Overview of Blood

ByRavindra Sarode, MD, The University of Texas Southwestern Medical Center
Reviewed/Revised Jan 2024
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    Blood is a complex mixture of

    The body contains about 5 to 6 quarts (about 5 liters) of blood.

    Blood performs various essential functions as it circulates through the body:

    • Delivers oxygen and essential nutrients (such as fats, sugars, minerals, and vitamins) to the body's tissues

    • Carries carbon dioxide to the lungs

    • Carries waste products to the kidneys for elimination from the body

    • Transports hormones (chemical messengers) to allow various parts of the body to communicate with each other

    • Carries components that fight infection

    • Carries components that stop bleeding

    Once blood is pumped out of the heart, it takes 20 to 30 seconds to make a complete trip through the circulation and return to the heart.

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