Akademik

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Movements in a circle, or through a circular course, or through a course that leads back to the same point; usually referring to blood c. unless otherwise specified. [L. circulatio]

- assisted c. application of external devices to improve pressure, flow, or both in the heart or arteries.

- blood c. the course of the blood from the heart through the arteries, capillaries, and veins back again to the heart.

- capillary c. the course of the blood through the capillaries.

- collateral c. c. maintained in small anastomosing vessels when the main vessel is obstructed.

- compensatory c. c. established in dilated collateral vessels when the main vessel of the part is obstructed.

- cross c. c. to an animal or one of its parts from the c. of another animal.

- embryonic c. the basic plan of the c. of a young mammalian embryo, at first similar to that in aquatic forms, with an unpartitioned heart and conspicuous aortic arches in the branchial region; as gestation progresses, the arrangement of the major blood vessel s gradually approaches that of an adult, but the routing of blood through the heart, characteristic of an adult, cannot be attained until lung breathing begins at birth.

- enterohepatic c. c. of substances such as bile salts which are absorbed from the intestine and carried to the liver, where they are secreted into the bile and again enter the intestine.

- extracorporeal c. the c. of blood outside of the body through a machine that temporarily assumes an organ's functions, e.g., through a heart-lung machine or artificial kidney.

- fetal c. the c. which serves the fetus in utero, with the placental circuit responsible for supplying oxygen and nutritive material and for eliminating CO₂ and nitrogenous wastes. SEE ALSO: embryonic c..

- greater c. SYN: systemic c..

- hypophysial portal c. SYN: portal hypophysial c..

- hypothalamohypophysial portal c. SYN: portal hypophysial c..

- lesser c. SYN: pulmonary c..

- lymph c. the slow passage of lymph through the lymphatic vessels and glands.

- placental c. the c. of blood through the placenta during intrauterine life, serving the needs of the fetus for aeration, absorption, and excretion; also, maternal c. through the intervillous space of the placenta.

- portal c. 1. c. of blood to the liver from the small intestine, the right half of the colon, and the spleen via the portal vein; sometimes specified as the hepatic portal c.; 2. more generally, any part of the systemic c. in which blood draining from the capillary bed of one structure flows through a larger vessel(s) to supply the capillary bed of another structure before returning to the heart; e.g., the hypothalamohypophysial portal system.

- portal hypophysial c. a capillary network that carries hypophyseotropic hormones from the hypothalamus, where they are secreted into blood, to their sites of action in the anterior hypophysis. See portal c., pituitary gland, hypothalamus. SYN: hypophyseoportal system, hypophysial portal c., hypophysial portal system, hypophysioportal system, hypothalamohypophysial portal c., hypothalamohypophysial portal system (1).

- pulmonary c. the passage of blood from the right ventricle through the pulmonary artery to the lungs and back through the pulmonary veins to the left atrium. SYN: lesser c..

- Servetus c. obsolete eponym for the pulmonary c..

- systemic c. the c. of blood through the arteries, capillaries, and veins of the general system, from the left ventricle to the right atrium. SYN: greater c..

- thebesian c. (the-be′se-an) the system of smaller veins in the myocardium.

cir·cu·la·tion .sər-kyə-'lā-shən n the movement of blood through the vessels of the body that is induced by the pumping action of the heart and serves to distribute nutrients and oxygen to and remove waste products from all parts of the body see PULMONARY CIRCULATION, SYSTEMIC CIRCULATION