section 1, chapter 14: blood


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red blood cells and white blood cells

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section 1, chapter 14: blood

  1. 1. Chapter 14, Section 1 of 2. Blood Functions of Blood: 1. Transports gasses, (O2 and CO2) 2. Transport nutrients, wastes, electrolytes, and hormones 3. Distributes heat throughout the body 4. Contains buffers 5. Immunity
  2. 2. Introduction Characteristics of Blood: Blood is a connective tissue 1. Cells are called= formed elements • Red Blood Cells • White Blood Cells • Platelets 2. Liquid Matrix = plasma Centrifuged Blood: 1. Plasma, 55% 2. Buffy Coat, <1% • Proteins and WBCs 3. Red Blood Cells, 45% • Hematocrit = packed RBCs
  3. 3. Hematopoiesis Hematopoiesis is the formation of new blood cells. • Occurs within red bone marrow • Blood stem cells are called, hemocytoblasts ( or hematopoietic stem cells) • Hemocytoblasts can give rise to additional blood stem cells • Can differentiate into any of the blood cells • The fate of hemocytoblast depends on hematopoietic growth factors Example: Erythropoietin (EPO = growth factor) Hemocytoblast erythroblast reticulocyte erythrocyte (RBC)
  4. 4. Erythrocytes: red blood cells (corpuscles) Characteristics of erythrocytes 1. Biconcave cells 2. anucleated (nucleus dislodged during formation) 3. Average diameter = 7.5µm 4. 1/3 volume is hemoglobin • Oxyhemoglobin – bright red • Deoxyhemoglobin – dark brick red Red Blood Cell Counts RBC counts is the number of RBCs in a cubic millimeter or microliter of blood 1. Male 2. Female 3. Child 4.6 - 6.2 million cells per µL 4.2 - 5.4 million cells per µL 4.5 - 5.1 million cells per µL
  5. 5. Erythropoiesis: RBC production Sites of Erythropoiesis Adult – Erythropoiesis occurs primarily in red bone marrow, which is found within • flat bones (sternum, pelvis, ribs, skull) • Proximal end of long bones (femur, humerus) Child • Erythropoiesis occurs within the yolk sac, liver, and spleen Example of erythropoiesi: Erythropoietin (EPO) In red bone marrow circulation
  6. 6. Erythrocytes: feedback loop Erythopoiesis is stimulated by low blood oxygen. • Decreased blood O2 may cause the kidneys and the liver (to a lesser extent) to release erythropoietin (EPO) • EPO stimulates RBC production • This is a negative feedback mechanism • Within a few days many new blood cells appear in the circulating blood Dietary Factors of Erythropoiesis • Iron – required for hemoglobin production • Vitamin B12 & Folic Acid – required for DNA synthesis (and thus, cell production)
  7. 7. Lifespan of Red Blood Cells Red blood cells survive about 120 days in circulation. • With age, RBCs become fragile and easily rupture. • Old RBCs are removed by the liver and spleen • Hemoglobin is liberated and recycled in new RBCs
  8. 8. Hemoglobin breakdown Hemoglobin Heme + Globin Amino acids • recycled by body Biliverdin + Iron (Fe2+) • Reused by liver in synthesis of new hemoglobin Bilirubin • Excreted as bile pigment Jaundice: yellowish staining of skin caused by the accumulation of bile pigments. Jaundice may indicate increased RBC destruction, destruction of liver tissue, or blockage of the biliary tract.
  9. 9. Red Blood Cell Disorders Erythrocytosis (polycythemia) is an excess number of RBCs in the blood. • Causes include 1. Genetic mutations 2. Poor blood oxygen levels or delivery 3. tumor Polycythemia. The surplus of RBCs causes the blood to be more viscous and it slows its flow through the body. This increases the likelihood of clot formation. Anemia • Low oxygen capacity of blood, several types 1. Iron deficiency – body cannot form hemoglobin 2. Hemolytic – excess RBC destruction 3. Sickle cell – sickle-shaped RBCs 4. Aplastic – inability to produce RBCs Sickle cell anemia. RBCs take on a thin sickle shape when deoxygenated. The sickle cells sludge in capillaries, further reducing blood flow and oxygen levels
  10. 10. Leukocytes (White Blood Cells) Functions of WBCs 1. Protect against infection 2. Remove worn out cells & debris 3. immunity Colony Stimulating Factors and Interleukins are growth factors that promote the development of white blood cells. There are five types of white blood cells within 2 categories Granulocytes • Visible lysosomes “granules” in cytoplasm 1. Neutrophil 2. Eosinophil 3. Basophil Agranulocytes • No visible granules in cytoplasm 1. Monocyte 2. Lymphocyte
  11. 11. Neutrophils Overview: 1. Neutrophils stain in acid-base stains 2. Constitutes 54-62% of WBCs 3. Also called polymorphonuclear leukocytes “polymorphs” 4. Contain 2-5 nuclei + fine purple granules 5. 12 hour lifespan Functions 1. Phagocytosis • Kill bacteria, protozoa, fungi, parasites • Remove dead cells, debris, and foreign particulate 2. First to arrive at the site of infection • Fast moving cells neutrophil, 1000x
  12. 12. Eosinophils Overview: 1. Constitute 1-3% of all WBCs 2. Bi-lobed nucleus 3. Granules stain bright red in acid stain Functions 1. Defend against parasitic worms (tapeworm, hookworm, fluke worm, ect) 2. mediates allergic reaction and asthma attacks eosinophil, 1000x
  13. 13. Basophils Overview: 1. Constitutes <1% of WBCs 2. Deep blue granules stain in basic dye 3. Bilobed nucleus is usually obscured by the darkened granules Functions 1. Secretes histamines • Histamines promote inflammation 2. Secretes heparin • Heparin is an anticoagulant “prevents clotting” basophil, 1000x
  14. 14. Monocytes Overview: 1. Constitutes 3-9% of WBC 2. Largest of all WBCs 3. Large kidney-shaped nucleus 4. May live for several weeks up to a month Functions 1. Leave the blood to become macrophages 2. Phagocytize bacteria, dead cells and other debris platelet monocyte, 1000x
  15. 15. Lymphocytes Overview: 1. Constitutes 23-33% of all WBCs 2. Formed in red bone marrow and in lymphatic tissues 3. Large spherical nucleus with a thin sliver of cytoplasm 4. May live for many months to several years 5. Includes T-cells & B-cells Functions 1. Lymphocytes provide immunity • T-cells directly attack microorganisms and tumor cells • B-cells produce antibodies lymphocyte, 1000x
  16. 16. Functions of white blood cells 1. Leukocytes (primarily neutrophils & monocytes) are motile • Exhibit amoeboid movement • Neutrophils & Monocytes are the most mobile of WBCs 2. Leukocytes are capable of diapedesis. • They can squeeze between the cells of a capillary wall and enter the tissue space outside the blood vessel. 3. Leukocytes exhibit chemotaxis. • They are attracted to chemicals released by damaged tissues. 4. Leukocytes contribute to the formation of pus. • Pus is the accumulation of bacteria, damaged tissue, and dead white blood cells. Figure 14.15 illustrates diapedesis of a WBC from a capillary into the surrounding connective tissue.
  17. 17. Activation of WBCs Figure 14.16 When bacteria invade the tissues, leukocytes migrate into the region and destroy the microbes by phagocytosis.
  18. 18. White Blood Cell Counts A typical white blood count contains 4,500-10,000 WBCs per µL (mm3) Leukopenia is a low WBC count (below 4,500 cells/µL) • Often associated with viral infections (influenza, chicken pox, measles, AIDS) Leukocytosis is a high WBC count (above 10,000 cells/µL) • Acute infection, exercise, emotional distress DIFF (differential WBC count) • Measures the percentages specific types of WBC Table 14.4 illnesses associated with various DIFF counts
  19. 19. Thrombocytes (platelets) TPO Overview 1. Platelets are cell fragments released from Megakaryocytes within red bone marrow 2. Approximately 150,000 - 450,000 platelets per µL (mm3) of blood. 3. Thrombopoietin (TPO) = growth factor that promotes formation of platelets. 4. Functions include blood coagulation and blood vessel repair Figure 14.4. Development of platelets from hemocytoblasts. Exposure to TPO promotes the formation of megakaryocytes, which release thrombocytes from their plasma membrane.
  20. 20. Overview of Blood Cells End of Section 1 of 2.