Venous return flow
The venous return flow is the return flow of the blood via the veins to the heart . The heart sucks the blood out of the body back into the right atrium . The return flow depends on the pressure difference that prevails between the pressure in the venous vascular system and the right atrium.
A back flow of the sucked blood inside the heart is prevented by the valve action of the heart valves . In humans, due to the upright gait in the veins, most of the blood flows from bottom to top. A return flow of the "return blood" within the veins , e.g. B. in the heart pause, is prevented by the venous valves .
The blood used up by the metabolism flows back and is enriched with oxygen in the lungs and pumped by the heart through the arteries back into the organism , where the oxygen-containing blood is used for the metabolism. The blood circulation also serves to exchange heat. One blood circulation takes about 23 seconds in humans.
For humans, problems with the return flow of venous blood express themselves in z. B. thrombosis or heart (i.e. pump) weaknesses ( heart attack ), heart valves - or venous valve failure u. a.). In addition to the vascular (artery) constrictions , it can also, or in parallel, lead to cardiac or lung weaknesses, after which there may be less backflow of blood.
Individual evidence
- ↑ Meyer's Universal Lexikon Volume I , VEB Bibliographisches Institut Leipzig 1978 p. 304