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Chapter 19

Chapter 19. The Circulatory System I Blood. Cardiovascular System. The cardiovascular system includes: Blood The Heart Blood Vessels Large and small arteries and arterioles Large and small veins and venules Capillaries. Blood.

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Chapter 19

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  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 < 1% * = packed cell volume

  8. Erythrocytes (RBC’s) • Cell Structure: biconcave disc 7 μm diameter X 2 μm thick. -anucleated cells (no nucleus or other cellular organelles) • Production:erythropoiesis is stimulated by erythropoietin hormone from kidneys. -From infancy on, all rbc’s are produced in red bone marrow. They are produced from pluripotent stem cells (PPSC). • Contain 4 hemoglobin molecules/rbc; • Life span of a rbc ~ 100- 120 days

  9. Erythrocytes (RBC’s)

  10. Hemoglobin • Erythrocytes contains 4 hemoglobin molecules • Hemoglobin is a complex molecular structure of two chains: α chain is 141 amino acids; β chain is 146 amino acids. • Heme groups is bound to each chain and contains ferrrous iron (Fe+2). • Iron is where O2 binds to each Hgb molecule binds ~ 250 million molecules O2 X 4 = 1 billion molecules O2 /rbc.

  11. Hemoglobin molecular structure • Star shapes are Heme (Fe+2) molecules • Dark blue chain is β, light blue is α

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

  13. Hematopoiesis

  14. Leukocytes (WBC’s) • Cell Structure: 4,800 – 11,000/cm -Spherical cells containing a nucleus and other organelles. The nucleus of each cell type varies considerably in leukocytes and is quite conspicuous and 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. • Number ranking: NLMEB

  15. WBC’s

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

  17. Neutorphils Nucleus looks like sausage links – multilobed - account for 50% of wbcs- -3,000 to 7,000/cc -Life span- 6 hrs – few days - phagocytize bacteria

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

  19. 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

  20. 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.

  21. Lymphocytes • Round nucleus fills most of cytoplasm • Account for 25-33 % of wbc • 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

  22. 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

  23. Thrombocytes (platelets) • Cellular fragments very small under microscope. • ~ 250,000 platelets/ cc • 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.

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

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