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2014-01-24 09:59:49
chapter 17
chap 17 1612
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  1. blood circulation
    • -initiated by the pumping of the heart 
    • -exits the heart via arteries, which branch until capillaris 
    • -by diffusing across the capillary walls, oxygen n nutrients leave the blood and enter the body tissue
    • -carbon dioxide n wastes move from tissue to bloodstream
    • -oxygen-deficient blood leaves capillary, it flows into veins which return it to the heart 
    • -then from the heart to the lungs than back to the heart
  2. blood composition
    • only fluid tissue in the body
    • -appears thick homogenous liquid but has both cellular and liquid components 
    • -is specialized type of connective tissue in which living blood cells (formed elements) are suspended in a nonliving fluid matrix (plasma)
    • -lacks collagen and elastic fibers, but dissolved fibrous protein become visible as fibrin strands during blood clotting
  3. erythrocytes
    • red blood cells that transport oxygen 
    • -normally constitute 45% of the total volume of a blood sample (hematocrit- blood frac)
  4. leukocytes and platelets
    • a thin whitish layer (buffy coat) is present at the erythrocyte-plasma junction
    • -white blood cells that act in various ways to protect the body
    • -cell fragments that help stop bleeding 
    • -account for 1%
  5. physical characteristics
    • -sticky, opaque fluid, metabolic taste
    • -depends on the amount of oxygen it carries, the colors vary 
    • -more dense than water and about 5% more viscous because of formed elements 
    • -slight alkaline, pH 7.35-7.45
    • 8% for the body weight ,5-6 L 1.5 gal in healthy adult male
  6. distribution functions
    • -delivering oxygen from the lung and nutrients from the digestive tract to all body cells 
    • -transporting metabolic waste products from cells to elimination sites ( lungs eliminate carbon dioxide and kidney to dispose of nitrogenous wastes in urine)
    • -transporting hormones from the endocrine organs to their target organs
  7. regulation functions
    • Maintaining appropriate body temperature by absorbing and distributing heat throughout the body and to the skin surface to encourage heat loss.
    • -Maintaining normal pH in body tissues. Many blood proteins and other bloodborne solutes act as buffers to prevent excessive or abrupt changes in blood pH that could jeopardize normal cell activities. Additionally, blood acts as the reservoir for the body’s “alkaline reserve” of bicarbonate ions.
    • -Maintaining adequate fluid volume in the circulatory system.Blood proteins prevent excessive fluid loss from the blood stream into the tissue spaces. As a result, the fluid volume in the blood vessels remains ample to support efficient blood circulation to all parts of the body.
  8. protection functions
    • -Preventing blood loss. When a blood vessel is damaged,platelets and plasma proteins initiate clot formation, halting blood loss.
    • -Preventing infection. Drifting along in blood are antibodies,complement proteins, and white blood cells, all of which help defend the body against foreign invaders such as bacteriaand viruses.