Blood - PowerPoint PPT Presentation

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Blood

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  1. Blood

  2. Blood is a liquid connective tissue that transports various substances to body cells & helps to maintain homeostasis. • Nutrients from digestive tract to body cells • Oxygen from lungs to body cells • Wastes from cells to respiratory and excretory systems • Hormones to target tissues • Body temperature control – distributes heat

  3. Blood/Blood Cells • Volume • Varies with body size – usually between 4-6 liters • Solid portion – RBS, WBC, & platelets – Fig. 11-1 • Liquid portion – plasma (55% of blood volume)

  4. RBC’s – Erythrocytes - Fig. 11-2 • Characteristics • Biconcave disks; shape provides increased SA & places cell membrane close to internal parts • Contain hemoglobin – oxygen carrying protein • Mature RBC’s lack nucleus, but contain enzymes needed for energy releasing processes • Approx. 4-6 million/mm3

  5. RBC’s (cont.) • Destruction of RBC’s (last about 120 days) • Fragile & as they age they are damaged while moving through capillaries • Damaged cells are phagocytized by macrophages in the liver & spleen • Hb molecules are decomposed & the Fe they contain is conserved

  6. Macrophage engulfing two RBC’s

  7. RBC’s (cont.) • RBC production and its control (hematopoiesis) • During fetal development RBC’s are formed in yolk sac, liver & spleen; later produced by red bone marrow • Number remains relatively stable • Rate of RBC production is controlled by a negative feedback mechanism • Kidney & liver tissues experience oxygen deficiency • Tissues release erythropoietin • Erythropoietin travels to red bone marrow stimulating an increase in RBC production • As RBC numbers increase the oxygen carrying capacity of the blood rises • Oxygen concentration in kidney & liver increase and the release of erythropoietin decreases

  8. WBC’s leukocytes – Table 11-1, Fig. 11-4 – Function to control disease conditions • Types of WBC’s • Granulocytes – granules present in cytoplasm; include neutrophiles (phagocytize), eosinophi9ls, (defense against parasites), & basophils (inflammatory response) • Agranulocytes – monocytes & lymphocytes (humoral and cellular immune response) • Approx. 5,000 – 10,000/mm3; however the number of WBC’s may change as a result of infections, emotional disturbances or excessive loss of body fluids

  9. Functions of WBC’s • WBC’s may be stimulated by the presence of chemicals (histamine) released by damaged cells & many move toward these chemicals • http://www.youtube.com/watch?v=y3bOgdvV-_M (body’s response to an allergen) • Neutrophils & monocytesphagocytize foreign particles • http://www.youtube.com/watch?v=7VQU28itVVw&feature=related (phagocytosis – fig. 11-5)

  10. Functions of WBC’s • Eosinophils kill parasites & help control inflammation & allergic reactions • Basophils release heparine – inhibits blood clotting • Lymphocytes produce antibodies that act against specific foreign substances • http://www.dnatube.com/video/194/Specific-Adaptive-immunity-humoral-and-cell-mediated (immune response)

  11. Platelets - thrombocytes • Fragments of giant cells that become detached & enter circulation • Help close breaks in blood vessels, Fig. 11-6 • Approx. 130,000 – 360,000/mm3 • Hemostasis – stoppage of bleeding • http://www.youtube.com/watch?v=--bZUeb83uU&feature=related (blood clotting) • Be familiar with the steps of blood clotting shown in the above link

  12. Blood Clot

  13. Blood Plasma • Liquid port of the blood that is composed of H2O and a mixture of organic & inorganic substances. It transports nutrients & gases, regulates fluid and electrolyte balance and helps maintain a stable pH.

  14. Blood Types – blood can be typed on the basis of antigens displayed on the cell membranes of RBC’s • Antigens & antibodies Fig. 11-7 • RBC membranes may contain antigens (agglutinogens) and blood plasma may contain antibodies (agglutinins) • Blood typing involves identifying the antigens present on the red cell membranes

  15. ABO Blood Groups • Type A blood • Type A antigen; type B antibody • Type B blood • Type B antigen; type A antibody • Type AB blood • Type A & B antigens; no antibodies • Type O blood • No antigens; A & B antibodies

  16. ABO Blood Groups • Adverse transfusion reactions are avoided by preventing the mixing of blood that contain the antigen with plasma that contains the corresponding antibody • Adverse reactions involve agglutination (clumping) of the RBC’s • For example – if RBC’s with antigen A are added to blood containing antibody A….. The antibodies react with the antigens of the RBC’s and cause them to clump together

  17. Agglutination

  18. Rh Blood Group • Rh antigens are present in the RBC membranes of Rh+ blood; they are absent in Rh- blood • No antibodies are present in RH+ blood (do not develop spontaneously) • Mixing Rh+ RBC’s with plasma that contains anti-Rh antibodies results in agglutination of the + cells

  19. Erythroblastosisfetalis – Fig. 11-8 • Rh- woman becomes pregnant with her first Rh+ child • Pregnancy is uneventful, but at time of birth some Rh+ cells enter maternal circulation through damaged placental tissues • Maternal tissues produce anti-Rh antibodies • Second Rh+ child is conceived • Anti-Rh antibodies from the maternal circulation pass through the placental membranes & enter the fetal blood • Fetal blood agglutinates because of reaction with the anti-Rh antibodies