Final answer:
A Cerebrovascular Accident (CVA) or stroke is a sudden loss of blood flow to the brain, usually due to a blockage or rupture in the arteries. It can cause lasting brain damage and loss of neurological function. The circle of Willis is a critical arterial structure that ensures continuous blood supply to the brain.
Step-by-step explanation:
A Cerebrovascular Accident (CVA), also known as a stroke, is defined as a sudden loss of blood flow to the brain. This disruption can be due to a blockage, such as a blood clot, fat embolus, or an air bubble, or a rupture in the brain's arterial network. The circle of Willis, an important structure at the base of the brain formed from branches of the internal carotid and vertebral arteries, plays a crucial role in providing a continual blood supply to the brain and helps protect against the interruption of blood flow. A stroke can cause irreversible damage or death to the brain cells due to the lack of oxygen and nutrients which leads to the loss of neurological functions.
There are two main types of strokes: ischemic stroke and hemorrhagic stroke. Ischemic strokes are caused by a blockage that cuts off the blood supply to the brain, while hemorrhagic strokes are due to a bleed from a ruptured vessel. The outcome of a stroke can vary widely depending on the location and severity, ranging from mild temporary deficits to significant permanent impairments or even death.