1. The Cardiovascular System: Blood

2. I. Overview of the Composition of Blood: The Hematocrit
Blood = vehicle for transport
Average blood volume
Women = 5.0 L
Men = 5.5 L
Components of blood
Plasma
Erythrocytes
Leukocytes
Platelets
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3. Hematocrit
Figure 15.2
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4. II. Plasma 90% water 6–8% proteins Electrolytes
Relatively high concentrations of Na+ and Cl-
Relatively low concentrations of H+, HCO3-, K+, and Ca2+
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5. Components of Plasma Table 15.1 (1 of 2)
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6. Components of Plasma Table 15.1 (2 of 2)
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7. III. Erythrocytes Oxygen and carbon dioxide transport
Life cycle of erythrocytes
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8. Hemoglobin Molecule Figure 15.3
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9. Hemoglobin Molecule Molecule = globin + 4 heme groups
Globin = 4 chains of polypeptides
Heme = an iron containing group
Greatly increases O2 transport
98.5% of transported O2 is bound to Hb
1.5% of transported O2 is dissolved in plasma
Also binds to CO2, H+, and CO
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10. Life Cycle of Erythrocyte
No DNA, RNA, or organelles
No division of mature RBCs
Short life span = 120 days
Replace 2–3 million RBCs/second
= 200 billion/day
Synthesized in red bone marrow
Erythropoiesis
Filtered by spleen (and liver)
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11. Erythrocyte Production
Erythrocytes and leukocytes develop from same stem cells in bone marrow
Hematopoietic stem cells
Erythrocyte synthesis stimulated by erythropoietin
Secreted from kidneys under conditions of low oxygen levels in blood flowing to kidneys
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12. Blood Cell and Platelet Production
Figure 15.5
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13. Erythrocyte Lifecycle
Figure 15.4
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14. Table 15.2
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15. Classification of Leukocytes
Granulocytes—cytoplasmic granules
Neutrophils—red and blue staining granules
Eosinophils—red staining granules
Basophils—blue staining granules
Agranulocytes—no cytoplasmic granules
Monocytes
Lymphocytes
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16. Neutrophil 50–80% of leukocytes in blood Phagocyte
Circulate in blood 7–10 hours
Migrate to tissues for a few days
Numbers increase during infections
Table 15.3 (1 of 5)
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17. Eosinophil 1–4% of leukocytes
Phagocytes (but not main mechanism of action)
Defend against parasitic invaders (e.g., parasitic worms)
Granules contain toxic molecules that attack parasites
Table 15.3 (2 of 5)
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18. Basophil <1% of leukocytes Non-phagocytic
May defend against large parasites by releasing toxic substances
Contribute to allergic reactions
Histamine
Heparin
Table 15.3 (3 of 5)
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19. Monocyte 5% of leukocytes Phagocytes
New monocytes circulate in blood few hours
Migrate to tissues and become macrophages
Wandering macrophages
Fixed macrophages
Table 15.3 (4 of 5)
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20. Lymphocyte 30% of leukocytes 99% of interstitial fluid cells
Three types
B lymphocytes (B cells)
T lymphocytes (T cells)
Null cells
Table 15.3 (5 of 5)
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21. B Cells B cells associated with antibodies
B cell contacts antigen  plasma cell
Plasma cell secretes antibodies (immunoglobulins)
Antibodies mark invaders for destruction
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22. T Cells Directly damage foreign cells
T cells contact infected, mutant or transplanted cells
Develop into cytotoxic T cells that destroy target cell
Takes several days
Secretory products form pores in target cell membrane
Lysis
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23. Null Cells Most are natural killer cells
Important against viral infections
Attack virus-infected cells—cause lysis
Fast acting—early immune response
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24. Blood Cell and Platelet Production
Figure 15.5
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25. Platelets
Cytoplasmic fragments derived from megakaryocytes, also called thrombocytes
Figure 15.5
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26. Platelet Components Colorless Cell fragments
No nucleus
Has organelles and granules
100,000 – 500,000 / mL blood
Important in blood clotting
Granules containing secretory products
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27. Platelet Secretory Products
ADP
Serotonin
Epinephrine
Chemicals for blood coagulation
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28. Platelets Are Sometimes Sticky
Platelets can adhere to surfaces under certain circumstances
Adhere to damaged blood vessel walls
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29. Formation of a Platelet Plug
Figure 15.6a
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30. Preventing the Spread of a Platelet Plug
Chemicals that prevent platelet aggregation
Prostacyclin (PGI2)
Produced in healthy endothelial cells
Nitric oxide
Released by healthy endothelial cells
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31. Preventing a Platelet Plug
Figure 15.6b
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32. Formation of a Blood Clot
Figure 15.8
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33. Coagulation Pathways Figure 15.9
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34. Clotting Factors Clotting factors produced by liver
Secreted into blood in inactive form
Activated during cascade
Plasma without clotting factors = serum
Hemophilia = genetic disorder, deficiency in clotting factor, usually Factor VIII
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35. Also Necessary for Clot Formation
Calcium (factor IV)
Platelet factor 3 (PF3)
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36. Factors Limiting Clot Formation
Anticoagulants
Proteins in plasma and surface of endothelial cells
Tissue factor pathway inhibitor
Secreted by healthy endothelial cells
Inhibits extrinsic pathway
Thrombomodulin
Binds to thrombin, forming complex that activates protein C
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37. Requires another cascade initiated by exposure of collagen
Dissolving Clot
Requires another cascade initiated by exposure of collagen
Plasminogen
Plasmin
Dissolves Clot
plasminogen activators
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38. Plasminogen Activators
Convert plasminogen to plasmin
Example: Tissue plasminogen activator
Secreted by endothelial cells during clot formation
Activated by fibrin
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39. Role of Coagulation Factors in Clot Formation Disorders
Hemophilia
Genetic disorder caused by deficiency of gene for specific coagulation factor
Von Willebrand’s disease
Reduced levels of vWf
Decreases platelet plug formation
Vitamin K deficiencies
Decreased synthesis of clotting factors
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40. Aspirin as an Anticoagulant
Low doses—anticoagulant
Inhibits formation of thromboxane A2
High doses
Inhibits formation of prostacyclin
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