ANAPHY-LEC (BLOOD 1)

• 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

  
• 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, erythrocytes, leukocytes, thrombocytes

  
• 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


  Produces formed elements, occurs in fetus in liver, thymus, spleen, lymph nodes, and red bone marrow, after birth primarily in red bone marrow, stem cells differentiate to form different cell lines

  
• Erythrocytes


  • Red blood cells, disk-shaped with thick edges, nucleus is lost during development, live for 120 days, function is to transport O2 to tissues

  
• Hemoglobin


  Main component of erythrocytes, transports O2, each globin protein is attached to a heme molecule containing one iron atom that O2 binds to, oxyhemoglobin is hemoglobin with an O2 attached

  
• Production of Erythrocytes


  Decreased blood O2 levels cause kidneys to increase production of erythropoietin, erythropoietin stimulates red bone marrow to produce more erythrocytes, increased erythrocytes cause an increase in blood O2 levels

  
• Fate of Old Erythrocytes and Hemoglobin

  Old red blood cells are removed from blood by macrophages in spleen and liver, hemoglobin is broken down, globin is broken down into amino acids, hemoglobin's iron is recycled, heme is converted to bilirubin, bilirubin is taken up by liver and released into small intestine as part of bile

  
• 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)
• Platelets


  Minute fragments of cells, each consisting of a small amount of cytoplasm surrounded by a cell membrane, produced in the 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 that results when smooth muscle within the wall of the vessel contracts, can close small vessels completely and stop the flow of blood through them, stimulated by chemicals released by cells of the damaged blood vessel wall and by platelets
• Platelet Plug Formation


  Platelet adhesion (platelets stick to exposed collagen in damaged blood vessel wall), platelets become activated, change shape, and release chemicals, fibrinogen forms bridges between fibrinogen receptors of numerous platelets resulting in a platelet plug

  
• Blood Clotting


  Blood can be transformed 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

  Injury to a blood vessel causes inactive clotting factors to become activated due to exposed conn. tissue or release of thromboplastin, prothrombinase (clotting factor) is formed and acts upon prothrombin, prothrombin is switched to its active form thrombin, thrombin activates fibrinogen into its active form fibrin, fibrin forms a network that traps blood (clots)

  
• Anticoagulants


  Prevent clots from forming, example - heparin and antithrombin, injury causes enough clotting factors to be activated that anticoagulants can't work in that particular area of the body
• Clot Retraction and Fibrinolysis

  Clot retraction (condensing of clot, serum in plasma is squeezed out of clot, helps enhance healing), fibrinolysis (process of dissolving clot, plasminogen breaks down fibrin)

  
• Antigens


  Molecules on surface of erythrocytes
• Antibodies


  Proteins in plasma
• Blood Groups

  • ABO blood group system (type A, type B, type AB, type O)
• ABO Blood Groups

  Type A blood has type A antigens, type B blood has type B antigens, type AB blood has both types of antigens, type O blood has neither A nor B antigens, plasma from type A blood contains anti-B antibodies, plasma from type B blood contains anti-A antibodies, type AB blood plasma has neither type of antibody, type O blood plasma has both anti-A and anti-B antibodies

  
• In Caucasians in the United States, the distribution is type O, 47%; type A, 41%; type B, 9%; and type AB, 3%. Among African-Americans, the distribution is type O, 46%; type A, 27%; type B, 20%; and type AB, 7%.
• Agglutination Reaction


  Clumping of blood cells (bad)

  
• Blood Donor and Recipient According to ABO Blood Types

  O are universal donors because they have no antigens, type A can receive A and O blood, type B can receive B and O blood, type AB can receive A, B, AB blood, type O can only receive O blood

  
• Rh Blood Group


  Rh positive means you have Rh antigens, 95 to 85% of the population is Rh+, antibodies only develop if an Rh- person is exposed to Rh+ blood by transfusion or from mother to fetus
• Rh Incompatibility in Pregnancy


  If mother is Rh- and fetus is Rh+ the mother can be exposed to Rh+ blood if fetal blood leaks through placenta and mixes with mother's blood, first time this occurs mother's blood produces antibodies against antigens, any repeated mixing of blood causes a reaction

  
• Hemolytic Disease of Newborn


  Occurs when mother produces anti-Rh antibodies that cross placenta and agglutination and hemolysis of fetal erythrocytes occurs, can be fatal to fetus, prevented if mother is treated with RhoGAM which contains antibodies against Rh antigens
• Complete blood count


  Provides information such as RBC count, hemoglobin, hematocrit, and WBC count

  
• Hematocrit


  Percentage of total blood volume composed of RBC
• Hemoglobin


  Determines amount of hemoglobin, indicate anemia

  
• Prothrombin time


  Time it takes for blood to begin clotting (9 to 12 sec.)

  
• White blood cell count


  Total number of white blood cells
• White blood cell differential count

  Determines the percentage of each 5 kinds of leukocytes (neutrophils, lymphocytes, monocytes, eosinophils, basophils)

  
• Leukopenia


  Low white blood cell count, caused by radiation, chemotherapy drugs, tumors, viral infections

  
• Leukocytosis


  High white blood cell count, caused by infections and leukemia