The familiar red fluid in the body that contains white and red blood cells, platelets, proteins, and other elements. The blood is transported throughout the body by the circulatory system. Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.
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The “circulating tissue” of the body; the fluid and its suspended formed elements that are circulated through the heart, arteries, capillaries, and veins; b. is the means by which 1) oxygen and nutritive materials are transported to the tissues, and 2) carbon dioxide and various metabolic products are removed for excretion. The b. consists of a pale yellow or gray-yellow fluid, plasma, in which are suspended red b. cells (erythrocytes), white b. cells (leukocytes), and platelets. SEE ALSO: arterial b., venous b.. [A.S. blod]
- arterial b. b. that is oxygenated in the lungs, found in the left chambers of the heart and in the arteries, and relatively bright red.
- cord b. b. present in the umbilical vessels at the time of delivery. It is of fetal origin.
- laky b. b. that is undergoing or has undergone laking. See lake (2), laky.
- occult b. b. in the feces in amounts too small to be seen but detectable by chemical tests.
- sludged b. b. in which the corpuscles, as a result of some general abnormal state, e.g., burns, traumatic shock, and similar stresses, become massed together in the capillaries, and thereby block the vessels or move slowly through them.
- venous b. b. which has passed through the capillaries of various tissues, except the lungs, and is found in the veins, the right chambers of the heart, and the pulmonary arteries; it is usually dark red as a result of a lower content of oxygen.
- whole b. b. drawn from a selected donor under rigid aseptic precautions; contains citrate ion or heparin as an anticoagulant; used as a b. replenisher.

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blood 'bləd n, often attrib
1) the fluid that circulates in the heart, arteries, capillaries, and veins of a vertebrate animal carrying nourishment and oxygen to and bringing away waste products from all parts of the body
2) a fluid of an invertebrate comparable to blood
3) blood regarded in medieval physiology as one of the four humors and believed to be the seat of the emotions
4) descent from parents of recognized breed or pedigree

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a fluid that circulates throughout the body, via the arteries and veins, providing a vehicle by which an immense variety of different substances are transported between the various organs and tissues. It is composed of blood cell, which are suspended in a liquid medium, the plasma. An average individual has approximately 70 ml of blood per kilogram body weight (about 5 litres in an average adult male).

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(blud) [L. sanguis, cruor; Gr. haima] the fluid that circulates through the heart, arteries, capillaries, and veins, carrying nutriment and oxygen to the body cells. It consists of the plasma, a pale yellow liquid containing the microscopically visible formed elements of the blood: the erythrocytes, or red blood corpuscles; the leukocytes, or white blood corpuscles; and the platelets, or thrombocytes. Called also haema [TA], hema, and sanguis [TA alternative].

Medical dictionary. 2011.