CAUSES OF HIGH AND LOW BLOOD PRESSURE

Causes of High Blood Pressure

Although tremendous amount of medical research has been carried out on the causes of high blood pressure in human beings, yet no definite answer has so far been derived. It is reasonably certain that there is no one single cause of hypertension or high blood pressure. Most doctors now believe that hypertension in man is due to a number of different underlying causes, the most important of which could be genetic factors such as heredity . Other causes also considered to predispose, a person to high blood pressure are hardening of the arteries, tension and stress, environment and personality, high salt diet and a tendency to overweight.

Predisposing Factors of High Blood Pressure:

Heredity

It has been generally accepted that heredity plays an important if not a major role in producing high blood pressure. The tendency to develop hypertension is greatly influenced by genetic factors. It has been observed that many patients of hypertension have atleast one parent who also has high blood pressure. Studies conducted in  various countries indicate that when one parent has hypertension, chances of their offspring having it are 25 percent. When both parents have hypertension, the risk factor for the children is nearly 90 percent.

Environment and Personality

A person’s emotional make-up and response to stress or tension has often been cited as a pre-disposing  factor to hypertension. Some people respond to life-situations more intensely of anxiously than others, Strong emotions such as fear, anxiety, anger or painful stimuli can raise an individual’s blood pressure. But the pressure usually goes back to normal when the stress is removed. In some individuals however, the pressure does not go down when the tension ends. In such persons the blood pressure is being continually raised in their daily lives and eventually may remain at a higher level.

Some researchers believe that the personality of an individual can predispose a person to hypertension. It has often been reported that a driving, forceful. emphatic person showing a strong sense of urgency, restlessness, even irritability has the potential hypertensive personality.

However, there is no definite evidence to show that high blood pressure is the exclusive purview  of the hypertensive personality. Hypertension has also been known to strike the meek, mild and quiet person.

High Salt Diet

This is an controversial point among medical researchers. There is a group of scientists who believe that salt intake is irrelevant where high blood pressure in concerned. On the other hand, there are scientists who believe that excessive salt intake  is directly related to high blood pressure.  Although it has not been proved conclusively, yet there is strong evidence from studies from different parts of the world, that any community that eats a high salt diet is at a greater risk from high blood pressure. For example , in countries like Japan and South Korea where the salt intake is traditionally high due to a diet of meat and fish preserved in salt, high blood pressure is a common phenomenon. To strengthen this observation it may be noted that there is a small, isolated community in Japan where salt intake is low and these inhabitants show on an average, low blood pressure. Also some primitive races whose diet contains little to no salt content, are known to have lower blood pressure. Since most natural foods contain some salt, it is difficult to asses the salt intake of a particular individual. Many people however consume too much salt and this may be due to modern convenience foods where salt may be added in excess for various reasons like stability, longer shelf life etc.

For the drug treatment for high blood pressure because available, most patients were put on a salt restricted diet as the only effecting way of reducing blood pressure. There is no real evidence that this helps, once high blood pressure has already been established; but it may reduce the tendency to aggravate blood pressure and other complications.

Overweight

Again, there is no hard evidence that a tendency to  overweight causes high blood pressure but it has been observed clinically that people who are overweight are more likely to suffer from hypertension than people underweight. In a statistical analysis for insurance companies on a large sample of over 5,00,000 lives, it was observed that persons who were overweight often showed blood pressure on the higher side and were not considered good insurance risks. Therefore, overweight persons with high blood pressure should take particular care as this combination is likely to be dangerous. In other study of blood pressure in USA, It was concluded that obesity and overweight greatly increase the risk of developing hypertension.

Age

Nearly 65% of all cases of hypertension occur between the age group of 45-60 years. No particular reason has been found why it is more marked in this age group. In general, older people tend to show high blood pressure more frequently than younger ones. It is also possible that this condition is detected more frequently in the older generation, as outward symptoms of high blood pressure take a long time to appear. But not all older persons have high blood pressure, so this condition is not the result of ageing.

Among men, incidence  of hypertension increases till the age of 50 and then levels off. Among women, the incidence of high blood pressure increases continually with age.

Tension and Stress

As mentioned earlier, strong emotions such as fear, worry, anxiety and anger cause stress and tension. Studies have shown that blood pressure rises because of this stress but is usually comes down again on removal of the tension. The possibility that long term stress may cause high blood pressure in certain individuals cannot be ruled out . Emotional upsets, tension, anxiety and chronic personal conflicts are all important factors in aggravating and even initiating high blood pressure. It has been observed that the average blood pressure of people on vacation is lower than in their normal working and domestic lives. There is also evidence that stress and prolonged anxiety may cause blood cholesterol to rise. Again chronic stress may increase dependance on alcohol and cigarette smoking or tabacco chewing, and this directly or indirectly contributes to undesirable habits which ultimately lead to various diseases.

Hardening of Arteries and Blood Pressure

Hardening of Arteries can lead to high blood pressure and if  neglected may further lead to serious trouble. In the disease called Arteriosclerosis, the process of “hardening” of the arteries start from an early stage. Changes begin to occur in the arteries from youth and it starts with deposits of fatty plaques of cholesterol forming on the thin inner walls of the arteries known as arheromatosis. The lining of the arteries over these fatty deposits is raised and later this lining is shed. Small, shallow ulcers are formed with fat at their base and still later calcium is deposited. Due to all these changes, scarring of the artery occurs and the artery becomes narrowed and hard – and thus , the term “hardening” of the arteries. The flow of blood passing through this artery consequently slows down. Occasionally, these fatty deposits may become so thick that they fill up the whole artery and thus choke off the flow of blood completely.

Smoking

Most medical practitioners agree that smoking is the major cause of illness and premature death. It is the nicotine in tobacco and cigarettes that is the main culprit. From a tobacco containing only 0.3 percent nicotine, the smoke may contain 8.5 percent nicotine. And each cigarette has about 1.0 gms of tobacco. Its smoke may contain anywhere from 5-9 mgs of nicotine and although filters claim to remove nicotine, they remove only a small fraction of it.

The immediate effect of smoking is the acceleration of heart rate, a steep rise in blood pressure and an increase in the amount of blood pushed out, with each heart beat. This results in an increase in the work-load of the heart. There are millions of little particles in the blood called platelets. These are damaged by nicotine and have been found to be liked with the hardening of the arteries. Further, nicotine increases the tendency of the blood to clot in the blood vessels. This tendency is aggravated in cases where hardening of the arteries has already taken place, thus further increasing the risk for a heart attack. Nicotine, also stimulates the production of chemical substances called catecholamines in special glands and nervous tissues. These catecholamines are  normally presents in the tissues but when they become excessive, they may have an adverse effect in the heart and blood vessels. These catecholamines increase the work and oxygen consumption of the heart, they also increase the heart rate and blood pressure and thus increase the irritability of the heart. Nicotine also stimulates the production of pitressin which may constrict coronary arteries, thus increasing blood pressure. Continued smoking also raises blood cholesterol as well as fatty acids which further predispose and individual to arteriosclerosis. Smoking cigarettes, bidis or even tobacco chewing are common. All are harmful and result in shooting up of the blood pressure and increasing the work-load of the heart. In a study conducted in India, it was noted that elevated blood pressure was 1.5 times more prevalent in tobacco chewers than in non-chewers of tobacco.

Alcohol Intake

There is some evidence to indicate that heavy drinking may cause of aggravate high blood pressure. Although alcohol is not a direct cause of coronary heart disease or stroke, there is no doubt that heavy drinkers are at high risk. Moreover, obesity is common in heavy drinkers because of the high calorie content of alcohol and also in cases where it increases the appetite.

Tea and Coffee

Sometime weakness of the kidney may also cause high blood pressure in an individual. This condition may be caused of aggravated by over-indulgence in tea, coffee of alcohol. Theses substances in excessive amounts irritate the fine structure of the kidneys and ultimately disturb the blood pressure. Tea subjected to long brewing is harmful. particularly when drunk without milk. The effects of tea are largely cumulative but can be reversed by clearing the choked kidney with certain fluids. When used carefully in small amounts, tea and coffee are beneficial but excessive amounts are detrimental to kidney action and may aggravate a tendency to high blood pressure.

The Pill Contraceptive

Contraceptive pills are a modern cause of high blood pressure among women. These pills contain hormones – oestrogen and progesterone. It has been shown to cause high blood pressure in women taking it for long periods. It is advisable, therefore, for the pill-users to have their blood pressure to checked every six months or so. If the blood pressure is raised during the use of pill, it usually comes back to normal on discontinuation.

Pregnancy and High Blood Pressure

Every pregnant woman does not develop high blood pressure. In fact doctors do not know why some pregnant women get high blood pressure while others do not. Yet high blood pressure in pregnancy calls for careful supervision because the doctor has to consider risks to both – the mother and the unborn baby. For most women mild high blood pressure is not a problem. They comfortably cob with it. But effect of pregnancy on women with a history of high blood pressure is a matter of great concern for the doctors. In a normal case of pregnancy, the first three months there will be no change, in the next three months there will rise in blood pressure and in the last three months the blood pressure will fall to normal or below normal. However, as a precaution all pregnant women are advised to see their doctors regularly.

High blood pressure in pregnancy not caused due to toxaemia  can be treated in much the same way as a non-pregnant women suffering from it. But there are some important differences. Detailed investigations, such as X-ray examination should be avoided until the baby is born. Doctors may prescribe as few drugs as possible, especially those which are known to be safe and the drugs which aim at weight reduction and salt restriction.

Low Blood Pressure

Where as chronic high blood pressure can be a serious problem, chronic low blood pressure is not a major problem although it is at times annoying and uncomfortable.

There are two main kinds of Low Blood Pressure:

1.Postural Low Blood Pressure

2.Nutritional Low Blood Pressure

Postural Low Blood Pressure

Usually low blood pressure does not pose any major problem but postural hypotension which comes on abruptly and it causes dizziness and sometimes giddiness, and can be troublesome. When a person springs up from a sitting or lying position, his blood vessels have to contract in order to maintain normal blood pressure in the new posture, and this process is carried out automatically by reflex action of the nervous system.

Nutritional Low Blood Pressure

This kind of Low Blood Pressure is due to unbalanced nutrition. This faulty nutrition allows the tissues forming the walls of the blood vessels to become overly relaxed and perhaps flabby or stretched, hence less oxygen and nutrients are supplied to the tissues. As a result, the person who low blood pressure suffers from fatigue, usually lacks endurance, is sensitive to cold and heat, requires more sleep than healthy individuals, develops a rapid pulse on exertion.

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