Blood pressure is the pressure in the blood vessels. Without it, it is impossible to fully implement the processes of metabolism in the tissues of the body. Thanks to him, blood moves through the circulatory system.
Arterial pressure is created inside the arteries, capillary, respectively, - inside the capillaries and venous - in the veins.
In addition, there is an osmotic pressureblood, it depends on the concentration of mineral salts in it. Its value usually remains stable. But even a minimal change can destroy blood cells. Sweat glands and kidneys respond to the neurohumoral regulation of osmotic pressure.
The size of the arterial blood pressure will affect:
- the power of contractions of the heart;
- the amount of blood he ejects at a time with each successive reduction;
- the resistance that the walls of the vessels (peripheral) exert to the moving flow of blood;
- the number of cardiac contractions per one accepted unit of time.
Secondary factors affecting the pressureblood, is its quantity and viscosity. And also this difference in pressure in the abdominal cavity and in the chest cavity, which arises in connection with movements during breathing.
The maximum blood pressure happens whenthe left ventricle of the heart decreases (systole). At the same time, about 70 ml of blood is expelled from it at a time. Through the capillaries and other small vessels such a quantity can not pass at once. The aorta, due to its elasticity, stretches, and systolic pressure also increases in it. In a person (healthy) older than 16 years, it can range from 110 to 130 mm Hg. Art.
During diastole, there are pauses between twocontractions of the left and right ventricles - the stretched walls of large arteries and aorta begin to contract. Thus, they push blood into the capillaries. Her pressure drops and at the end of diastole in the aorta drops to 90 mm Hg. st., and in arteries of large sizes - up to 70 mm Hg. Art. The difference between the indices of systole and diastole is perceived by a person in the form of a pulse.
The greater the distance from the blood vessels to the heart, the less pressure there is. The first, the upper figure indicates the pressure systolic, and the second, the lower, - on the diastolic.
In arteries large it is higher, in arterioles less. When you go to the capillary bed, blood pressure decreases, in the venous it falls even more, and in hollow veins it reaches even the negative values.
Measuring it in veins or capillaries is not technically very easy. Therefore, the magnitude of the pressure is judged on the basis of its definition in the arteries.
His indicators are normally dependent on how he livesa person than he does, which has individual characteristics. With age, the pressure value changes. It also increases with increased emotional stress, physical work. And at the same time, athletes, people who constantly and hard work physically, it can even decrease.
The systolic pressure in children is determined by the formula 80 + 2a, in which a is the age (the number of years).
The mechanisms that exist in the body and control the level of pressure, allow it to return to normal after minor fluctuations as a result of emotional stress or physical labor.
If they are violated, there is a steady change in its upward direction, then they speak about arterial hypertension, or downwards, then it is an arterial hypotension.
Usually any person knows his or her norm or rate of bloodpressure. And any deviation in this or that direction should serve as an occasion for the reference to the doctor, because there are a lot of reasons that affect this indicator. For example, in diseases of infectious, cardiac, poisoning often causes hypotension. And with kidney diseases, endocrine disorders - hypertension.
