PAT 20A/B Lecture Notes - Lecture 1: Posterior Cerebral Artery, Middle Cerebral Artery, Cerebral Circulation
4 Mar 2019
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Document Summary
Winter week one: stroke (brain attack) & atrial fibrillation. Circle of willis: a circulatory anastomosis helps to equalize blood pressure within the brain and provides alternate routes for blood to reach brain tissue if an artery become occluded. Mechanisms of injury to the brain: hypoxic & ischemic injury: hypoxia (deprivation of oxygen) & impaired atp production in the brain. Glutamate transport mechanisms become immobilized causing extracellular glutamate to accumulate in addition intracellular glutamate is released from the damaged cell. Excess glutamate opens nmda channels producing an increase in intracellular ca++ leading to the calcium cascade. Results in the release of intracellular enzymes, protein breakdown, production of free radicals, lipid peroxidation, fragmentation of dna, and nuclear breakdown causing cell death. Also cytotoxic edema results in failure of na/k pump which results from a build up of lactic acid & other metabolites contributing to extracellular acidosis causing na & h2o to enter cell causing more cell death.
