Chapter 19, part 1

1. Chapter 19, part 1 Blood

2. Learning Objectives • List the components of the cardiovascular system and explain the major functions of this system. • Describe the important components and major functions of the blood • List the characteristics and functions of red blood cells. • Describe the structure of hemoglobin and indicate its functions. • Discuss red blood cell production and maturation.

3. Learning Objectives • Explain the importance of blood typing and the basis for ABO and Rh incompatibilities. • Categorize the various white blood cells on the basis of structure and function. • Describe the structure, function and production of platelets. • Describe the reaction sequences responsible for blood clotting.

4. SECTION 19-1The Cardiovascular System: An Introduction

5. The cardiovascular system • Provides a mechanism for rapid transport of nutrients, waste products, respiratory gases and cells

6. SECTION 19-2Functions and Composition of Blood

7. Blood • Fluid connective tissue • Functions include • Transporting dissolved gases, nutrients, hormones, and metabolic wastes • Regulating pH and ion composition of interstitial fluids • Restricting fluid loss at injury sites • Defending the body against toxins and pathogens • Regulating body temperature by absorbing and redistributing heat

8. The composition of blood • Plasma and formed elements comprise whole blood • Red blood cells (RBC) • White blood cells (WBC) • Platelets • Can fractionate whole blood for analytical or clinical purposes

9. Figure 19.1 The Composition of Whole Blood Figure 19.1a

10. Figure 19.1 The Composition of Whole Blood Figure 19.1b

11. Figure 19.1 The Composition of Whole Blood Figure 19.1c

12. Hemopoiesis • Process of blood cell formation • Hemocytoblasts are circulating stem cells that divide to form all types of blood cells • Whole blood from anywhere in the body has roughly the same temperature, pH and viscosity

13. SECTION 19-3Plasma

14. Plasma • Accounts for 46-63% of blood volume • 92% of plasma is water • Higher concentration of dissolved oxygen and dissolved proteins than interstitial fluid

15. Plasma proteins • more than 90% are synthesized in the liver • Albumins • 60% of plasma proteins • Responsible for viscosity and osmotic pressure of blood

16. Additional Plasma Proteins • Globulins • ~35% of plasma proteins • Include immunoglobins which attack foreign proteins and pathogens • Include transport globulins which bind ions, hormones and other compounds • Fibrinogen • Converted to fibrin during clotting • Removal of fibrinogen leaves serum

17. SECTION 19-4Red Blood Cells

18. Abundance of RBCs • Erythrocytes account for slightly less than half the blood volume, and 99.9% of the formed elements • Hematocrit measures the percentage of whole blood occupied by formed elements • Commonly referred to as the volume of packed red cells

19. Structure of RBCs • Biconcave disc, providing a large surface to volume ration • Shape allows RBCs to stack, bend and flex • RBCs lack organelles • Typically degenerate in about 120 days.

20. Figure 19.2 The Anatomy of Red Blood Cells Figure 19.2

21. Hemoglobin • Molecules of hemoglobin account for 95% of the proteins in RBCs • Hemoglobin is a globular protein, formed from two pairs of polypeptide subunits • Each subunit contains a molecule of heme which reversibly binds an oxygen molecule • Damaged or dead RBCs are recycled by phagocytes

22. Figure 19.3 The Structure of Hemoglobin Figure 19.3

23. Figure 19.4 “Sickling” in Red Blood Cells Figure 19.4

24. RBC life span and circulation • Replaced at a rate of approximately 3 million new blood cells entering the circulation per second. • Replaced before they hemolyze • Components of hemoglobin individually recycled • Heme stripped of iron and converted to biliverdin, then bilirubin • Iron is recycled by being stored in phagocytes, or transported throughout the blood stream bound to transferrin

25. Figure 19.5 Red Blood Cell Turnover Figure 19.5

26. RBC Production • Erythropoeisis = the formation of new red blood cells • Occurs in red bone marrow • Process speeds up with in the presence of EPO (Erythropoeisis stimulating hormone) • RBCs pass through reticulocyte and erythroblast stages

27. Figure 19.6 Stages of RBC Maturation Figure 19.6

28. Blood types • Determined by the presence or absence of surface antigens (agglutinogens) • Antigens A, B and Rh (D) • Antibodies in the plasma (agglutinins) • Cross-reactions occur when antigens meet antibodies

29. Figure 19.8 Blood Typing and Cross-Reactions Figure 19.8

30. Figure 19.9 Blood Type Testing Figure 19.9

31. Figure 19.10 Rh Factors and Pregnancy Figure 19.10

32. SECTION 19-5The White Blood Cells

33. Leukocytes • Have nuclei and other organelles • Defend the body against pathogens • Remove toxins, wastes, and abnormal or damaged cells • Are capable of amoeboid movement (margination) and positive chemotaxis • Some are capable of phagocytosis

34. Types of WBC • Granular leukocytes • Neutrophils – 50 to 70 % total WBC population • Eosinophils – phagocytes attracted to foreign compounds that have reacted with antibodies • Basophils – migrate to damaged tissue and release histamine and heparin

35. Types of WBC • Agranular leukocytes • Monocytes - become macrophage • Lymphocytes – includes T cells, B cells, and NK cells

36. Figure 19.11 White Blood Cells Figure 19.11

37. Differential count • Indicates a number of disorders • Leukemia = inordinate number of leukocytes

38. WBC Production • Granulocytes and monocytes are produced by bone marrow stem cells • Divide to create progenitor cells • Stem cells may originate in bone marrow and migrate to peripheral tissues • Several colony stimulating factors are involved in regulation and control of production

39. Figure 19.12 The Origins and Differentiation of Formed Elements Animation: The origins and differentiation of blood cells PLAY Figure 19.12

40. SECTION 19-6Platelets

41. Platelets • Flattened discs • Circulate for 9-12 days before being removed by phagocytes

42. Platelet functions • Transporting chemicals important to clotting • Forming temporary patch in walls of damaged blood vessels • Contracting after a clot has formed

43. Platelet production (thrombocytopoiesis) • Megakaryocytes release platelets into circulating blood • Rate of platelet formation is stimulated by thrombopoietin, thrombocyte-stimulating factor, interleukin-6, and Multi-CSF

44. SECTION 19-7Hemostasis

45. Hemostasis • Prevents the loss of blood through vessel walls • Three phases – • Vascular phase • Platelet phase • Coagulation phase

46. Hemostasis • Vascular phase • Local blood vessel constriction (vascular spasm) • Platelet phase • Platelets are activated, aggregate at the site, adhere to the damaged surfaces

47. Figure 19.13 The Vascular and Platelet Phases of Hemostasis Figure 19.13

48. Coagulation phase • Factors released by platelets and endothelial cells interact with clotting factors to form a clot • Extrinsic pathway • Intrinsic pathway • Common pathway • Suspended fibrinogen is converted to large insoluble fibrin fibers

49. Figure 19.14 The Coagulation Phase of Hemostasis Figure 19.14a

50. Figure 19.14 The Coagulation Phase of Hemostasis Figure 19.14b