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Blood

Blood. Blood can actually be considered one of your body’s tissues . Formed elements all the blood cells red blood cells (RBCs) (erythrocytes) transport O 2 white blood cells (WBCs) (leukocytes) immune response and the platelets membrane sacs that help seal broken blood vessels Plasma

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Blood

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  1. Blood • Blood can actually be considered one of your body’s tissues. • Formed elements • all the blood cells • red blood cells (RBCs) (erythrocytes) • transport O2 • white blood cells (WBCs) (leukocytes) • immune response • and the platelets • membrane sacs that help seal broken blood vessels • Plasma • proteins used for blood clotting and osmotic pressure • Serum • nutrients (glc, aas, fats) • waste (mostly urea) • dissolved gases (O2, CO2, N2) • electrolytes (Na+, K+, Cl-)

  2. Blood

  3. Blood - hemopoiesis • production of blood cells • erythropoiesis -RBCs • kidneys produce erthropoietinwhen O2 levels drop • new RBCs produced inred bone marrow • negative feedback loop • production of blood cells • leukopoiesis -WBCs • triggered by infections or other attacks on the body

  4. Blood - hemopoiesis • production of blood cells • erythropoiesis -RBCs • kidneys produce erthropoietinwhen O2 levels drop • new RBCs produced inred bone marrow • negative feedback loop • production of blood cells • leukopoiesis -WBCs • triggered by infections or other attacks on the body • production of platelets • thrombopoiesis • megakarocytes • bone marrow • lungs • pinches off pieces of cytoplasm

  5. Blood - erythrocytes • Red blood cells transport O2 (and some CO2) • hemoglobin • 4 protein chains (globins) • 2 alpha chains • 2 beta chains • 4 heme groups • site where O2 molecules bind

  6. Blood - erythrocyte disorders • Polycythemia • too many red blood cells • increase blood volume • increase blood viscosity • increase blood pressure • heart over worked • can lead to embolism, stroke, heart failure • Anemia • too few blood cells carrying O2 • hemorrhagic anemia - excessive blood loss • hemolytic anemia - destruction of RBCs or too little erythropoiesis • sickle-cell anemia and thalassemia • both caused by abnormal hemoglobin

  7. Blood Types • All cells have membrane proteins that label the cell as “friend” or “foe” to the immune system • antigens • allow your immune system can differentiate your body cells from foreign or infected cells • Antigens on RBCs called agglutinogens • react with antibodies in blood called agglutinins • mismatched transfusions cause agglutination (transfusion reaction) • agglutinins bind toagglutinogens and linkRBCs together • cause RBCs toform “clumps” (agglutination)

  8. Blood Types • ABO blood groups • type A and type B agglutinogens (antigens) • just A type agglutinogens - type A blood • just B type agglutinogens - type B blood • both agglutinogens - type AB blood • no agglutinogens - type O blood • transfusion rxns can occur because you also have agglutinins (antibodies) • type A blood - antiB agglutinins • type B blood - antiA agglutinins • type AB blood - no agglutinins • type O blood - both agglutinins

  9. Blood Types • ABO blood groups • type AB blood • no agglutinins - sometimes called universal recipient • what about agglutinins in donor’s blood? • type O blood - both agglutinins • no agglutinogens - universal donor? • But has both types of agglutinins

  10. Blood Types • Rh group • Rh+ have the Rh agglutinogen • Rh- do not have Rh agglutinogen • will produce antiRh agglutinin if exposed to Rh+ blood

  11. Blood Types - hemolytic disease of the newborn (HDN) • Rh- Mom exposed to Rh+ blood of newborn at birth • no problem during first pregnancy

  12. Blood Types - hemolytic disease of the newborn (HDN) • Mom produces antiRh agglutinins

  13. Blood Types - hemolytic disease of the newborn (HDN) • Mom’s antiRh agglutinins attack Rh+ RBCs of fetus in next pregnancy • Can be prevented by treating with RhoGAM

  14. Hemostasis • The stoppage of bleeding (3 ways) • 1) Vascular Spasm • constriction of the injured blood vessel via: • pain receptors • smooth muscle damage • serotonin (released from platelets) • 2) Platelet plug formation • platelets react with collagen • adhere to inner surface of blood vessel • contract and draw the vessel walls together • release chemicals (degranulation) • serotonin (vasoconstrictor) • ADP (platelet aggregation) • thromboxane A2 (both of the above)

  15. Hemostasis 1 2 3 • The stoppage of bleeding (3 ways) • 1) Vascular Spasm • 2) Platelet plug formation • 3) Coagulation • the formation of fibrin • two pathways • intrinsic mechanism • extrinsic mechanism

  16. Hemostasis - coagulation pathways • Intrinsic mechanism • platelet degranulation releases fact. XII • triggers a cascade of rxns • fact. X activated • becomes prothrombin activator • converts prothrombin to thrombin • converts fibrinogen to fibrin • becomes fibrin polymer

  17. Hemostasis - coagulation pathways • Extrinsic mechanism • damaged tissues release thromboplastin • fact. VII activated • results in fact. X activation • becomes prothrombin activator • converts prothrombin to thrombin • converts fibrinogen to fibrin • becomes fibrin polymer

  18. Hemostasis - coagulation pathways 3 • Fibrin formation • intrinsic mech. - 3-6 min. • extrinsic mech. - ~15 sec. • Clot retraction (30 minutes) • Healing stimulated byplatelet-derived growth factor(PDGF)

  19. Hemostasis - coagulation pathways 3 • Classical hemophilia • lack of fact. VIII • hemophilia B • lack of fact. IX • clotting fact. can be produced by transgenic bacteria

  20. Circulatory System Tunica intima -mostly endothelium Tunica media -mostly smooth muscle lumen Tunica externa -mostly connective tissue • Basic structure of arteries and veins

  21. The structure of blood vessels • Blood flows from heart • into arteries • conducting • large • very elastic • distributing • feed specific organs • very muscular • resistance • arterioles • deliver blood to capillary bed • metarterioles • control blood flow within capillary bed

  22. The structure of blood vessels • capillary bed • very thin walled - just tunica intima • site of exchange between blood and body cells • nutrients, O2 CO2 , wastes

  23. The structure of blood vessels • veins • deliver blood back to heart • metavenules • venules • veins • much less smooth muscle than arteries • more fragile than arteries • varicose veins are just veins that have broken open and leak blood • contain valves to prevent blood flowing backwards

  24. Precapillary sphincters • capillary bed • very thin walled - just tunica intima • site of exchange between blood and body cells • nutrients, O2 CO2 , wastes • Blood flows from arteriole • to metarteriole • precapillary sphincters open or closeand determine if blood flows into capillary bed, • or is shunted straight thru thoroughfare channel (metavenule). • constantly adjusted (homeostasis again) - depends on activity of the body

  25. Blood Pressure • BP is not constant throughout circulatory system • when heart contracts (systole)BP goes up • systolic pressure • when heart relaxes (diastole) BP goes down • diastolic pressure • as blood flows further from the heart • BP also decreases • By the time blood reaches the veins, hardly any pressure is provided by the heart • So where does pressure come from that moves blood out of your legs and toward your heart??

  26. Skeletal Muscle Pump • Veins often run in the middle of skeletal muscle • as muscles contract, veins get squeezed • blood is pushed through vein • venous valves - prevent blood from flowing backward • blood is squeezed toward heart • What happens if you stand motionless for 60 minutes or so?

  27. The Circulatory system • Your body can control blood flow to diff. areas by changing peripheral resistance. • Regulation of peripheral resistance • Local control • accumulation of metabolic by products • CO2, H+, lactic acid (+ others) • trigger vasodilation (decrease peripheral resistance) • increased blood flow carries by products away • blood vessels constrict back to normal size • homeostasis

  28. The Circulatory system • Your body can control blood flow to diff. areas by changing peripheral resistance. • Regulation of peripheral resistance • Local control • Neural control • baroreflex • negative feedback

  29. The Circulatory system • Your body can control blood flow to diff. areas by changing peripheral resistance. • Regulation of peripheral resistance • Local control • Neural control • baroreflex • chemoreflex Decreased CO2 levels chemoreceptors fire fewer APs

  30. The Circulatory system • Your body can control blood flow to diff. areas by changing peripheral resistance. • Remember autonomic nervous system? • sympathetic division • fight and flight • diverts blood flow to prepare for stressful activity • parasympathetic division • rest and digest • diverts blood flow to GI tract

  31. The Circulatory system • So the circulatory system transports nutrients and wastes to and from the cells… • How do things move between the blood in the capillaries and the cells outside? • Three routes of capillary exchange • diffusion • most important • transcytosis • least important • filtration and reabsorption

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