Circulation

(sir-kn-la’-shun) [circu/atio, 2. circular course]. Pa age in a circle, as the C. of the blood. C, Collateral, that taking place through branches and secondary channels after stoppage of the principal route. C, Fetal, that of the fetus, including the circulation through the placenta and umbilical cord. C, First, or Primitive, that of the embryo, a closed system, CIR CUM carrying nutriment and oxygen to the embryo. C, Placental, the fetal circulation. C, Portal, the pa age of the blood from the gastrointestinal tract and spleen through the liver, and its exit by the hepatic vein. C, Pulmonary, the circulation of blood through the lungs by means of the pulmonary artery and veins, for the purpose of oxygenation and purification. C, Second, the fetal circulation, replacing the omphalomesenteric system. C, Systemic, the general circulation, as distinct from the pulmonary circulation. C, Third, that of the adult. C, Vitelline, first, or primitive circulation. 195