CJH332H1 Lecture Notes - Lecture 16: Transient Ischemic Attack, Resting Potential, Cerebrovascular Disease
Lecture 16: Translational neuroscience limitation
Stroke
• Initiated by the lack of blood flow to an area of the brain known as Ischemia – lack of circulating blood deprives
neurons of oxygen and nourishment
• Hemorrhage – extravascular release of blood causes damage by cutting off connecting pathways, resulting in
local or generalized pressure injury as well as impaired blood flow in large areas of the brain
• Movement, sensation or emotions, speech, etc. controlled by affected area of the brain are lost or impaired
• Loss of function varies with location and extent/type of damage
Stroke risk factors (non-modifiable)
• Age – as you gain age, more susceptible/probability to having stroke
• Gender – men more susceptible to stroke and women more likely to die from strokes (recover more challenging)
• Race – cholesterol processing in African Americans
• Genetics – Fary’s disease (accumulating fat), sickle ell disease (clumping of blood), connective tissue disorders
Stroke risk factors (modifiable)
• Hypertension – increasing blood pressure very dangerous
• Obesity, oral contraceptive use, physical inactivity, smoking, heavy alcohol consumption, hypercoagulability,
hyperlipidemia (excess fat deposited on blood vessels), TIA (transient ischemic attacks highly lead to stroke)
At a cellular level – time
• Brain requires continuous supply of O2 and glucose for neurons to function
• If blood flow is interrupted
- Neuronal metabolism is affected within 30 seconds
- Metabolism stops in 2 minutes
- Cell death occurs in 5 minutes
• Blood flow in brain less than 40% - electrical function affected (response different)
• Blood flow less than 30% - electrical failure complete (ATP production decline → Na/K ATPase disruption)
• Blood flow in brain to specific area less than 5% - release of potassium and cell death of neurons in that area
- Cannot maintain resting membrane potential
Major categories of strokes
• TIA
• Thrombosis
• Embolism
• Global-Ischemic (large area of brain loose blood) or Hypotensive Stroke (lose blood pressure in large of brain)
Transient Ischemic Attacks (TIA)
• Temporary focal loss (not all blood) of neurologic function caused by ischemia (analogous to angina in CAD)
• Most resolve within 3 hours
• May be due to micro-emboli that temporarily block blood flow (can move around)
• A warning sign of progressive cerebrovascular disease (there is a problem in your blood vessels in your brain!)
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Document Summary
Loss of function varies with location and extent/type of damage. Stroke risk factors (modifiable: hypertension increasing blood pressure very dangerous, obesity, oral contraceptive use, physical inactivity, smoking, heavy alcohol consumption, hypercoagulability, hyperlipidemia (excess fat deposited on blood vessels), tia (transient ischemic attacks highly lead to stroke) At a cellular level time: brain requires continuous supply of o2 and glucose for neurons to function. Neuronal metabolism is affected within 30 seconds. Major categories of strokes: tia, thrombosis, embolism, global-ischemic (large area of brain loose blood) or hypotensive stroke (lose blood pressure in large of brain) Many types of stroke: thrombotic stroke cerebral thrombosis is a narrowing of the artery by fatty deposits called plaque. Plaque can cause a clot to form, which blocks the passage of blood through the artery. Can break off into embolus: embolic stroke embolus is a blood clot/other debris circulating in blood (cid:894)does(cid:374)"t ha(cid:448)e to (cid:271)e (cid:271)lood - plaque)
