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The Structure, functions of the cardio-vascular system.

Cardio-vascular system is the complex of anatomical and physiological formations that provides the directed movement of blood and lymph in the organism of man and animals. It is necessary for the transport of gases in the tissues, substrata of nutrition and their metabolites. It is important in the process of metabolism and energy between the organism and the environment too.

The cardio-vascular system consists of the heart and blood vessels: blood and lymph.

The Central part of the cardio-vascular system is the heart pumping blood in the arteries.

According to their distance from the heart they become smaller and turn into arterioles and capillaries.

Blood constantly moves through the vessels. It makes all important vital functions, namely transport function (carring of oxygen and nutrition), protective (contains antibodies) and regulatory (contains enzymes, hormones and other biologically active substances). There are some different types of blood vessels in the cardio-vascular system: large and small arteries, large and small veins and capillaries.

The human heart is a hollow muscular organ. With the help of continuous vertical partition heart is divided into two parts: left and right. Running in a horizontal direction the second partition forms four cavities in the heart: the upper cavity - the atria, the lower ventricles.

In its activity the heart can be divided into two phases: systole (contraction) and diastole

(relaxation).

The heart rate per 1 min or the number of heart beats depends mainly on the functional state of wandering and sympathetic nerves. The heart of a healthy adult man makes from 60 to 72 beats per minute.

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