Blood

• 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
• Characteristics of Blood


  • Type of connective tissue
  • Sticky
  • Heavier than water
  • O2 content determines color
  • Temp. slightly higher than rest of body
  • Males (5-6 L), females (4-5 L)
• Percentage of Blood Components

  • Plasma (percentage by weight): Albumins 58%, Globulins 38%, Fibrinogen 4%
  • Plasma (contents): Ions, Nutrients, Waste products, Gases, Regulatory substances
  • White blood cells: Neutrophils 60%-70%, Lymphocytes 20%-25%, Monocytes 3%-8%, Eosinophils 2%-4%, Basophils 0.5%-1%
  • Red blood cells: 4.2-6.2 million
  • Formed elements: 45%
  • Plasma: 55%, Proteins 7%, Water 91%, Other solutes 2%
  • Formed elements (number per cubic mm): Platelets 250-400 thousand, White blood cells 5-10 thousand
• 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
• Erythrocytes (Red blood cells)


  • Disk-shaped with thick edges, Nucleus is lost during development, Live for 120 days, Function: transport O2 to tissues
• Hemoglobin


  Main component of erythrocytes, Transports O2, Each globin protein is attached to a heme molecule, Each heme contains one iron atom, O2 binds to iron, Oxyhemoglobin: hemoglobin with an O2 attached
• 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
• Fate of Old Erythrocytes and Hemoglobin

  1. Old rbc's are removed from blood by macrophages in spleen and liver

  2. Hemoglobin is broken down

  3. Globin is broken down into amino acids

  4. Hemoglobin's iron is recycled

  5. Heme is converted to bilirubin

  6. 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: fight infections, remove dead cells and debris by phagocytosis
• Types of Leukocytes


  • Granulocytes: Neutrophils, Eosinophils, Basophils
  • Agranulocytes: Monocytes, Lymphocytes
• Platelets


  Blood clotting cells, produced in red bone marrow
• Hematopoiesis


  Process of blood cell formation, In an infant occurs in liver, thymus gland, spleen, lymph nodes, and red bone marrow, In adults occurs mainly in red bone marrow, Stem cell: original cell line
• Blood Loss


  When blood vessels are damaged, blood can leak into other tissues and disrupt normal function, Blood that is lost must be replaced by production of new blood or by a transfusion
• Preventing Blood Loss


  • Vascular spasm: temporary constriction of blood vessel
  • Platelet plugs: can seal up small breaks in blood vessels
  • Blood clotting (coagulation)
• Blood Clotting


  Blood can be transformed from a liquid to a gel, 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
• Three-Phase Process of Hemostasis

  1. Phase 1: Vascular spasm constricts the vessel

  2. Phase 2: Platelets stick together plugging the site

  3. Phase 3: Clot formation starts: 1. Enzyme cascade results in activation of Factor X, 2. Factor X converts prothrombin in plasma to thrombin, 3. Thrombin converts fibrinogen, a plasma protein, to fibrin threads, 4. Fibrin forms a net that entangles cells and platelets, forming a clot
• Steps in Clot Formation

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

  2. Prothrombinase (clotting factor) 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)
• Control of Clot Formation

  Clots need to be controlled so they don't spread throughout the body, Anticoagulants: prevent clots from forming, Ex. 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

  1. Clot retraction: condensing of clot, serum in plasma is squeezed out of clot, helps enhance healing

  2. Fibrinolysis: process of dissolving clot, plasminogen (plasma protein) breaks down clot (fibrin)
• Blood Reactions


  Injury or surgery can lead to a blood transfusion, Transfusion reactions/Aggulination: clumping of blood cells (bad), Antigens: molecules on surface of erythrocytes, Antibodies: proteins in plasma
• ABO Blood Groups


  • Type A, Type B, Type AB, Type O
  • Antigen: A, B, A&B, None
  • Antibodies: Anti-B, Anti-A, None, Anti-A&B
  • Common: 2nd, 3rd, 4th, 1st
• Blood Type Compatibility


  • 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
• Agglutination: Clumping of foreign cells by plasma proteins, When blood of incompatible types mixes, the immune system attacks the unfamiliar molecules
• Rh Blood Group


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


  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
• Diagnostic Blood Tests


  • Complete blood count, Hematocrit, Hemoglobin, Prothrombin time, White blood cell count, White blood cell differential count
• White Blood Cell Disorders

  • Leukopenia: low wbc count, caused by radiation, chemotherapy drugs, tumors, viral infections
  • Leukocytosis: high wbc count, caused by infections and leukemia