Movement of blood through blood vessels. Mechanism and regulation of blood circulation

Rhythmic continuous contractions of the cardiac muscle allow the blood to overcome resistance, which is created by the density of the vessels in combination with its own viscosity. The difference in blood pressure is formed and maintained by the venous, as well as the arterial parts of the circulatory system. The formation of such a difference with the emergence of low and high pressure regions is one of the main mechanisms by which blood flows through the vessels.

Blood pressure

The functioning of the heart can be compared with the work of a kind of pump. Each rhythmic contraction of the cardiac ventricles leads to the release of regular portions of oxygenated blood into the vasculature, which causes the formation of blood pressure.

The greatest level of pressure differs the movement of blood in the aorta, and the smallest - in veins of large diameter. During the removal of the cardiac muscle, blood pressure decreases, just as blood movement along the blood vessels slows down.

The discharge of blood into the artery occurs portion by piece. Despite this, there is a constant continuous blood flow in the body. The explanation for this is the high elasticity of the vascular walls. When enriched blood flows from the heart muscle, the walls of the vessels come to an extended state and, due to elasticity, create conditions for the movement of blood towards the small vessels.

The mechanism of blood flow through the vessels is based on the occurrence of maximum pressure at the time of contraction of the cardiac ventricles. The minimum pressure is observed when the heart muscle relaxes. The difference between the maximum and minimum blood pressure is defined as the pulse pressure. It is the stable values of pulse pressure that indicate that the heart is working in the normal mode.

Pulse

Certain areas of the human body during palpation of the skin can feel the rhythmic movement of blood through the vessels. This phenomenon is called a pulse, based on the jerky periodic expansion of arterial walls under the influence of cardiac impulses.

Based on the number of heartbeats during a certain time, one can judge how effectively the heart muscle copes with the work assigned to it. To feel the movement of blood through the vessels, the pulse, it is possible, pressing through the skin one of the large arteries to the bone.

Blood transfusion through veins

The movement of blood in the cavity of the veins differs in its features. In contrast to arteries, the least elastic venous walls differ in insignificant thickness and soft structure. As a result, the movement of blood through small veins creates a slight pressure, and in veins of large diameter it is almost imperceptible or even equal to zero. Therefore, the movement of blood along the venous pathways to the heart requires overcoming its own severity and viscosity.

The most important role in providing stable venous blood flow is played by an auxiliary muscle contraction, which also takes a direct part in the circulation. Reducing the muscles leads to squeezing the veins, filled with blood, which causes her movement towards the heart.

Vascular tone

The structure of all vascular walls, with the exception of small capillaries, is based on smooth muscles, which are prone to contraction even in the absence of humoral or nervous influences. This phenomenon is called the basal tonus of the walls of blood vessels. And it is based on the sensitivity of tissues to stretching, mechanical external influences, organ mobility, muscle mass.

Basal tone along with cardiac contractions is responsible for the movement of blood through the vessels. Expressed the process of basal tone in different blood-conducting ways is not the same. It is based on the reduction of smooth muscle epithelium, as well as phenomena that contribute to the formation of the lumen of blood vessels while maintaining blood pressure, providing blood supply to organs.

Velocity of blood flow through blood vessels

The rate of vascular blood flow is the most important indicator in the diagnosis of blood circulation. The lowest velocity of blood movement is observed in the capillary grid, and the highest in the aorta. The effect of this pattern carries an important biological meaning, since the slow movement of oxygen enriched with oxygen and nutrients contributes to their rational distribution in tissues and organs.

Linear velocity of blood flow

There are linear and volumetric velocity of blood flow. The index of the linear velocity of blood flow is calculated on the basis of the determination of the total section of the vascular system. The total cross-section of the aggregate of the capillary grid of the human body is hundreds of times greater than the lumen of the thinnest vessel - the aorta, where the linear velocity reaches a maximum value.

Considering the fact that there are more than two veins per human in one artery, it is not surprising that the total lumen of the venous tract is several times greater than the arterial one. This, in turn, leads to a decrease in the rate of venous blood flow by almost half. The linear velocity in the hollow veins is about 25 cm / min and rarely exceeds this value.

Volumetric flow velocity

The determination of the volume velocity of blood movement is based on the calculation of its total number when performing a complete circle through the vascular system for a unit of time. In this case, the reasons for the movement of blood through the vessels are discarded, since any conductive paths always pass an equal amount of blood per unit time.

The period of completed circulation is the period for which blood can pass through small and large circles of circulation. With a healthy work of the heart and the presence of the order of 70-80 reductions per minute, the complete movement of blood along the vessels with the completion of the circuit occurs approximately for 22-23 seconds.

Factors contributing to active blood flow

The determining factor, i.e., the main factor, which is provided by the mechanism of blood movement along the vessels, is the work of the heart muscle. However, there is also a wide range of equally important auxiliary factors for blood flow, among which:

• Closed character of the vascular system;
• The presence of a difference in pressure in the hollow veins, vessels and aorta;
• Elasticity, elasticity of the vascular walls;
• The functioning of the valvular heart apparatus, which ensures the movement of blood in a single direction;
• Presence of muscular, organ, intrathoracic pressure;
• Activity of the respiratory system, which leads to the emergence of sucking effects of blood.

Exercise of cardiovascular system

Healthy regulation of the movement of blood through the vessels is possible only with the care of the condition of the heart and its training. During cross-country training, the need for oxygen saturation with tissues is significantly increased. As a result, to ensure the vital activity of the body, the heart has to pump a lot more blood in comparison to finding the body at rest.

In people who have a low-active, practically immobile lifestyle, the main causes of blood flow through the vessels are extremely rapid heartbeats. However, constantly being in a stressful state, without activating the auxiliary factors of blood movement, the heart muscle gradually begins to malfunction. This tendency leads to fatigue of the heart, when the increase in blood supply to tissues and organs occurs in brief, short periods. Ultimately, the lack of activity of the whole body, aimed at moving blood, leads to a noticeable deterioration of the heart.

Trained mobile people who are not stranger to regular physical activity, whether it is sports or activity due to work activity, have a powerful healthy heart. The trained cardiac muscle is able to provide stable blood circulation without fatigue for a longer period of time. Therefore, an active mobile lifestyle, a reasonable rational alternation of rest and exercise significantly contribute to strengthening the heart and the cardiovascular system as a whole.