The Cardiovascular System: The Blood

  1. Blood Volume
    •Blood accounts for approximately 8% of body weight

    •Young female: 4-5 liters

    •Young male: 5-6 liters

    •pH of blood is 7.4
  2. Functions of Blood

    –Respiratory gases (O2, CO2, nitric oxide)





    –Body temperature


  3. Composition of Blood
    •Blood is composed of plasma (55%; 91% H2O), and formed elements (45%)

    •The formed elements of blood include:

    –Red blood cells (RBCs; erythrocytes)

    –White blood cells (1%)


    •Other components (~2%):

    –Electrolytes, hormones, gases, nutrients, wastes
  4. Red Blood Cells
    •Red blood cells (RBCs) are also known as erythrocytes

    •RBCs have biconcave shape (7-8 µm)

    •RBCs contain hemoglobin, which gives the blood red color

    •Mature RBCs do not contain nucleus or organelles
  5. Hemoglobin
    •In each RBC there are approximately 200-300 million molecules of hemoglobin

    • •Hemoglobin is composed of four globin chains, each
    • attached to a heme group

    • –Each heme contain Fe2+ that reversibly
    • combines to oxygen molecule

    •Hemoglobin can attached to four oxygen molecules to form oxyhemoglobin
  6. Process of RBC formation is called

    –RBC formation begins in the red bone marrow from hematopoietic stem cells

    –Reticulocytes- immature RBCs

    •Reticular count <0.5%- low rate of erythropoiesis

    •Reticular count >2%- high rate of erythropoiesis

    •Life span of RBCs is approximately 120 days

    –Aged, abnormal or fragmented RBCs are cleaned up by macrophages, by phagocytosis

    –As hemoglobin is broken down, amino acids, iron and bilirubin are released
  7. White Blood Cells
    •White blood cells (WBC; leukocytes)

    •1mm3 of normal blood contains 5000-9000 leukocytes



    –~65% of total WBC count

    –Highly mobile, phagocytic cells

    –Cytoplasmic granules contain lysosomes
  8. Granulocytes

    –2-5% circulating WBCs

    –Numerous in lining respiratory and digestive tracts

    –Weak phagocytes

    –Provide protection against parasitic worms

    Phagocytize antibody-antigen complexes


    –0.5-1% of circulating WBCs

    –Cytoplasmic granules contain histamine and heparin

    –Function: Involved in inflammatory and allergic reaction
  9. Lymphocytes
    –Account for 25% of circulating WBCs

    –Smallest of the WBCs

    • –T Lymphocytes- directly attack infected or cancerous
    • cell, transplanted cells

    • –B Lymphocytes- produce antibodies against specific
    • antigens

    Natural killer cells
  10. Monocytes
    –Largest leukocytes (12-20µm)

    –Highly phagocytic cells

    »Granules contain lysosomes

    –Differentiate into macrophages


  11. Formation of WBCs
    • •Both, granulocytes and agranulocytes mature from
    • hematopoietic stem cells

    • –Neutrophils, eosinophils, basophils originate in bone
    • marrow

    –Most lymphocytes and monocytes develop from hematopoietic stem cells in lymphatic tissue

    Leukopenia- abnormally low levels of WBCs
Card Set
The Cardiovascular System: The Blood
human anatomy