Circles of human blood circulation: structure and role in the body

Blood is the constituent of the internal environment of the human body and the main transport system, because it functions not only its own, but also the cells of the immune system. Proteins of plasma transfer hormones, nutrients and oxygen to all tissues, and also provide maintenance of temperature homeostasis.

In this connection, blood circulation circles of a person, or more precisely, a functional system including the heart with the main vessels, arteries and veins of medium and small orders, and also the capillaries constituting the microcirculatory bed are distinguished. All of them have their own unique structure and mechanisms of regulation. Since in higher animals the heart is four-chambered, it is customary to distinguish between large and small circles of the person's blood circulation . Additionally, the brain and heart are also isolated because they have some peculiarities. For the first time, the discovery of general laws of this system was made by W. Harvey in the first half of the 17th century, and subsequently the data was replenished as the knowledge on anatomy and physiology was enlarged, explaining the hemodynamic and rheological properties of the blood, as well as the fine mechanisms of its motion along the vessels.

Structure

Circles of blood circulation a person could not exist without the central organ of this system - the heart. It is a hollow, to be more precise, a chamber, muscular organ, which, by force of its contractions, realizes, in fact, the dynamics of the blood flow. And in the future contribute to this and the vessels themselves, or rather, their muscular wall. A large circle of blood circulation in humans provides trophic and respiratory support to virtually the entire body: the trunk, extremities, and internal organs. Usually, the left common carotid artery (aa.carotis communis) and the brachiocephalic trunk (truncus brachiocephalicus), providing nutrition to the brain, depart from the arch of the aorta. Other branches of this main vessel, which begins in the left ventricle, are two subclavian arteries (aa.subclavia dexter and sinister), and then - axillary (aa.axillaris) and shoulder (aa.brachialis), supplying blood to the hands. Organs of the abdominal cavity, pelvis and lower extremities receive the trophic through the abdominal part of the aorta. The systemic blood flow ends with the lower and upper hollow veins flowing into the right atrium. Separate maintenance have easy, since. In the alveoli of this organ, one of the most significant processes occurs - gas exchange between capillaries and air sacs, during which blood coming from the left ventricle through the pulmonary trunk is enriched with oxygen and loses carbon dioxide. And then she returns to her heart in the left ventricle by vv.pulmonales. This system constitutes a small circle of the person's blood circulation.

Communication with other systems

Of course, the state of the heart and blood vessels is of great importance, since the speed and usefulness of trophism and respiration of all other organs and tissues depend on them. However, any systemic or local pathological processes in the body affect the circulation of a person and can cause atherosclerosis, arterial hypertension, increased stress on the heart. Therefore, for the normal functioning of this system, the overall health of the body is so important.