Strokes Flashcards
ischemia
inadequate blood supply (including O2 and glucose)
prolonged ischemia results in ____
infarction (cell death)
anoxia
inadequate oxygen supply
what can cause a stroke?
- ischemia: result of occlusion (blocked a due to atherosclerosis or blood clot)
- hemmorrhage (bleeding a due to ruptured aneurism or hypertension)
- hypotension
what is the cause of the majority of strokes?
ischemia (caused by clotting)
what are the types of blood clots that cause ischemic stroke?
- thrombotic (eg. lacunar)
- embolic
when does a thrombotic stroke usually occur?
when a large artery to the brain is blocked by a blood clot (thrombus) that forms as a result of atherosclerosis
(occurs at site of formation)
atherosclerosis is a chronic inflammatory response where ____ and ____ are released
macrophages
neutrophils
the immune system releases ____ in response to inflammatory mediators of atherosclerosis, which function to…
cytokines
attract more white blood cells and perpetuate the cycle
in atherosclerosis, injured arterial walls fail to produce enough ____, which leads to…
- nitric oxide (maintains BV elasticity)
- arteries become calcified & lose elasticity
how does a thrombus form?
- atherosclerosis -> macrophages & neutrophils
- immune system -> cytokines
- injured walls -> insufficient NO -> calcified aa
- arterial walls stenose -> occlusion of blood flow
in atherosclerosis, arterial walls…
stenose: slowly thicken, harden & narrow until blood flow is reduced
Lacunar stroke
thrombotic stroke of small branches of large vessels that supply the brain
a lacunar stroke may cause…
clumsiness
weakness
emotional variability
(depending on branch affected)
an embolic stroke is usually caused by an ____
embolus: a dislodged blood clot that has traveled through the blood vessels, leading to embolic stroke
what are 4 possible causes of an embolus?
- atrial fibrillation: blood pooled in atria forms clots which break off and travel to brain as emboli
- artificial heart valves or heart valve disorders
- heart attack or failure
- emboli formed from fat particles, tumor cells, or air bubbles that travel through the blood stream (rare)
in a healthy brain, neurons are protected from exposure to blood by the ____
blood-brain barrier