Movement in a regular or circuitous course, returning to the point of origin, as the circulation of the blood through the heart and blood vessels. See also circulatory system.
- antegrade c. — circulation in the normal direction of flow.
- artificial c. — is maintained in cardiopulmonary arrest by cardiac compression.
- collateral c. — circulation carried on through secondary channels after obstruction of the principal channel supplying the part.
- coronary c. — that within the coronary vessels, which supply the muscle of the heart.
- cutaneous c. — cutaneous vessels are innervated by sympathetic adrenergic vasoconstrictor fibers; vasodilation is an important mechanism for losing heat after the body has been warmed.
- enterohepatic c. — the cycle in which bile salts and other substances excreted by the liver in the bile are absorbed by the intestinal mucosa and returned to the liver via the portal circulation.
- extracorporeal c. — circulation of blood outside the body, as through a hemodialyzer or an extracorporeal circulatory support unit.
- fetal c. — circulation of blood through the body of the fetus and to and from the placenta through the umbilical cord. See also fetal circulation.
- hepatic c. — includes the hepatic arterial blood supply and the supply from the portal vein; drainage is via the hepatic veins to the caudal vena cava.
- lymph c. — see lymph.
- maternal c. — the circulation of the dam during pregnancy, including especially that of the uterus.
- micro-c. — see microcirculation.
- neonatal c. — circulation in the newborn immediately after birth; the umbilical vessels contract forcing blood into the fetal veins; the foramen ovale closes, the ductus arteriosus narrows and eventually closes at day 1 to 2 after birth.
- ocular c. — consists of the uveal and retinal blood vessels supported by the aqueous humor and vitreous body.
- placental c. — consists of the umbilical arteries, the vessels of the placenta proper and the umbilical veins; approximates the fetal corporeal circulation in volume.
- portal c. — a general term denoting the circulation of blood through larger vessels from the capillaries of one organ to those of another; applied especially to the passage of blood from the gastrointestinal tract, pancreas and spleen through the portal vein to the liver.
- pulmonary c. — the flow of blood from the right ventricle through the pulmonary artery to the lungs, where carbon dioxide is exchanged for oxygen, and back through the pulmonary vein to the left atrium. See also pulmonary circulation.
- splenic c. — flow of blood through the splenic artery and arterioles to either the capillaries, e. g. white pulp, or the highly permeable sinuses of the red pulp. Splenic venous blood drains into the portal vein and passes through the liver before re-entering the general circulation.
- systemic c. — the flow of blood from the left ventricle through the aorta, carrying oxygen and nutrient material to all the tissues of the body, and returning through the superior and inferior venae cavae to the right atrium.
- c. time — the time required for blood to flow between two given points. It is determined by injecting a substance into a vein and then measuring the time required for it to reach a specific site.
