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1. 17 Blood Modified by: Olga E. Vazquez

2. Cardiovascular System • Cardio = heart • Vascular = blood vessels • Consists of three interrelated components: • Blood • Heart • Blood vessels

3. Basics of Blood • Blood is Fluid Connective Tissue • Blood components • Plasma (matrix) - nonliving • Formed elements (cells) - living • Hematopoiesis – formation of blood cells

4. Blood: An Overview • Blood and the interstitial fluid (IF) are 2 fluids that provide O2 and nutrients and remove CO2 and other waste. • How do they do it? • IF bathes body cells • O2 and nutrients diffuse from blood → IF → cells • Waste and CO2 diffuse cell → IF → blood

5. Plasma • Makes up 55% of blood • 90% water;plasma also contains : • Proteins such as antibodies • Gases • Hormones • Waste

6. Formed Elements • These cells have unusual features. • Two of the three are not even true cells. Why? • Erythrocytes have no nuclei or organelles, and platelets are cell fragments. Only leukocytes are true cells • Most of the formed elements survive in the bloodstream for only a few days. • Most blood cells do not divide.

7. Formed Elements • RBC or erythrocytes are involved in gas transport • Carry O2 • Carry CO2

8. Structural Characteristics of RBCs • Major function of RBC is to transport hemoglobin. • Erythrocytes are over 97% hemoglobin.

9. Destruction of Erythrocytes • RBCs are anucleate • Limitations due to lack of nucleus: • Red blood cells are unable to synthesize new proteins, to grow, or to divide. • Erythrocytes become “old” & hemoglobin begins to degenerate.

10. Destruction of Erythrocytes • Red blood cells have a useful life span of 100 to 120 days, after which they become trapped in the spleen. • In the red pulp of the spleen, RBC rupture when they try to squeeze through because of their fragile old membrane. • For this reason, the spleen is sometimes called the “red blood cell graveyard”.

11. Formed Elements • WBC (white blood cells) or leukocytes have many specialized functions. • What is the purpose of WBCs ?

12. Formed Elements • Leukocytes: • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Lymphocytes • Monocytes

13. Formed Elements • Platelets • Cell fragments • Encourage clot formation

14. Formed Elements Formation • Hematopoiesis (hemato = blood, poiesis = to make) • Process in which formed elements of the blood develop • Erythropoiesis • Leukopoiesis • Before birth it occurs • Yolk sac • Later in the liver, spleen, thymus and lymph nodes • Last 3 months of gestation in the red bone marrow

15. Hematopoiesis • During childhood (up to 5 years) occurs in the epiphysis of almost all long bones. • In adults it occurs also in flat and irregular bones such as the skull, sternum, hip bone, ribs, and vertebra. • Formed element production in adults occurs in the humerus and femur.

16. ABO Markers

17. Leukocytes • Leuko = • They are also known as white blood cells • Only formed elements that are complete cells with a nucleus and usual organelles.

18. Leukocytes • What do you know about these cells?

19. Categories of Leukocytes • Leukocytes are grouped into two major categories: • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Lymphocytes • Monocytes

20. Granulocytes • All are roughly spherical in shape • Stored in bone marrow until needed • They are larger than erythrocytes

21. Neutrophils • Respond most quickly to tissue destruction by bacteria or fungus • Active in phagocytosis

22. Neutrophils • Neutrophils are our body’s bacteria slayers • First one at “war zone”. • Can phagocytize 5-20 bacteria before it dies.

23. Eosinophils •  Parasitic worms (most important role) • Release enzymes onto the parasite’s surface, digesting it away

24. Basophils • Similar in function to mast cells • Bind to IgE, which causes cells to release histamine • Release of histamine intensifies inflammatory reactions

25. Granulocytes • All granulocytes are phagocytic but neutrophils are the most phagocytic of them all.

26. Agranulocytes • Include lymphocytes and monocytes • Both produced in red bone marrow but lymphocytes can also be produced in lymphatic organs such as lymph nodes and spleen. • Major soldiers with a life span of 100-300 days

27. B Lymphocytes • B cells • Attack bacteria, viruses and toxins • Plasma cells → antibodies (Ig = immunoglobulin) • Memory cells • Keep a “record” of pathogens

28. T Lymphocytes • T cells • Acting directly against virus-infected cells and tumor cells • CD 4 • T helper cells • CD 8 • T cytotoxic cells

29. NKC • Natural Killer Cells • Wide variety of microbes and tumor/cancer cells

30. Movement of Lymphocytes • Recirculate (another difference from granulocytes) • blood → interstitial space → lymphatic fluid → blood • Show ability to deformate 

31. Monocytes • Take longer to get there but arrive in larger numbers • Migrate from blood into tissues where they enlarge and become macrophages (which are phagocytic) • Destroy more microbes • 100 bacteria because they extrude toxins

32. Macrophages • Most powerful phagocyte • Engulf larger and 5 times as many particles as neutrophils • They can phagocytize whole RBC, malarial parasites and dead neutrophils • They are very important in starting immune responses • They can be called different names when they stay in different tissues.

33. Macrophages and MHC • MHC – major histocompatibility complex (self antigen) • Glycoproteins that protrudes from plasma membrane into ECF • Cell identity markers unique for each person, what about identical twins?

34. Platelets • Platelets are essential for the clotting process that occurs in plasma when blood vessels are ruptured or their lining is injured. • By sticking to the damaged site, platelets form a temporary plug that helps seal the break.

35. Platelet Plug Formation • Platelet Aggregation • A positive feedback cycle that activates and attracts greater and greater numbers of platelets to the area begins and, within one minute, a platelet plug is built up, which further reduces blood loss

36. THE END