The Physics
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Volume of Blood in a Human

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Bibliographic Entry Result
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Taggart, Starr and Cecie Starr. Biology: The Unity and Diversity of Life. California: Wadsworth, 1989: 398. "On the average, an adult human male who weighs 70 kg. has a blood volume of about 5 liters, or a little more than 5 quarts." 5 L
"Blood." World Book Encyclopedia. Chicago: World Book, 1998: 407. "An adult who weighs 160 pounds has about 5 quarts (4.7 liters) of blood." 4.7 L
World Book Rush-Presbyterian-St. Lukes Medical Center Medical Encyclopedia 7th edition. Chicago: World Book, 1995: 120-121. "In an adult of average size there is a little less than 10 pints (4.7 l)." 4.7 L
"Blood." Encyclopedia Britannica. Chicago: Encyclopedia Britannica, 1973. "The body of an adult male contains about five litres of blood, that of a woman or a child less." 5 L
New Book of Popular Science. Connecticut: Grolier, 1996: 197. "In just a single day, the heart pumps the body's supply of blood-approx. 5 quarts (4.7 liters) in an average adult …." 4.7 L

In humans, blood is the fluid that transports nutrients and oxygen to every cell in the body. It also transports wastes away from cells. Blood keeps our body temperature steady by carrying excess heat from regions of the body to the skin where it can be dissipated. It also fights infection and carries chemicals that regulate many body functions.

Blood is composed of a yellowish fluid, called plasma, in which are suspended the millions of cells that constitute 45% by volume of whole blood. A cubic millimeter of human blood contains about 5 million red blood cells, or erythrocytes; 5,000 to 10,000 white blood cells or leukocytes; and 200,000 to 300,000 platelets or thrombocytes. The blood also carries many salts and organic substances in solution in the blood plasma.

In an average healthy adult, the volume of blood is about one-eleventh of the body weight. Most sources state the volume of blood in an average human adult, who is between 150 to 160 pounds, as between 4.7 and 5 liters, although the more recent sources state the volume of blood in an average adult as 4.7 liters. Sources state that an 80-pound child had about half that amount, and an 8-pound infant has about 8.5 ounces. People who live at high altitudes, where the air contains less oxygen, may have up to 1.9 liters more blood than people who live in low altitude regions. The extra blood delivers additional oxygen to body cells. The heart pumps all the blood in the body each minute when the body is at rest.

According to a source from 1973, the volume of blood can be measured one of two ways. Each depends upon putting a known quantity of some substance in the body, and, after it has been distributed uniformly in the whole circulating fluid, measuring the degree of dilution which has taken place. The substances most commonly used then were carbon monoxide, Evans blue dye, and radioactive chromium.

LanNa Lee -- 1998

Bibliographic Entry Result
(w/surrounding text)
Cameron, John R.; James G. Skofronick & Roderick M. Grant. Physics of the Body. Second Edition. Madison, WI: Medical Physics Publishing, 1999: 182. "Blood represents about 7% of the body mass or about 4.5 kg (volume ~ 4.4 liters) in a 64 kg (141 lb) person." 4.4 L

Editor's Supplement -- 2001

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