circulation time

time (tīm) a measure of duration. Symbol t.

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activated partial thromboplastin time  (APTT) (aPTT) (PTT) the period required for clot formation in recalcified blood plasma after contact activation and the addition of platelet substitutes; used to address the intrinsic and common pathways of coagulation.

bleeding time  the duration of bleeding after controlled, standardized puncture of the earlobe or forearm; a relatively inconsistent measure of capillary and platelet function.

circulation time  the time required for blood to flow between two given points.

clotting time , coagulation time the time required for blood to clot in a glass tube.

inertia time  the time required to overcome the inertia of a muscle after reception of a stimulus from a nerve.

one-stage prothrombin time  prothrombin t.

prothrombin time  (PT) the rate at which prothrombin is converted to thrombin in citrated blood with added calcium; used to assess the extrinsic coagulation system of the blood.

reaction time  the time elapsing between the application of a stimulus and the resulting reaction.

stimulus-response time  reaction t.

thrombin time  (TT) the time required for plasma fibrinogen to form thrombin, measured as the time for clot formation after exogenous thrombin is added to citrated plasma.

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circulation time,

the time required for blood to flow from one part of the body to another. Timing a particle of blood involves injecting a traceable dye or radioisotope into a vein and timing its reappearance in an artery at the point of injection. Alternatively, a substance that can be tasted, such as saccharin, can be injected and the time it takes to travel to the tongue noted. The resulting time helps determine problems with heart failure and decreased cardiac output.

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circulation

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.

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antegrade circulation

circulation in the normal direction of flow.

artificial circulation

is maintained in cardiopulmonary arrest by cardiac compression.

collateral circulation

circulation carried on through secondary channels after obstruction of the principal channel supplying the part.

coronary circulation

that within the coronary vessels, which supply the muscle of the heart.

cutaneous circulation

cutaneous vessels are innervated by sympathetic adrenergic vasoconstrictor fibers; vasodilation is an important mechanism for losing heat after the body has been warmed.

enterohepatic circulation

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 circulation

circulation of blood outside the body, as through a hemodialyzer or an extracorporeal circulatory support unit.

fetal circulation

circulation of blood through the body of the fetus and to and from the placenta through the umbilical cord. See also fetal circulation.

hepatic circulation

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 circulation

see lymph.

maternal circulation

the circulation of the dam during pregnancy, including especially that of the uterus.

micro-circulation

see microcirculation.

neonatal circulation

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 circulation

consists of the uveal and retinal blood vessels supported by the aqueous humor and vitreous body.

placental circulation

consists of the umbilical arteries, the vessels of the placenta proper and the umbilical veins; approximates the fetal corporeal circulation in volume.

portal circulation

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 circulation

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 circulation

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 circulation

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.

circulation 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.