitia endothelial cells (cells that line interior surface of blood vessels)
internal elastic lamina –> well developed
external elastic lamina –> none
elastic fibers –> few in tunica media
adventitia –> very thin
endothelial cells –> not fenestrated (perforations) , have tight junctions critical for BBB)
CBF (cerebral blood flow) is ____ ml/ min , but not uniform depends on metabolic requirements
750 ml/min
I think blood
gray matter –> ______ml/(90 or)100g/min
White matter –> ________ml/100g/min
70ml
20-25ml
how do you calculate cerebral perfusion pressure and what is normal?
mean arterial pressure (MAP) - ICP (intracranial pressure)
normal >70mmHg
how do you calculate MAP (mean arterial pressure)
MAP= Diastolic BP + 1/3 pulse pressure
usually 90 mmHg
what is the brains metabolic O2 consumption
3.5 mL/ 100gr of brain tissue
initial color of an infarcted brain
pale
within hours to days of a brain infarction (ischemic stroke the gray matter becomes ?
congested with engorged, dilated blood vessels and minute petechial hemorrhages
en embolus blocking major blood vessels recirculates into infarcted area it can cause a hemorrhagic infarction and may aggravate edema formation due to ?
disruption of the BBB
During stroke CPP falls casueing
an increase in dilation of cerebral blood vessels
there can be a decrease in CPP beyond the ability for brain to compensate resulting in decreased Cerebral blood flow
Molecular events during ischemic stroke
<50mL/100g per minute = ________
inhibition of protein synthesis
Molecular events during ischemic stroke
25mL/100g per minute = ________
protein synthesis ceases completely
Glucose utilization drops drmatically with the onset of anaerobic glycolysis –> tissue acidosis –> accumulation of lactic acid
Molecular events during ischemic stroke
10-23 mL/100g per minute = ________
variable tissue no function
Molecular events during ischemic stroke
16-18ml/100g per minute = ________
NEURONAL ELECTRIC FAILURE
Molecular events during ischemic stroke
10-12 mL/100g per minute = ________
failure of membrane ion homeostasis
Molecular events during ischemic stroke
<10 mL/100g per minute = ________
irreversible tissue damage
what is excitotoxicity
brain cells are over excited due to increased Ca++ influx causing activation of proteases and lipases , and formation of free radicals
80% of strokes are due to __________
20% are due to ______
ischemic cerebral infarction
brain hemorrhage
two types of edema caused by an ischemic stroke
cytotoxic edema
vasogenic edema
the faoilre of ATP dependent transport of sodium and calcium ions across the cell membrane resulting in accumulation of water and swelling of brain
cytotoxic edema (casued by stroke)
increased permeability or breakdown of the brain vascular endothelial cells that make up BBB, allowing macromolecules to enter extracellular space, causing an increased extracellular fluid volume
Vasogenic edema
Acute ischemic stroke subtypes are often classified in clinical studies using a system called
TOAST trial
what is the difference between thrombosis and embolism
thrombosis –> local in situ obstruction of artery due to disease of arterial wall
embolism –> particles or debris originating somewhere else that blocks arterial access to particular brain region