A Stroke is the sudden death of brain cells due to lack of oxygen, caused by blockage of blood flow or rupture of an artery to the brain. Sudden loss of speech, weakness, or paralysis of one side of the body can be symptoms.

A suspected stroke may be confirmed by scanning the brain with special X-ray tests, such as CAT scans. The death rate and level of disability resulting from strokes can be dramatically reduced by immediate and appropriate medical care. Prevention involves minimizing risk factors, such as controlling high blood pressure and diabetes. Abbreviated CVA. Also known as cerebrovascular accident.

A stroke may occur if an embolism travels from another part of the body and lodges within an artery in the brain. When an internal arterial wall becomes damaged, various types of emboli can form, such as one derived from platlets, thrombotic, cholesterol, or mixed. In this example, an embolism is formed in the internal carotid artery, breaks loose, travels towards the brain and lodges in a cerebral artery. The blocked artery deprives the brain of oxygen, damaging the surrounding brain tissue. The result is a stroke.

The U.S. National Library of Medicine provides an animated video on Strokes that show the anatomy of body parts and organ systems and  and conditions affect them at the Medline Plus Site.