Chapter 19

1. Chapter 19 The Circulatory System I Blood

2. Cardiovascular System • The cardiovascular system includes: • Blood • The Heart • Blood Vessels • Large and small arteries and arterioles • Large and small veins and venules • Capillaries

3. Blood • A liquid connective tissue made up of plasma and formed elements. • BLOOD COMPOSITION: • Serum: the liquid portion of blood after it has clotted ( fibrinogen has clotted). • Plasma: liquid portion of blood • Water – 92% by weight • Proteins – 6-9 gm/dl; most abundant plasma solute • Formed elements (rbc, wbc and platelets)

4. Blood fractions

5. Blood

6. Blood Proteins • Albumin is the major contributor to plasma viscosity and osmolarity. Albumin- smallest and most abundant protein; serves to transport plasma solutes and buffer the pH of blood plasma. • Fibrinogen- soluble precursor of fibrin, a sticky protein that forms framework for clotting. • Globulins-3 classes: alpha (α), beta (β) and gamma (γ) (smallest to largest) in molecular weight.

7. Formed Elements • Red blood cells (rbc) = erythrocytes ~45-50% pcv* • White blood cells (wbc) = leukocytes ~ < 1% pcv* • Granulocytes- neutrophils, eosinophils and basophils • Agranulocytes- lymphocytes and monocytes • Thrombocytes = platelets (part of buffy coat) * = packed cell volume

8. Erythrocytes (RBC’s) • 4.2 – 6.2 million per mm3 • Cell Structure: biconcave disc 7.5 μm diameter, X 2 μm thick. • anucleated cells (no nucleus or other cellular organelles) • Production:erythropoiesis is stimulated by erythropoietin, a hormone from kidneys. -From infancy on, all rbc’s are produced in red bone marrow. They are produced from pluripotent stem cells (PPSC). • Contain 280 million hemoglobin molecules/rbc; • Life span of a rbc ~ 100- 120 days

9. Erythrocytes (RBC’s)

10. Hemoglobin • Hemoglobin (Hgb) is a complex molecular struc-ture of four polypeptide chains: 2 α chains and 2 β chains. • Each α chain contains 141 amino acids; β chain contains 146 amino acids. • One heme group is bound to each chain and contains ferrous iron (Fe+2). • Oxygen binds to Fe+2. Each Hgb molecule binds four oxygen atoms. Therefore each RBC can transport about 4 x 280 million oxygen atoms

11. Hemoglobin molecular structure • Star shapes are heme groups containing Fe+2 • Dark blue chain is β, light blue is α

12. Blood types • Most familiar blood types are ABO groups and Rh group. • Blood type antigens are carried on red blood cell membranes. • Blood types A,B,O and AB involve the ABO group • O is “universal donor”; AB is “universal recipient”. • Rh factor may be present (+) or absent (-) and immune reactions can result if not properly matched.

13. Hematopoiesis

14. Leukocytes (WBC’s) • Cell Structure: 4,800 – 11,000/mm3 -Spherical cells containing a nucleus and other organelles. The nucleus of each cell type varies considerably in leukocytes and is quite conspicuous, thus helps in identifying each cell type. • Production: -stimulated by two cytokines: (interleukin and colony stimulating factor [CSF]). -All wbc’s are produced from PPSC by a process called leucopoiesis. WBC’s are produced in red bone marrow and may remain there until needed in the body or they may migrate to other organs for further differentiation. • Percentage ranking: NLMEB

15. Differential Leukocyte Count • Smear a drop of blood over a slide • Stain the blood smear with Wright’s stain - gentian violet stains nuclei violet - eosin stains proteins pink • Count 100 leukocytes, tallying each type neutrophils: 60 – 70% of total count lymphocytes: 20 – 25 % monocytes: 3 – 8 % eosinophils: 2 – 4 % basophils: 0.5 – 1 % :

16. WBC’s

17. Granulocytes • Leukocytes that contain granules in their cytoplasm: • Neutrophils – most plentiful in blood (60 – 70 %) • Eosinophils– 1 – 4% of wbc’s • Basophils- least plentiful of all wbc’s ~ 0.5% wbc’s

18. Neutrophils Nucleus looks like sausage links – multilobed - about 60% of wbcs: 3,000 to 7,000/mm3 -Life span: 6 hrs – few days - phagocytize bacteria

20. Eosinophils • Bilobed nucleus • Account for 1-4% of wbc • Red staining granules • Life span- 8 – 12 days • Kill parasitic worms, active in allergies

21. Basophils • Bilobed nucleus “U” or “S” • Account for < 0.5% wbc • Dark bluish-purple staining granules • Life span- hrs. - days • Contain histamine, and inflamatory substances

22. Agranulocytes • Conspicuous granules are lacking in the cytoplasm. • Composed of: Lymphocytes and Monocytes. • Lymphocytes are most important in immune system in lymph nodes, Peyers patches, and spleen.

23. Lymphocytes • Round nucleus fills most of cytoplasm • Account for 25-33 % of wbc’s • Similar size to neutrophils • Life span- hrs. to years • Two types: “B” and “T” • B cells mature in red bone marrow • T cells start in red marrow and mature in Thymus gland

24. Monocytes • Largest wbc’s in circulation • Large “U: shaped or kidney shaped nucleus • Account for 4-8% of wbcs • Life span- months • Active in clotting to plug holes until clot can form. • Become macrophages after release from red bone marrow into circulation • Macrophages are major phagocytes in body

25. Thrombocytes (platelets) • Cellular fragments very small under microscope. • ~ 250,000 platelets/ mm3 • Contain serotonin, Ca++, enzymes and platelet growth factor. • Stick together to form plugs and stop bleeding (hemostasis). Picture is of a megakaryocyte from which platelets are produced.

26. Blood clot of fibrin and platelets and other blood cells