Body circulation

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Scheme of the blood circulation in humans:
red = oxygen-rich blood
blue = oxygen-poor blood

The circulatory system is the part of the bloodstream of humans and the cold blooded vertebrates that carries the blood through most of the body. That is why one speaks of the large cycle . Opposite it is the (small) pulmonary circulation , in which blood is transported in and out of the lungs .

The body's circulation begins with the expulsion of the oxygen-rich blood from the left ventricle into the large body artery , the aorta . All other major arteries branch off from the aorta . These divide into ever smaller arteries, finally into arterioles , which merge into the capillaries . The exchange of oxygen , nutrients and metabolic end products with the tissues takes place in them.

The capillaries go into the venules , fine blood vessels that collect the oxygen-poor blood after the exchange of substances. These connect to the comparatively larger veins, which finally flow into the superior inferior vena cava and the azygous vein. These two large veins carry blood back to the right atrium of the heart. In some places portal veins are still interposed in the veins .

The body circulation: left. Chamber - aorta - arteries - capillaries - veins - hollow veins - right. Forecourt

The pulmonary circulation: right. Chamber (oxygen-poor blood) - pulmonary arteries (oxygen-poor blood) - pulmonary capillaries (gas exchange) - pulmonary vein (oxygen-rich blood) - li. Atrium (oxygenated blood)


  • Neil A. Campbell, Jane B. Reece: Biology. 6th, updated edition. Pearson Studium, Munich et al. 2006, ISBN 3-8273-7180-5 .