How is the circulatory system? What organs consists of?

Among the main systems that make up the human body, a special place is occupied by the circulatory system. As the circulatory system before the 16th century for scientists remained a mystery. Above her decision worked such outstanding thinkers as Aristotle, Galen, Garvey and many others. All their discoveries are generalized into a harmonious system of anatomical and physiological concepts.

Historical reference

A special role in the formation of correct ideas about the organs from which the human circulatory system is made was played by the Spanish scientist Servetus and the English naturalist William Garvey. The first managed to prove that the blood from the right ventricle can get into the left atrium only through the network of blood vessels of the lungs. Harvey discovered the so-called large circle (closed) circulation. Thus, the question was raised whether the blood moves strictly along a closed system, or not. The circulatory system of man and mammals is closed.

It is also necessary to recall the works of the Italian doctor Malpighi, who opened the capillary circulation. Thanks to his research, it became clear how the arterial blood turns into venous and vice versa. How does this question consider anatomy? The human circulatory system is a collection of organs such as the heart, vessels and auxiliary organs - red bone marrow, spleen and liver.

Heart - the main organ of the circulatory system of man

Since ancient times, in all cultures without exception, the heart has been given a central role not only as an organ of the physical organism, but also as a spiritual receptacle for the person's personality. In the expressions "friend hearted", "whole heart", "heart sad" people showed the role of this body in the formation of emotions and feelings.

But let us return to the anatomy and physiology of the heart. It is a muscular hollow organ that is divided by an impenetrable septum into a left (cube-shaped, having an irregular shape) and a right (regular shape) part. It was the work of Servet and Harvey that refuted Galen's idea that there are special openings in the heart wall through which the liquid connective tissue moves from one half to the other.

In fact, the presence of holes in the cardiac septum is a severe pathology of development, which refers to heart defects. It is diagnosed in the first days of the baby's life, as when listening to a phonendoscope in the thoracic region, so-called noises are clearly heard (extraneous sounds that arise when mixing arterial and venous blood). This is a serious violation of blood circulation, and only recently it is susceptible to surgical treatment.

Rhythm of the work of the heart

The heart is often compared to a pump. Indeed, his main task is to pump blood. To do this, the middle shell of the organ is represented by a powerful muscle called the myocardium. The heart consists of the right and left auricles and two ventricles, also the right and left. Between each atrium and ventricle are valves.

In the left part it is a bicuspid arterial valve (DAK), and in the right - a tricuspid (tricuspid valve). The contraction and relaxation of the heart are called respectively a systole and a diastole. Blood is distilled in only one direction: from the upper parts to the ventricles, and from them into the corresponding arteries. So, from the left ventricle at its reduction the portion of blood with force is thrown out in an aorta, blood pressure in it nearby 105 mm / rt. Art. A powerful push, in accordance with the laws of physics, quickly spreads in the form of waves into the system of arteries. We perceive the heart rate as a pulse. It can be well felt on the wrist or carotid arteries.

Liquid tissue in the human body

Functions of transporting oxygen and nutrients, removing toxins and toxins, as well as producing antibodies, are performed by the circulatory system. Blood, the structure of which can be represented as a mixture of cells (leukocytes, erythrocytes and platelets) and plasma (liquid part), ensures the fulfillment of the above tasks.

In the human body, there are hematopoietic tissues, one of which is myeloid. It is the leader in the red bone marrow, is located in the diaphysis and contains stem (hematopoietic cells), which are the precursors of red blood cells, leukocytes and platelets.

Features of the structure of blood

The red color of the blood is due to the presence of the hemoglobin pigment. It is he who is responsible for the transport of gases dissolved in the blood, oxygen and carbon monoxide. It can have two forms: oxyhemoglobin and carboxyhemoglobin. Blood plasma is 90% water.

The remaining substances are proteins (albumins, fibrinogen, gamma globulin) and mineral salts, the main of which is sodium chloride. Formal elements of blood perform such functions:

• Erythrocytes - carry oxygen;
• Leukocytes, or white blood cells (neutrophils, eosinophils, T-lymphocytes, etc.), - participate in the formation of immunity;
• Platelets - help stop bleeding when the integrity of the walls of blood vessels (responsible for blood clotting).

The system of blood circulation of a person, thanks to various functions of blood, is the most important in maintaining the body's homeostasis.

Vessels of the body: arteries, veins, capillaries

To understand what organs the human circulatory system consists of, it is necessary to imagine it as a network of tubes having different diameter and wall thickness. The arteries have a powerful muscular wall, because the blood moves along them with high speed and high pressure. Therefore, arterial bleeding is very dangerous, as a result of which a person loses a large amount of blood in a short time. This can have fatal consequences.

The veins have soft walls, abundantly equipped with semilunar valves. They provide the movement of blood in the vessels only in one direction - to the main muscle organ of the circulatory system. Since the venous blood is forced to overcome the force of gravity to rise to the heart, and the pressure in the veins is low, these valves do not allow the blood to move back, that is, from the heart.

The network of capillaries with a microscopic diameter of the walls fulfills the main function of gas exchange. They receive carbon dioxide (carbon dioxide) and toxins from tissue cells, and capillary blood, in turn, gives the cells oxygen necessary for their life. In total, the body has more than 150 billion capillaries, the total length of which in an adult is about 100 thousand km.

A special functional adaptation of the human body, which provides a constant supply of organs and tissues with the necessary substances, is collateral circulation, which can be observed both in physiologically normal conditions and in complex disturbances of the system (for example, clotting of the vessel by a thrombus).

Great Circle Circulation

Let us return to the question of which organs the circulatory system of man consists of. Recall that the closed circle of blood circulation, discovered by Harvey, originates in the left ventricle and ends in the right atrium.

The aorta, as the main artery in the body and the beginning of a large circle of blood circulation, carries oxygen-enriched blood from the left ventricle. Through the system of vessels that leave the aorta and branched throughout the human body, the blood enters all parts of the body and organs, saturating them with oxygen, performing the functions of exchanging and transporting nutrients.

From the upper part of the trunk (head, shoulders, chest, upper limbs) venous blood, saturated with carbon dioxide, is collected in the upper vena cava, and from the lower half of the trunk into the lower vena cava. Both hollow veins flow into the right atrium, closing a large circle of blood circulation.

Small Circle Circulation

The circulatory system - the heart, the circulatory system - is also included in the so-called small (pulmonary) circulatory system. It was discovered by Miguel Servet in the middle of the 16th century. This circle starts from the right ventricle and ends in the left atrium.

Venous blood through the right atrioventricular aperture from the right atrium enters the right ventricle. From it on the pulmonary trunk, and then along the two pulmonary arteries - left and right - it enters the lungs. And despite the fact that these vessels are called arteries, the blood flows through them venous. It falls into the right and left lungs, in which there are capillaries, braiding alveoli (pulmonary vesicles, of which the lung parenchyma consists). Between the oxygen of the alveoli and the connective tissue, gas exchange takes place through the thinnest walls of the capillaries. It is in this part of the body that the venous blood becomes arterial. Then it enters the postcapillary venules, which coarsen up to 4 pulmonary veins. On them, arterial blood enters the left atrium, where the small circle of blood flow ends.

Blood circulation on all vessels occurs simultaneously, without stopping and not interrupting for a second.

Coronary circulation

What is the autonomous circulatory system, from which organs it consists and in what features of its functioning, scientists such as Shumlyansky, Bowman, Gis studied. They found that the greatest value in this system is coronary or coronary blood circulation, which is carried out by special blood vessels, braiding the heart and departing from the aorta. These are vessels such as the left coronary artery with the main branches, namely: anterior interventricular, enveloping branch and atrial branches. And also this right coronary artery with such branches: right coronary and posterior interventricular.

Blood without oxygen returns back to the muscular organ in three ways: through the coronary sinus, the veins entering the atrial cavity, and the smallest vascular branches that flow into the right half of the heart without even showing up on its epicardium.

Circle of the portal vein

Since in ensuring the internal constancy of the environment, the circulatory system is very important, from which organs the circle of the portal vein consists, natural scientists studied the large circle of blood circulation during the examination. It was found that from the gastrointestinal tract, spleen and pancreas, blood accumulates in the lower and upper mesenteric veins, which subsequently, joining, form a portal portal vein.

The portal vein, together with the hepatic artery, enters the gates of the liver. Arterial and venous blood in hepatocytes (liver cells) undergoes thorough cleansing and then into the right atrium along the inferior vena cava . Thus, blood purification is due to the barrier function of the liver, which is provided by the circulatory system.

What organs are the auxiliary system

The complementary organs include the red bone marrow, the spleen and the already mentioned liver. Since blood cells do not live long, about 60-90 days, there is a need to recycle old spent blood cells and synthesize young ones. It is these processes that provide the auxiliary organs of the circulatory system.

In the red bone marrow containing myeloid tissue, the precursors of the formed elements are synthesized.

The spleen, in addition to the function of depositing part of the blood that is not used in the circulation, destroys the old red blood cells and partially compensates for their loss.

The liver also recovers dead leukocytes, erythrocytes and platelets and stores blood, currently not involved in the circulatory system.

The article examined in detail the circulatory system, from which organs it is composed and what functions it performs in the human body.