Blood pressure - the force with which blood circulates in the body pushes against the walls of blood vessels, it is one of the basic parameters of life. The blood pressure decreases as it passes through the arteries, arterioles, capillaries and veins. The term "blood pressure" for the most part relates to blood pressure, namely, the pressure in large arteries.
Measuring blood pressure is carried out using the apparatus of sphygmomanometer, invented by an Italian doctor Riva Rochchi. This so-called non-invasive method for determining blood pressure. Blood pressure, defined in such a device is expressed in millimeters of mercury. Although the modern sphygmomanometer for safety reasons do not use mercury, unit of measurement of blood pressure by tradition are millimeters of mercury (mm Hg)
Blood pressure is measured in two terms. This is the systolic (the so-called top) and diastolic pressure. Sometimes referred to as heart and kidney, respectively. The thing is that the systolic blood pressure is a measure of the efficiency of the heart, that is the force with which the heart of "pumping" blood. It should be noted that the increase in heart rate does not always cause increase in systolic blood pressure. It depends on the causes of heart palpitations.
Diastolic blood pressure is an indicator of blood vessel tone. That is, the pressure of blood on the wall of blood vessels during diastole, ie when the heart is "relaxed." Kidney, it is called, for the reason that governed normal renal function. For example, renal failure, that is, a state where there is fluid retention, diastolic blood pressure increases as the volume of blood in the vascular bed is increased, and consequently, increased blood pressure in the vessel walls.
A normal blood pressure is equal to 120/80 mmHg However, for some people it may be lower, reaching 90/60 mmHg
In children, these figures may be lower in older and older - higher, due to sclerotherapy (seal) blood vessels. The regulation of blood pressure
Blood pressure is regulated by hormones and some other factors:
Renin-angiotensin system. Renin is produced by the kidneys. His selection by the kidneys depends on the normal blood supply. In the blood of the renin angiotensin becomes. This hormone increases vascular tone. When renal ischemia, such as renovascular disease, renin release is increased, which leads to increased blood pressure.
Baroreceptor reflexes. Baroreceptors (receptors sensitive to the pressure of the blood) in various organs, depending on the pressure effect on the frequency and force of heart contractions, which leads to a change in pressure. Aldosterone. This hormone is the adrenal glands. He is responsible for the delay in the body fluids, and consequently also regulates blood pressure.
Thyroid hormones. These hormones regulate metabolism in general ogranizme, and hence blood pressure.
Increase in blood pressure
Increased blood pressure - hypertension - is of two types: primary and symptomatic. "Symptomatic hypertension" means that the pressure is high due to several causes: heart disease (acquired defects, arrhythmias), renal, endocrine glands, etc. On the primary (essential) hypertension, they say, when the cause of high blood pressure can not be found. This so-called essential hypertension.
What are the conditions and diseases lead to high blood pressure?
Heart disease: the aortic heart valve, certain congenital heart defects, heart arrhythmia. Kidney diseases: kidney disease, almost all are accompanied by an increase in blood pressure - pyelonephritis, glomerulonephritis, renovascular disease, and others. The mechanism of pressure increase is associated with an increased release of renin due to renal ischemia, as well as dysregulation of renal water balance in the body (because the kidneys are removing excess fluid).
Adrenal disease: increased adrenal function (Cushing's syndrome), pheochromocytoma (tumor of the adrenal glands, in which there is an increase secretion of adrenalin).
Thyroid disease: hyperthyroidism - thyrotoxic goiter. Thus except for high blood pressure, because of their increased metabolism observed increase in heart rate, sweating, irritability and other symptoms.
Under what conditions is reduced blood pressure?
Heart disease: stenosis (narrowing) of the aortic valve and some congenital heart defects.
Diseases of the adrenal glands: adrenal insufficiency.
Thyroid disease: reduced thyroid function - hypothyroidism (myxedema).
Blood pressure is reduced and in many infectious diseases. This is due to the fact that for the mass death of the cells of microbes in the blood get their waste products. This leads to a decrease in blood pressure due to the fact that lowered the tone of blood vessels. Allergic diseases: for example, anaphylactic shock. In the blood of so-called fall of biologically active substances (histamine, bradykinin, and others), which also reduce vascular tone.