ANAPHY LEC BLOOD(BOOK)

• Functions of Blood


  • Transport of gases, nutrients and waste products
  • Transport of processed molecules
  • Transport of regulatory molecules
  • Regulation of pH and osmosis
  • Maintenance of body temperature
  • Protection against foreign substances
  • Clot formation
• Composition of Blood 1

  • Plasma
  • Formed Elements
• Plasma


  55% of total blood, pale, yellow liquid that surrounds cells, 91% water, 7% proteins, and 2% other
• Formed Elements


  45% of total blood, cells and cell fragments
• Plasma Proteins


  • Albumin (58% of plasma proteins, helps maintain water balance)
  • Globulins (38% of plasma proteins, helps immune system)
  • Fibrinogen (4% of plasma proteins, aids in clot formation)
• Hematopoiesis


  1. Process that produces formed elements

  2. In fetus occurs in liver, thymus, spleen, lymph nodes, and red bone marrow

  3. After birth primarily in red bone marrow, some white blood cells produced in lymphatic tissues
• Stem cells/Hemocytoblasts


  Single population of cells that differentiate to give rise to different cell lines, each ending with the formation of a particular type of formed element
• Erythrocytes (Red blood cells)


  • Disk-shaped with thick edges, lose nucleus during development, live for 120 days, function is to transport O2 to tissues
• Hemoglobin


  Main component of erythrocytes, transports O2, each globin protein attached to a heme molecule containing one iron atom, O2 binds to iron
• Production of Erythrocytes


  1. Decreased blood O2 levels cause kidneys to increase production of erythropoietin

  2. Erythropoietin stimulates red bone marrow to produce more erythrocytes

  3. Increased erythrocytes cause an increase in blood O2 levels
• Figure 11.5
• Fate of Old Erythrocytes and Hemoglobin


  1. Old red blood cells removed from blood by macrophages in spleen and liver

  2. Hemoglobin broken down, globin broken down into amino acids, iron recycled, heme converted to bilirubin, bilirubin taken up by liver and released into small intestine as part of bile
• Figure 11.6
• Leukocytes (White blood cells)


  • Lack hemoglobin, larger than erythrocytes, contain a nucleus, functions are to fight infections and remove dead cells and debris by phagocytosis
• Types of Leukocytes

  • Granulocytes (neutrophils, eosinophils, basophils)
  • Agranulocytes (monocytes, lymphocytes)
• Neutrophils


  • Most common, remain in blood for 10 to 12 hours then move to tissues, phagocytes
• Eosinophils


  • Reduce inflammation, destroy parasites
• Basophils


  • Least common, release histamine and heparin
• Monocytes


  • Largest sized white blood cells, produce macrophages
• Lymphocytes


  • Involved in immune response, several different types (T cells and B cells) lead to production of antibodies
• Figure 11.8 (a-e)
• Platelets


  Minute fragments of cells, each consisting of a small amount of cytoplasm surrounded by a cell membrane, produced in red bone marrow from large cells called megakaryocytes, play an important role in preventing blood loss
• Preventing Blood Loss


  1. Vascular spasm (temporary constriction of blood vessel)

  2. Platelet plugs (can seal up small breaks in blood vessels)

  3. Blood clotting (coagulation)
• Vascular Spasm


  Immediate but temporary constriction of a blood vessel resulting from smooth muscle within the vessel wall contracting, stimulated by chemicals released by damaged blood vessel wall and platelets
• Platelet Plug Formation


  1. Platelet adhesion to exposed collagen in damaged blood vessel wall

  2. Platelets become activated, change shape, and release chemicals

  3. Fibrinogen forms bridges between fibrinogen receptors of numerous platelets, resulting in a platelet plug
• Figure 11.9
• Blood Clotting


  Transformation of blood from a liquid to a gel, clot is a network of thread-like proteins called fibrin that trap blood cells and fluid, depends on clotting factors (proteins in plasma only activated following injury, made in liver, require vitamin K)
• Steps in Clot Formation

  1. Injury to a blood vessel causes inactive clotting factors to become activated due to exposed connective tissue or release of thromboplastin

  2. Prothrombinase (clotting factor) is formed
• Platelet adhesion


  1. Platelets stick to exposed collagen in damaged blood vessel wall

  2. Platelets become activated, change shape, and release chemicals
• Platelet aggregation


  Fibrinogen forms bridges between fibrinogen receptors of numerous platelets, resulting in a platelet plug
• Clot


  Network of thread-like proteins called fibrin that trap blood cells and fluid
• Clotting factors


  • Proteins in plasma only activated following injury
  • Made in liver
  • Require vitamin K
• Clot formation


  1. Injury to blood vessel causes inactive clotting factors to become activated due to exposed connective tissue or release of thromboplastin

  2. Prothrombinase is formed and acts upon prothrombin

  3. Prothrombin is switched to its active form thrombin

  4. Thrombin activates fibrinogen into its active form fibrin

  5. Fibrin forms a network that traps blood (clots)
• Anticoagulants


  Prevent clots from forming (e.g. heparin and antithrombin)
• Clot retraction


  1. Condensing of clot

  2. Serum in plasma is squeezed out of clot

  3. Helps enhance healing
• Fibrinolysis


  1. Process of dissolving clot

  2. Plasminogen (plasma protein) breaks down clot (fibrin)
• Antigens


  Molecules on surface of erythrocytes
• Antibodies


  Proteins in plasma
• ABO blood groups


  • Type A
  • Type B
  • Type AB
  • Type O
• Type A blood


  Has type A antigens