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40.4: Components of the Blood - The Role of Blood in the Body

  • Page ID
    • Boundless
    • Boundless
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    The many roles of blood include delivering nutrients and oxygen to cells, transporting waste from cells, and maintaining homeostasis.

    Learning Objectives
    • Identify the variety of roles played by blood in the body

    Key Points

    • Blood plays an important role in regulating the body’s systems and maintaining homeostasis.
    • Other functions include supplying oxygen and nutrients to tissues, removing waste, transporting hormones and other signals throughout the body, and regulating body pH and core body temperature.
    • Blood is composed of plasma, red blood cells, white blood cells, and platelets.
    • Blood platelets play a role in coagulation (the clotting of blood to stop bleed from an open wound); white blood cells play an important role in the immune system; red blood cells transport oxygen and carbon dioxide.
    • Blood is considered a type of connective tissue because it is made in the bones.

    Key Terms

    • hydraulic: pertaining to water
    • coagulation: the process by which blood forms solid clots
    • homeostasis: the ability of a system or living organism to adjust its internal environment to maintain a stable equilibrium

    The Role of Blood in the Body

    Blood is a bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. The components of blood include plasma (the liquid portion, which contains water, proteins, salts, lipids, and glucose ), red blood cells and white blood cells, and cell fragments called platelets.

    Figure \(\PageIndex{1}\): Components of human blood: The cells and cellular components of human blood are shown. Red blood cells deliver oxygen to the cells and remove carbon dioxide. White blood cells (including neutrophils, monocytes, lymphocytes, eosinophils, and basophils) are involved in the immune response. Platelets form clots that prevent blood loss after injury.

    Blood plays an important role in regulating the body’s systems and maintaining homeostasis. It performs many functions within the body, including:

    • Supplying oxygen to tissues (bound to hemoglobin, which is carried in red cells)
    • Supplying nutrients such as glucose, amino acids, and fatty acids either dissolved in the blood or bound to plasma proteins (e.g., blood lipids)
    • Removing waste such as carbon dioxide, urea, and lactic acid
    • Immunological functions, including circulation of white blood cells and detection of foreign material by antibodies
    • Coagulation, which is one part of the body’s self-repair mechanism (blood clotting by the platelets after an open wound in order to stop bleeding)
    • Messenger functions, including the transport of hormones and the signaling of tissue damage
    • Regulating body pH
    • Regulating core body temperature
    • Hydraulic functions, including the regulation of the colloidal osmotic pressure of blood

    Medical terms related to blood often begin with hemo- or hemato- (also spelled haemo- and haemato-), which is from the Greek word α (haima) for “blood”. In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones.

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