Pathophysiology of stroke NRSG366.docx - Pathophysiology of stroke Stroke occurs when there is(1 ischemia(inadequate blood flow to a part of the brain

Pathophysiology of stroke NRSG366.docx - Pathophysiology of...

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Pathophysiology of stroke Stroke occurs when there is (1) ischemia (inadequate blood flow) to a part of the brain or (2) haemorrhage (bleeding) into the brain that results in death of brain cells. In a stroke, functions such as movement, sensation, thinking, talking, or emotions that were controlled by the affected area of the brain are lost or impaired. The severity of the loss of function varies according to the location and extent of the brain damage. Blood is supplied to the brain by two major pairs of arteries: internal carotid arteries (anterior circulation) and vertebral arteries (posterior circulation). The carotid arteries branch to supply most of the (1) frontal, parietal, and temporal lobes; (2) basal ganglia; and (3) part of the diencephalon (thalamus and hypothalamus). The major branches of the carotid arteries are the middle cerebral and anterior cerebral arteries. The vertebral arteries join to form the basilar artery, which branches to supply the middle and lower parts of the temporal lobes, occipital lobes, cerebellum, brainstem, and part of the diencephalon. The main branch of the basilar artery is the posterior cerebral artery. The anterior and posterior cerebral circulation is connected at the Circle of Willis by the anterior and posterior communicating arteries. The brain requires a continuous supply of blood to provide the O 2 and glucose that neurons need to function. Blood flow must be maintained at 750 to 1000 mL/min (55 mL/100 g of brain tissue), or 20% of the cardiac output, for optimal brain functioning. If blood flow to the brain is totally interrupted (e.g., cardiac arrest), neurologic metabolism is altered in 30 seconds, metabolism stops in 2 minutes, and cellular death occurs in 5 minutes. And that may result into stroke. Two types of stroke: ischemic and haemorrhagic stroke Ischemic stroke : An ischemic stroke results from inadequate blood flow to the brain from partial or complete occlusion of an artery. Ischemic strokes may be either thrombotic or embolic.
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