Rhythmic continuous contractions of the heart muscle allow the blood to overcome the resistance that is created by the density of blood vessels in combination with its own viscosity. The difference in blood pressure is formed and maintained by the venous as well as arterial sections of the circulatory system. The formation of such a difference with the emergence of areas of low and high pressure is one of the main mechanisms according to 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 heart ventricles leads to the release into the vascular system of the next portions of oxygenated blood, which causes the formation of blood pressure.
The highest level of pressure is the movement of blood in the aorta, and the lowest - in veins of large diameter. During removal from the heart muscle, a decrease in blood pressure occurs, just as the movement of blood through the blood vessels slows down.
The ejection of blood into the arteries occurs in portions. Despite this, a continuous continuous blood flow is observed in the body. The explanation for this is the high elasticity of the vascular walls. When enriched blood comes from the heart muscle, the walls of the vessels come into a stretched state and, due to their elasticity, create conditions for the movement of blood in the direction of 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 heart 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 stable indicators of pulse pressure that indicate that the heart is functioning normally.
Pulse
Certain areas of the human body during palpation of the skin allow you to feel the rhythmic movement of blood through the vessels. This phenomenon is called a pulse, which is based on a jerky periodic expansion of the arterial walls under the influence of cardiac impulses.
Based on the number of pulse beats over a period of time, one can judge how effectively the heart muscle copes with the work assigned to it. You can feel the movement of blood through the vessels, the pulse, by pressing one of the large arteries to the bone through the skin.
Blood flow through the veins
The movement of blood in the vein cavity is distinguished by its own characteristics. Unlike arteries, the least elastic venous walls are notable for their small 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 paths to the heart requires it to overcome its own gravity and viscosity.
An important role in ensuring stable venous blood flow is played by auxiliary muscle contraction, which also takes a direct part in the blood circulation. Muscle contraction leads to compression of the veins filled with blood, which causes its 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 nerve effects. This phenomenon is called basal vascular wall tone. And based on the sensitivity of tissues to stretching, mechanical external influences, mobility of organs, muscle mass.
Basal tone along with heart contractions is responsible for the movement of blood through the vessels. The process of basal tone is expressed in different ways that conduct blood, unevenly. It is based on the reduction of smooth muscle epithelium, as well as the phenomena that contribute to the formation of vascular lumen while maintaining blood pressure, ensuring blood supply to organs.
The speed of blood flow through the vessels
The speed of vascular blood flow is an important indicator in the diagnosis of blood circulation. The lowest rate of blood movement is observed in the capillary network, and the highest - in the aorta. The action of this pattern carries the most important biological meaning, since the slow movement of blood enriched with oxygen and nutrients contributes to their rational distribution in tissues and organs.
Linear velocity of blood flow
Distinguish between linear and volumetric blood speed. An indicator of the linear velocity of blood flow is calculated based on the determination of the total cross section of the vascular system. The total cross section of the aggregate of the capillary network of the human body is hundreds of times greater than the lumen of the thinnest vessel - the aorta, where the linear velocity reaches its maximum value.
Taking into account the fact that more than two veins in the human body fall on one artery, it is not surprising that the total venous lumen is several times greater than the arterial. This, in turn, leads to a decrease in the speed of venous blood flow by almost half. The linear velocity in the vena cava is about 25 cm / min and rarely exceeds this value.
Volumetric blood flow velocity
The determination of the volumetric velocity of blood movement is based on the calculation of its total amount when performing a full 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 pathways always pass an equal amount of blood per unit time.
The time of the completed circuit is the period during which the blood manages to pass through the small and large circles of blood circulation. With healthy heart function and the presence of about 70-80 contractions per minute, the complete movement of blood through the vessels with the completion of the circuit takes about 22-23 seconds.
Active blood flow factors
The determining, i.e., the dominant factor, which provides the mechanism of blood movement through the vessels, is the work of the heart muscle. However, there is also a wide range of equally important auxiliary factors for ensuring blood flow, among which are:
- closed nature of the vascular system;
- the presence of a difference in pressure in the vena cava, 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;
- the presence of muscle, organ, intrathoracic pressure;
- activity of the respiratory system, which leads to the occurrence of a suction effect of blood.
Cardiovascular system
Healthy regulation of blood flow through the vessels is possible only with concern for the state of the heart and its training. During running training, the need for oxygen saturation of tissues increases significantly. As a result, to ensure the vital functions of the body, the heart has to pump a lot more blood than when the body is at rest.
In people leading an inactive, almost motionless lifestyle, the main causes of blood flow through the vessels are exclusively heart rate increase. However, constantly being in a stressful state, without activating auxiliary factors of blood movement, the heart muscle gradually begins to fail. This tendency leads to heart fatigue, when an increase in blood supply to tissues and organs occurs in short, short periods. Ultimately, the lack of activity of the whole organism aimed at moving blood leads to a noticeable wear of the heart.
Trained mobile people who are not strangers to regular physical activity, whether it is sports or activity due to work, have a powerful healthy heart. A trained heart muscle is able to provide stable blood circulation without fatigue for a longer period of time. Therefore, an active mobile lifestyle, a rational rational alternation of rest and physical activity significantly contribute to the strengthening of the heart and the cardiovascular system as a whole.