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Monday, 20 July 2009 15:45 |
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It's normal during periods of physical activity for the heart to pump harder and faster and for the blood pressure to rise. The blood pressure falls back to normal at rest Also, blood pressure can rise during times of stress. (it's generally higher during the day than at night.) But in some people, blood pressure stays abnormally high, even when we're relaxed and at rest. In the great majority of these cases (95 per cent) the cause isn't known. It's possible that as we age, and in people whose arteries are progressively damaged by an unhealthy lifestyle, the arteries become less elastic and become narrowed. Then the heart has to pump harder to force blood through the narrowed arteries, forcing up the blood pressure.
We also know hypertension is more likely in people who have a lot of salt in their diet. Salt causes the kidneys to retain fluid and this is thought to raise the blood pressure. Because we don’t know exactly what causes it, this type of hypertension is sometimes called 'primary' or 'essential' hypertension.
In the other five per cent of cases, hypertension is a by-product of another disease process. This is known as 'secondary' hypertension. Kidney disease and some rare hormonal diseases of the adrenal glands can cause secondary hypertension.
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Hypertension Overview 
