circulation (sir-ku-la's hun). 1

Continuous motion, as of air; especially such motion in a definite circuit. 2. The motion of the blood through the ve els of the animal body (from the left ventricle of the heart through the arteries, capillaries, and veins, to the right auricle, thence to the right ventricle, and from there through the pulmonary ve els, to the left auricle and then the left ventricle again). 3. The transit of blood through the ve els of any single ti ue, region, or organ of the body (see subheadings). 4. The movements in or through organic bodies of fluids or substances other than blood — e. g., the contents of the stomach, or the non-excrementitious elements of bile. adult c. The c. (2d def.) which is established after birth, succeeding to the fetal c. allantoic c, allantoic! c. The c. (2d_ def.) through the ve els of the allantois. arterial c. The c. (2d def.) through the arteries, artificial c. The c. (2d def.) maintained artificially in cases of sudden impairment of the heart's action, as by placing the person in the recumbent posture, rubbing the limbs, etc. capillary c. The c. (2d def.) through the capillary ve els. The rate of this movement is variable, and not always in proportion to the number or force of the heart beats. cardiacopulmonary c. The adult c. c. of the blood. See c. (2d def.). c. of protoplasm. 1. The movement, in a steady current from place to place within the cell, of the granules imbedded in the threads of protoplasm. 2. The rotation of protoplasm, collateral c, compensatory c. The c. of blood through ve els which, being ordinarily small and of comparatively little importance, become enlarged to compensate for the complete or partial closure of the main ve els of a part, with which they communicate on both the proximal and the distal side of the obstruction. derivative c. A c. of the blood of certain parts (such as the nose, the ears, the ringers, the intestine, the parotid gland, the liver, etc.) from the arteries to the veins by means of small communicating ve els that are larger than capillaries, fetal c. The circulation in the fetus and the umbilical cord and placenta. greater c. See systemic c. lacunar c. A c. of blood or of a nutrient fluid through ve els whose continuity is interrupted by cavities in which, in many instances, organs are situated, le er c. See pulmonary c. nutrient c. The c. of blood in an organ for the purpose of nourishing the organ, as distinguished from the c. of blood in the same organ to be subjected to the physiological action of the organ, parietal compensatory c. The venous compensatory c. observed in the abdominal parietes in cases of obstruction.to the hepatic, placental c, placentary c. The c. (2d def.) of the fetal blood through the umbilical arteries, the capillaries of the villi, and, in the reverse direction, the fetal veins, on tbe one hand; on the other hand, the c. of the maternal blood through the uterine arteries, the inter villous lacunae, the uteroplacental sinuses, and back into the uterine veins, portal c. The c. through the portal vein and its capillaries, primary c, primitive c. See vitelline c. pulmonary c, pulmonic c. The c. of blood_ through the pulmonary ve els from the right ventricle to the lungs and back to the left auricle, return c. The backward motion of the blood to the heart in the systemic c. second c. See fetal c. systemic c. The c. of blood through the entire body except the lungs, third c. See adult c. uteroplacental c. The placental c. (q. v.) and that of the maternal blood in the uterine sinuses, considered as a whole, venous c. The c. of blood through the veins, vitelline c. The c. of blood through the ve els ramifying upon the surface of the vitelline sac. [Lat, circulatio.1