Reptiles

In reptiles with a final exit to land and the development of a pulmonary type of respiration, completely displacing the branchial branch, the further development of the pulmonary circulation occurs, so that 2 circles of circulation develop: pulmonary and corporal. Accordingly, the ventricle begins to divide the incomplete septum into two sections – the right and left ventricles. In birds, mammals and humans, there is a complete separation of the heart by a septum into 2 ventricles, respectively, in two circles of blood circulation. Because of this, they have completely separated venous and arterial blood: the venous blood flows into the right heart, and the arterial blood flows to the left.

By the nature of the circulating fluid, the vascular system of humans and vertebrates can be divided into two sections: 1) the circulatory system — a system of tubes through which blood circulates (arteries, veins, microcirculatory sections and the heart), and 2) the lymphatic system — a system of tubes, but which is moving colorless liquid – lymph. In the arteries, blood flows from the heart to the periphery, to the organs and tissues, and in the veins to the heart.

The movement of fluid in the lymphatic vessels occurs in the same way as in the veins, in the direction from the tissues to the center. There are, however, significant differences between the nature of the discharge of substances by the venous and lymphatic vessels. Dissolved substances are absorbed mainly by the blood vessels, solids – lymphatic. Absorption through the blood is much faster. In the clinic, the entire system of blood vessels is called cardiovascular, in which the heart and blood vessels are isolated.