1. Blood 2007

2. Blood = specialized connective tissue Cells = 45% of blood Cells = 45% of blood –Erythrocytes (red blood cells, RBCs) –Leukocytes (white blood cells, WBCs) –Platelets Extracellular matrix of blood = Plasma; 55% of blood Extracellular matrix of blood = Plasma; 55% of blood 5-6 Liters total blood volume in adult 5-6 Liters total blood volume in adult

3. Functions of Blood Gaseous transport – RBCs carry oxygen and carbon dioxide Gaseous transport – RBCs carry oxygen and carbon dioxide Transport of metabolites and regulatory molecules (hormones) Transport of metabolites and regulatory molecules (hormones) Homeostatic regulation of body temperature, osmotic balance Homeostatic regulation of body temperature, osmotic balance Transport of cells and antibodies for defense and immunity Transport of cells and antibodies for defense and immunity

4. Erythrocytes Most numerous blood cells Most numerous blood cells Transport O 2 and CO 2 via hemoglobin Transport O 2 and CO 2 via hemoglobin Only cell in blood stream that remains in blood stream Only cell in blood stream that remains in blood stream Biconcave disk shape provides large surface area relative to volume, 8  m in diameter Biconcave disk shape provides large surface area relative to volume, 8  m in diameter Shape maintained by bendable cytoskeleton Shape maintained by bendable cytoskeleton In mammals, no nucleus, mitochondria, ER, ribosomes in mature RBCs. All expelled during development. In mammals, no nucleus, mitochondria, ER, ribosomes in mature RBCs. All expelled during development. 120-day life span; destroyed by macrophages in spleen and bone marrow. 120-day life span; destroyed by macrophages in spleen and bone marrow.

5. Erythrocytes

6. Relative Size of Blood Cells

7. Leukocytes = White Blood Cells Granulocytes = neutrophils, eosinophils, basophils Granulocytes = neutrophils, eosinophils, basophils –Numerous secretory vesicles in cytoplasm –2 or more lobes to nuclei –Typically short lived (a few days) –Die by apoptosis and scavenged by macrophages Agranulocytes = lymphocytes and monocytes Agranulocytes = lymphocytes and monocytes –Single lobed nuclei –Do NOT have abundant secretory vesicles –Circulate for a few days and then invade tissues and become macrophages –Rounded in shape when circulating, flattened and motile in tissues.

8. Leukocyte Cell Types NeutrophilEosinophil BasophilMonocyte Lymphocyte Platelets Granulocytes Agranulocytes

9. Neutrophils – 60-70% of circulating leukocytes Multi-lobed nuclei, 3-5 lobes Multi-lobed nuclei, 3-5 lobes Main function: phagocytosis and destruction of bacteria Main function: phagocytosis and destruction of bacteria Motile: large numbers exit the blood stream early in response to acute bacterial infections. Motile: large numbers exit the blood stream early in response to acute bacterial infections. Granules contain: lysozyme and other antimicrobial enzymes, collagenase plus others. Granules contain: lysozyme and other antimicrobial enzymes, collagenase plus others. In females, the nucleus has a drumstick (Barr body), contains the condensed, inactivated second X chromosome. In females, the nucleus has a drumstick (Barr body), contains the condensed, inactivated second X chromosome.

10. Eosinophils – 2-4% of circulating leukocytes 2-lobed nucleus 2-lobed nucleus Principal function: allergic and inflammatory reactions and parasitic infections Principal function: allergic and inflammatory reactions and parasitic infections Often found at sites of chronic inflammation, commonly in respiratory or digestives tracts Often found at sites of chronic inflammation, commonly in respiratory or digestives tracts Counteract the effects of basophils in allergic reaction: secrete histaminase which degrades the histamine secreted by basophils. Counteract the effects of basophils in allergic reaction: secrete histaminase which degrades the histamine secreted by basophils. Prominent eosinophilic granules (red/pink) Prominent eosinophilic granules (red/pink)

11. Basophils - <1% circulating leukocytes Involved in allergic and inflammatory reactions Involved in allergic and inflammatory reactions Bilobed nucleus Bilobed nucleus Basophilic granules (blue/black stained) obscure the view of the nucleus Basophilic granules (blue/black stained) obscure the view of the nucleus Secrete histamine (vasodilation) and heparin (anti-coagulant) Secrete histamine (vasodilation) and heparin (anti-coagulant)

12. Blood Cells

13. Lymphocytes – 20-25% circulating leukoctyes Variable in size, 6-18  m in diameter Variable in size, 6-18  m in diameter Single, round, heterochromatic nucleus Single, round, heterochromatic nucleus Agranulocyte Agranulocyte Function in immunity Function in immunity 2 classes, indistinguishable morphologically 2 classes, indistinguishable morphologically –B cells – humoral (antibody-mediated) immune response –T cells – mature in thymus, cell-mediated immune response

14. Monocytes – 3-8% circulating leukocytes Largest in size of circulating leukocytes Largest in size of circulating leukocytes Large, acentric kidney-shaped nucleus Large, acentric kidney-shaped nucleus Agranulocyte Agranulocyte Stay in circulation a few days and then migrate into connective tissue and differentiate into macrophages Stay in circulation a few days and then migrate into connective tissue and differentiate into macrophages As macrophages: phagocytize and destroy dead cells As macrophages: phagocytize and destroy dead cells

15. Platelets (Thrombocytes) Principal function: blood clotting Principal function: blood clotting Produced by megakaryocytes in bone marrow –bud off cytoplasm to form platelets. Produced by megakaryocytes in bone marrow –bud off cytoplasm to form platelets. 2  m in diameter (very small) and anucleate 2  m in diameter (very small) and anucleate 10-day life span 10-day life span

16. Relative #s of Leukocytes Neutrophil > Eosinophil >Basophil Monocyte > Lymphocyte > Platelets