Blood pressure.

David Marsh - -

Describe the lifestyle factors that contribute

To high blood pressure and how high blood

Pressure can be treated

The term blood pressure is used to describe pressure in the aorta. Blood pressure is at its highest when the ventricles contract (systolic pressure). The lowest (diastolic pressure) is when the ventricles relax. Blood pressure is measured in millimetres of mercury. For the average human the normal blood pressure are 120mm Hg for systolic pressure and 80mm Hg for diastolic.

A rise in blood pressure means the heart is overworking and this can put strain on the circulatory system. On the other hand a fall can effect the organs (e.g. kidneys). So it is very important blood pressure is kept within the normal limits.

High blood pressure is also called hypertension. It is a condition in which the blood pressure in the arteries is abnormally high. The pumping of the heart creates blood to move along and against the walls of the blood vessels, which are flexible enough to dilate or contract and therefore keep the pressure constant. Sometimes the blood vessels may lose their flexibility, or the muscles surrounding them may force them to contract. This results in, the heart pumping more forcefully to move the same amount of blood through the narrowed vessels into the capillaries, therefore increasing the blood pressure. Over time, the high pressure can damage the arterioles in such organs as the liver, kidney, or brain and can also weaken the overworked heart. This increases the risk of death from heart failure, kidney failure, or stroke.

There is no specific cause of high blood pressure, but there are several contributing factors. These factors include smoking, high salt intake, obesity, family history of high blood pressure, kidney disease and stress.

Smoking is not a major factor in high blood pressure and only raises blood pressure slightly. The nicotine in cigarettes restricts blood vessels and raises the blood pressure. This is because the heart has to work harder to pump blood to all parts of the body.

When the salt content of blood goes up, it attracts ...

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When the salt content of blood goes up, it attracts water from around cells into the blood to dilute it, otherwise the blood would be too salty. There is salt as sodium outside every cell in the body. When the salt content of the fluid around your cells goes up, it attracts water from the blood and swelling occurs. Our kidneys are responsible for regulating salt and water levels in the body. When salt and water levels increase around cells, the excess is drawn into your blood, which is filtered by the kidneys. When the kidneys don't function correctly, fluid builds up around cells and in the blood. If there is more fluid in the blood, the heart has to work harder and blood pressure can go up because there is more pressure on the walls of the blood vessels. The heart can get weaker or worn out from the extra work.

Obesity is strongly associated with having high blood pressure so it is very important to maintain a healthy weight. A weight increase of 10kg is associated with an increase in systolic blood pressure of 2-3mmHg. People who are overweight are 2 to 6 times more likely to develop hypertension. Also being obese may lower certain actions of insulin that open blood vessels and it may cause structural changes in the kidney and abnormal handling of sodium. It is also associated with alterations in the systems that regulate blood flow.

Genetic factors are thought to play a prominent role in the development of high blood pressure. Unfortunately, the genes for high blood pressure have not yet been identified. The current research in this area is focused on the genetic factors that affect the renin-angiotensin-aldosterone system. This system helps to regulate blood pressure by controlling salt balance and the tone - state of elasticity - of the arteries. Chromosomes 13 and 18 are responsible for housing the genes responsible for blood pressure regulation, although pinning down the range of specific genes involved in high blood pressure is more difficult.

Diseases of the kidneys can also cause high blood pressure. This is called renal hypertension because it is caused by a problem in the kidneys. One important cause of renal hypertension is the narrowing of the artery that supplies blood to the kidneys (renal artery). In younger individuals, usually women, the narrowing is caused by a thickening of the muscular wall of the arteries going to the kidney. The narrowed renal artery reduces the circulation of blood to the affected kidney. This loss of blood then stimulates the kidney to produce the hormones, rennin and angiotensin. These hormones, along with aldosterone from the adrenal gland, cause a constriction and increased resistance in the arteries throughout the body, which results in high blood pressure. In older individuals, the narrowing generally is due to hard, fat-containing plaques that are blocking the renal artery.

Even though stress is clearly related to elevated blood pressure, finding the exact cause of the stress is very difficult. This is because what is stressful for one person may be relaxing for another. Also anything that is going on in a persons life can contribute to stress e.g. work, money, family.

With milder forms of high blood pressure it is usually treated with a self-help regimen that includes a no-salt diet and a weight-reducing diet, stop smoking, taking up exercise, and the avoidance of stressful situations. If these do not work doctors will usually prescribe or sympathetic-nerve blockers. These generally act by decreasing heart output and minor resistance to blood flow. are the most commonly used of these drugs.

More severe high blood pressure often requires the use of drugs called , which dilate the arteries, therefore lowering the blood pressure. Once medical therapy for high blood pressure begins, it must continue for the rest of the patient's life.

Severe and immediately life-threatening high blood pressure usually requires hospitalisation and acute medical care.