Renal portal vein

from Wikipedia, the free encyclopedia

The renal portal vein ( Vena portalis renalis ) in birds , reptiles and amphibians has two fundamental differences to the other portal veins . On the one hand, it is paired, so both the right and left kidneys have a portal vein. On the other hand, it has a valve in birds that regulates the blood flow in the portal vein circulation. This valve ( valva portalis renalis ) closes under the influence of histamine and acetylcholine , while adrenaline opens .

Birds

The two large veins of the posterior part of the body ( external and internal iliac veins ) open into the renal portal vein . In addition, the coccygomesenteric vein (corresponds to the caudal / inferior mesenteric vein of mammals) is connected to the portal vein. When the valve is open, the blood from these veins flows directly into the posterior vena cava ( caudal vena cava ) due to the lower flow resistance .

When the portal valve is closed, this direct drainage path is blocked and the blood has to pass through a second capillary area:

  • via current reversal in the coccygomesenteric vein to the hepatic portal vein and thus the capillary area of ​​the liver
  • through the capillary area around the tubules of the kidney and from there via the renal vein into the caudal vena cava .

The portal vein is probably the regulation of uric acid - excretion .

Importance in veterinary medicine

The presence of a second capillary system in the kidney means that intravenous injections in animals with a renal portal vein system must not be made in the rear half of the body, as the relatively high concentration of the substance in the kidney tissue can lead to kidney damage or the drug in the first Kidney passage is largely excreted.

literature

  • Franz-Viktor Salomon (Ed.): Textbook of poultry anatomy. Fischer, Jena / Stuttgart 1993, ISBN 3-334-60403-9 .