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Unformatted text preview: Mosier 1 Kristen Mosier BISC 230 TA: Young E. Yoo 4/4/08 Strokes Introduction “Every 45 seconds, someone in America has a stroke. About 700,000 Americans will have a new or recurrent stroke this year and over 163,000 of them will die (making it the third leading cause of death in the USA)” (St. Johns Hospital). Strokes, or “brain attacks,” are a type of cardiovascular disease which concerns the arteries to and from the brain. They occur when a blood clot blocks the passage of a blood vessel in an artery to the brain (ischemic stroke), or when a blood vessel ruptures and interrupts blood flow to a particular area of the brain (hemorrhagic stroke). When blood flow to an area of the brain is decreased, there is a deficit in oxygen and brain cells may die. When brain cells in that specific area die, the abilities controlled by that area may be affected (i.e. speech, memory and movement). How a victim of a stroke is affected depends on the location in the brain where the stroke occurred and how much of the brain is damaged. Types of Strokes Ischemic Stroke “The most common type of stroke occurs when blood is prevented from delivering the necessary nutrients and oxygen to the brain because of blockages in the arteries” (Caplan, Dyken & Easton 25). Ischemic strokes account for about three-quarters of all strokes and have different causes. Typically, symptoms will develop over a few minutes and get increasingly worse after a few hours or days. Symptoms include neurologic deficits such as problems with speech and Mosier 2 language, or paralysis on one side of the body. The two common types of ischemic strokes are thrombotic and embolic strokes. Thrombotic Stroke A thrombotic stroke occurs when blood flow through a cerebral artery is blocked by a clot that forms along the vessel wall. A disorder called atherosclerosis is usually the cause for this type of stroke. Atherosclerosis, sometimes called “hardening of the arteries,” begins when the inner lining of the blood vessels become injured; often because of high blood pressure. It is an “abnormal condition of the arteries in which a thick, rough deposit – plaque – forms on the inner wall of the arteries and gradually narrows the passageway so that blood flow is slowed” (Caplan, Dyken & Easton 28). When damage to an artery occurs from atherosclerosis, the artery will develop roughened spots which stick out into the bloodstream. Over time, plaque build-up will cause the passageway in the vessel for blood to pass through to become smaller and smaller. Blood clots may form over the roughened places, which will either reduce blood flow to the brain, or obstruct blood flow completely and cause a thrombotic stroke....
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This note was uploaded on 06/01/2008 for the course BISC 230LXG taught by Professor Mcclure,greene during the Spring '08 term at USC.
- Spring '08