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Fainting (cont.)

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Orthostatic hypotension

Blood vessels need to maintain their tone so that the body can withstand the effects of gravity with changes in position. When the body position changes from lying down to standing, the autonomic nervous system (the part of the brain not under conscious control), increases tone in the blood vessel walls, making them constrict, and at the same time increases the heart rate so that blood can be pumped upward to the brain. As people age, blood vessels may become less resilient, and orthostatic hypotension (relative low blood pressure with standing) may occur and cause syncope.

Vertebrobasilar artery disease

Blood vessels to the brain are no different than any other blood vessels in the body and are at risk for narrowing with age, smoking, high blood pressure, high cholesterol, and diabetes. While most people are aware of the carotid arteries that supply the thinking parts of the brain, another set of arteries supply the base of the brain. This vertebrobasilar system is also at risk for narrowing, and should there be a temporary disruption in the blood flow to the midbrain and the reticular activating system, fainting or syncope may occur. The vertebral arteries run to the brain in the back of the neck and are encased in bony tunnels. If blood flow in these arteries is disrupted, the brain stem and reticular activating system may turn off, causing syncope.

Medically Reviewed by a Doctor on 12/2/2013

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Fainting - Describe Your Experience Question: Please describe your experience with fainting.
Fainting (Syncope) - Treatments Question: What treatment has been effective for your fainting?
Fainting (Syncope) - Causes Question: What caused your fainting (syncope)?
Fainting (Syncope) - Symptoms Question: What symptoms did you experience with your fainting (syncope)?
Fainting (Syncope) - Diagnosis Question: After fainting, what medical tests and exams did you have? What was the diagnosis?
Source: MedicineNet.com
http://www.medicinenet.com/fainting/article.htm

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