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Cardiovascular System: Blood

Cardiovascular System: Blood. General Properties of Blood. Volume in adult body Female = 4 -5 liters Male = 5 – 6 liters pH = 7.35 to 7.45 Temp = 38 o C 100.4 o F. Hematocrit. Hematocrit = percent volume of whole blood occupied by RBC. Erythrocytes or Red Blood Cells

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Cardiovascular System: Blood

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  1. Cardiovascular System: Blood

  2. General Properties of Blood • Volume in adult body • Female = 4 -5 liters • Male = 5 – 6 liters • pH = 7.35 to 7.45 • Temp = 38 oC • 100.4 oF

  3. Hematocrit • Hematocrit • = percent volume • of whole blood • occupied by RBC p 682

  4. p 681

  5. Erythrocytes or Red Blood Cells • No nucleus • Life span = about 120 days • Average Count • Male = 5.4 million / mm3 (μL) • Female = 4.8 million / mm3 (μL) • Production called erythropoiesis • Takes about 4 days • Rate = 2 to 3 million per second ! p 687

  6. Erythrocytes on the tip of a hypodermic needle p 685

  7. Hemoglobin • Globin = one of four protein chains • Heme = one of four nonprotein parts with an Fe++ at their center that binds with O2 for transport • About 280 million hemoglobin molecules per RBC p 686

  8. What kind of feedback system? p 688

  9. Recycling Iron • On average about 26 mg of Fe+2 is used to make new hemoglobin per day • Body only requires about 1-2 mg per day from diet to replace Fe+2 lost in kidney & GI tract p 689

  10. Hemoglobin Recycling • Iron • Amino Acids from globin proteins p 689

  11. Leukocytes or White Blood Cells • 5,000 to 10,000 / mm3 (μL) • Compared to about 5 million for RBC • Granulocytes • Eosinophils • Basophils • Neutrophils • Agranulocytes • Monocytes • Lymphocytes

  12. Protection against foreign invaders in body • Neutrophils – phagocytosis • Eosinophils – phagocytosis • Basophils – release histamine & heparin • Lymphocytes – produce immune response to remove foreign antigens • Monocytes – differentiate into macrophages • (large phagocytes) p 698-9

  13. Platelets (Thrombocytes) • Not really cells, but fragments of a larger cell called a megakaryocyte • Average 250,000 / mm3 (μL) • Play a major role in hemostasis or stopping bleeding p 703

  14. Hemostasis p 704

  15. Vascular Spasm • Vascular spasm is vasoconstriction of a damaged vessel to stop or slow flow of blood for 20 to 30 minutes to • “buy time” for other mechanisms to start working p 704

  16. Platelet Plug Formation • Platelet Adhesion = platelets stick to exposed collagen • Platelet Aggregation = platelets stick to each other & build up a mass called a platelet plug • Platelet Activation = platelets develop cytoplasmic processes (pseudopods) & degranulate (exocytosis of granule contents) p 704

  17. Platelet Activation: Degranulation • Granules contain: • ADP = primary stimulus for platelet aggregation & activation • Thromboxane A2 = stimulates aggregation, degranulation, & vasoconstriction • Serotonin = stimulates vasoconstriction • Platelet derived growth factors (PDGF) = promote division of endothelia, smooth muscle & fibroblasts • Ca++ = increases local supply • = POSITIVE FEEDBACK LOOP

  18. Coagulation • Three Basic Stages: • 1) Form Prothrombin Activator • Extrinsic pathway • Intrinsic pathway • 2) Form Thrombin • 3) Form Fibrin p 704

  19. Clot Retraction • Platelets contract and pull on fibrin strands • Clot becomes denser & stronger • Pulls edges of damaged vessel together • Squeezes out serum

  20. Fibrinolysis • Plasmin activated by; • Factor XII • Plasmin • Thrombin • Tissue Plasminogen Activator (t-PA) p 708

  21. To Clot or Not to Clot • Thrombin diluted by blood • Fibrin inactivates most of thrombin at wound • Liver removes active clotting factors from blood (leaves inactive factors) • Anticoagulants; • Antithrombin from liver inactivates thrombin • Heparin from mast cells & basophils helps prevent coagulation

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