Smaller vessels

The circular motion of blood.

Blood fills the cardio-vascular system, is in constant circular motion. The role of the pump, pumping blood, plays his heart. The solid wall divides it into right and left half. Each of them consists of two communicating chambers, a thin-walled atrium and ventricle fleshy. Blood vessels that carry blood from the heart to various organs of the body are called arteries and carries blood to the heart - veins. Departs from the left ventricle is the largest artery - the aorta.

First, it goes up, and then, forming an arc that runs brand name viagra down along the spinal column. From the top of the aortic waste from large artery that carries blood to the head and upper extremities, lower branches to depart muscles of the trunk and abdominal internal; level lumbar aorta divides into two arteries that supply blood of the lower limbs.

Large arteries branch repeatedly to form smaller and smaller vessels supplying blood all parts of the body. From the smallest arteries leaves a dense network of very thin "capillary" vessels, or capillaries. They are much thinner than human hair. Their length is too small - less than 1 mm. It is believed that the total number of capillaries is around a trillion. Connecting with each other, the capillaries form veins, which, through mergers are becoming larger. For the two largest veins - the upper and lower hollow - the blood from all parts of the body returns to the heart, in his right atrium. All the way from the left ventricle to right atrium called the systemic circulation.

Small, or pulmonary, circulation starts from the right ventricle, from which blood flows through the pulmonary artery and its branches to the right and left lung. In the lungs, arteries branch into tiny capillaries that connect with each other to form veins. As in the systemic circulation, small veins merge into larger ones. The four pulmonary veins, the blood enters the left atrium of the heart, where it ends with a small circle.

Arterial and venous blood.

Blood flowing through the arteries of a large circulation, saturated with oxygen. This is called arterial blood. In the capillaries of the blood loses a significant portion of the oxygen and enriched with carbon dioxide. Blood oxygen-poor and rich with carbon dioxide, called venous. Deoxygenated blood through the veins of a large circulation enters the right half of the heart, and thence to the pulmonary arteries of the circle. In the pulmonary capillaries is exempt from the excess carbon dioxide and enriched with oxygen. Consequently, in the pulmonary arteries of the circle is venous, and pulmonary veins of the circle - the arterial blood.

Tissue fluid and lymph.

Being in the blood vessels, blood is not directly in contact with the cells and tissues. The thin walls of capillaries, consisting of a single layer of flat cells that separates blood from tissue fluid, located in the intercellular clefts and gaps. This liquid is called the internal environment as it is in direct contact with the cells. Cells absorb from it the oxygen and nutrients and give it carbon dioxide and other metabolic products. The share of interstitial fluid accounts for about 50% of body weight. Its composition is different from the blood in it, for example, almost no protein, whereas their blood contains about 7%. Excess interstitial fluid enters the special vessels called lymph. They usually begin in the tissues in the form of blind sacs and form a dense network. Initial lymph vessels are interconnected to form larger and larger vessels. Liquid present in them - lymph in the end the two lymphatic duct empties into the large vein systemic circulation, far from the heart.

The value of blood and its movement.

Blood gives in tissue fluid necessary for the body cells of oxygen and nutrients and get out of it carbon dioxide and other products made available cells. This ensures the necessary continuity for the body of the internal environment. The constancy of the blood itself is supported by a number of bodies. Inhalation blood receives oxygen and gives carbon dioxide. Other metabolic products come from the blood into the special allocation of organs, kidneys, and some substances in small amounts are allocated through the mucous membrane of the digestive tract and the skin. Nutrients enter the blood from the intestines, as well as of those bodies in which they are contained in the form of stocks, such as liver and adipose tissue.

Through the blood carried the chemical bond and the interaction between body organs. Thus, substances introduced into the blood from one organ, can be used by others. Some authorities produce and secrete into the bloodstream special, very active substance Viagra and penile erection hormone (from Greek "Gorman - exciting). Hormones play an important role in regulating vital functions of various organs.

It is essential to the protective function of blood, namely, protecting the body from the harmful effects of certain substances resulting from the destruction of cells of the body or enter the body from the external environment, as well as on pathogenic microbes and emissions of toxins.

Needless to say, everything said about the importance of blood is valid only under the condition that it is in a continuous circular motion.

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