What brain dysfunction results when blood supply to a region (or regions) of the brain is blocked and vital brain tissue dies, as by a blood clot or a ruptured blood vessel?

Brain stroke (Cerebrovascular Accident)

Explanation:

The blood is supplied to anterior areas of brain by carotid arteries and to the posterior areas of brain by vertebral arteries. The dysfunction of brain after stroke depends upon the corresponding brain area associated with blocked artery. The middle cerebral artery (found in cerebrum portion of brain) is most commonly blocked in stroke.

Stroke occurs when brain cells are deprived of oxygen due to the lack of blood cell. There are several type of strokes. It may be caused by the blockage of blood vessels due to depositions of cholesterol in blood vessels. It hardened the walls of blood vessels and narrow them causing hindrance in the blood flow. If this clot remain at one place it is known as ischemic stroke and if it can convert to embolus and travel across the body it would cause the embolic stroke.

Haemorrhagic stroke is caused due to rupturing of one of the blood vessel and it is the most crucial form of stroke.

Ischemic stroke.

Explanation:

When the blood supply to parts of the brain is cut off, there is lack of oxygen supply to the brain tissues in that area and since brain tissues survive on oxygen for fuel, they begin to die off. This leads to ischemic stroke.

The cause of ischemic stroke may be as a result of the formation of a clot in the arterial walls called thrombus. This clot grows gradually and finally blocks off the artery completely.

Another cause may be from a clot called embolus, getting into the bloodstream and getting stuck in the arteries supplying blood to the brain.

Ischemic stroke leads to the loss of the part of the brain affected and the body systems and parts it is controlling. Paralysis and blindness are examples.