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BLOOD

BLOOD . Chapter 18. “The River of Life”. Only fluid tissue in the body Average adult has approximately 5L of blood Blood serves as the body’s transport system: Delivers oxygen & nutrients to cells Carries away carbon dioxide and metabolic waste to lungs or kidneys for elimination

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BLOOD

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  1. BLOOD Chapter 18

  2. “The River of Life” • Only fluid tissue in the body • Average adult has approximately 5L of blood • Blood serves as the body’s transport system: • Delivers oxygen & nutrients to cells • Carries away carbon dioxide and metabolic waste to lungs or kidneys for elimination • Distributes hormones from glands to target cells • Transports disease fighting substances • Distributes body heat

  3. Components • Blood has both solid and liquid components • Categorized as connective tissue • Living blood cell (“formed elements”) are suspended in non-living fluid matrix called plasma

  4. Plasma • Liquid portion of the blood • 90% water, 8% plasma proteins & 2% hormones, vitamins, minerals and other dissolved substances • Aside from antibodies, plasma proteins are made by liver & serve a variety of functions • Albumin contributes to osmotic pressure, helping to keep water in blood stream • Clotting proteins reduce blood loss when a vessel is injured • Antibodies help protect body from pathogens • Composition kept relatively stable through various homeostatic mechanisms

  5. Formed Elements • Leukocytes (WBCs) • Largest • Least abundant • Erythrocytes (RBCs) • Slightly smaller • 99% of living blood • Thrombocytes (platelets) • Smallest • 2nd most abundant

  6. Erythrocytes • Flexible, biconcave discs that lack a nucleus and most organelles • Contain the iron-containing protein hemoglobin, which allows it to carry oxygen in the bloodstream for distribution to cells

  7. Overview of Leukocytes • Only “complete” cells in the blood (contain nuclei and standard organelles) • Form an “army” to defend the body against bacteria, viruses, parasites & tumor cells • Not confined to blood vessels like RBCs, can slip in/out, a process called diapedesis • Respond to chemicals emitted by damaged cells, positive chemotaxis, and move via amoeboid motion to area of need

  8. Leukocyte Levels • In leukocytosis, a high WBC count (above 11,000/mm3), usually indicates an infection • In leukopenia, a low WBC count, is commonly caused by anticancer drugs and corticosteroids • In leukemia, bone marrow becomes cancerous and WBCs are turned out rapidly • These cells are immature and incapable of carrying out disease carrying functions • Body becomes susceptible to pathogens

  9. Types of Leukocytes • Granulocytes: granule-containing WBCs • Eosinophils: absorb acidic stains, appear pink • Basophils: absorb basic stains, appear purple • Neutrophils: do not absorb acidic or basic stain well, appear slightly pink or purple • Agranulocytes: lack visible cytoplasmic granules • Lymphocytes: pale cytoplasm forms thin rim around large, deep purple-blue nucleus • Monocytes: often kidney shaped, abundant gray-blue cytoplasm & dark purple nucleus

  10. Granulocyte (WBCs) Functions • Neutrophils: active phagocytes; number increases rapidly during short-term or acute infections • Eosinophils: Kill parasitic worms; increase during allergy attacks; might phagocytyze antigen-antibody complexes and inactivate some inflammatory chemicals • Basophils: Granules contain histamine (vasodilator), which is discharged at sites of inflammation

  11. Agranulocyte (WBCs) Function • Lymphocytes: part of immune system; B lymphocytes produce antibodies; T lymphocytes are involved in graph rejection, fighting tumors and viruses, and activation of B lymphocytes • Monocytes: Active phagocytes that become macrophages in the tissue; serve as a long-term “clean-up team”; increase in numbers during chronic infections

  12. Thrombocytes (Platelets) • Initiate clotting cascade by clinging to broken area • Help control blood loss from broken blood vessels Video Clip

  13. Hematopoiesis (Blood Cell Formation) • Occurs in red bone marrow (myeloid tissue) • In adults, found mainly in flat bones of skull and pelvis, the ribs, sternum and proximal epiphyses of humerus and femur.

  14. Types of Blood Cells

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