Quarter 4

• Blood


  The only fluid tissue in the human body that transports nutrients, wastes, hormones, and body heat through blood vessels
• Components of blood


  • Formed elements (living cells)
  • Plasma (nonliving fluid matrix)

  
• Characteristics of blood


  • Sticky, opaque fluid
  • Heavier and thicker than water
  • Color range (oxygen-rich = scarlet red, oxygen-poor = dull red/purple)
  • Metallic, salty taste
  • pH is slightly alkaline (between 7.35 and 7.45)
  • Temperature is slightly higher than body temp (at 38℃ or 100.4℉)
• Volume of blood


  About 5-6 liters or 6 quarts of blood in a healthy adult, makes up 8% of body weight
• Plasma


  90% water; straw-colored fluid that includes dissolved substances like nutrients, salts, respiratory gases, hormones, plasma proteins, and waste products
• Plasma proteins


  Most abundant solutes in plasma, most are made by the liver (except for antibodies and protein-based hormones)
• Examples of plasma proteins

  • Albumin (important blood buffer and contributes to osmotic pressure)
  • Clotting proteins (help stem blood loss when a blood vessel is injured)
  • Antibodies (help protect the body from pathogens)

  
• Erythrocytes (Red Blood Cells)

  • Main function is to carry oxygen
  • Anucleate (no nucleus)
  • Contain few organelles; lack mitochondria
  • Make ATP by anaerobic means
  • Essentially "bags" of hemoglobin
  • Shaped like biconcave discs

  
• Hemoglobin


  An iron-bearing protein that binds oxygen, each hemoglobin molecule can bind 4 oxygen molecules, each erythrocyte has 250 million hemoglobin molecules

  
• Homeostatic imbalances of erythrocytes

  • Anemia (decrease in oxygen-carrying ability of blood due to lower than normal number of RBCs or abnormal/deficient hemoglobin content)
  • Polycythemia (excessive or abnormal increase of RBCs)

  
• Types of anemia


  • Hemorrhagic (sudden hemorrhage)
  • Hemolytic (lysis of RBC as a result of bacterial infections)
  • Pernicious (lack of vitamin B12)
  • Aplastic (depression/destruction of bone marrow)
  • Iron-deficiency (lack of iron in diet or slow/prolonged bleeding)
  • Sickle cell (genetic defect leads to abnormal hemoglobin)

  
• Leukocytes (White Blood Cells)


  Crucial in the body's defense against disease, complete cells with nucleus and organelles, able to move into and out of blood vessels, respond to chemicals released by damaged tissues

  
• Homeostatic imbalances of leukocytes

  • Leukocytosis (excessive production of normal WBCs)
  • Leukopenia (abnormally low WBC count)
  • Leukemia (bone marrow becomes cancerous)

  
• Types of leukocytes


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

  
• Types of granulocytes


  • Neutrophils
  • Eosinophils
  • Basophils
• Types of agranulocytes


  • Lymphocytes
  • Monocytes
• Platelets/Thrombocytes


  Fragments of megakaryocytes, needed for clotting process, initiate clotting process by clinging to torn areas

  
• Hematopoiesis


  1. The process of blood cell formation that occurs in red bone marrow (myeloid tissue)

  2. All blood cells are derived from a common stem cell hemocytoblast

  3. Hemocytoblasts form lymphoid stem cell (produces lymphocytes) and myeloid stem cell (can produce all other formed elements)

  
• Formation of RBCs


  1. Wear out in 100-120 days, replaced by division of hemocytoblasts in the red bone marrow

  2. Reticulocytes (young RBCs) enter the blood to become oxygen-transport erythrocytes

  3. Erythropoietin (hormone produced by kidneys) controls the rate of RBC production

  
• Formation of WBCs and platelets

  Hormones like colony stimulating factors (CSFs), interleukins, and thrombopoietin prompt bone marrow to generate leukocytes and platelets

  
• Hemostasis


  A fast and localized process of stopping the bleeding that results from a break in a blood vessel

  
• Three phases of hemostasis

  1. Vascular spasms occur

  2. Platelet plug forms

  3. Coagulation events occur

  
• Disorders of hemostasis


  • Undesirable clotting (thrombus, embolus)
  • Bleeding disorders (thrombocytopenia)

  
• PF3 (a phospholipid) interacts with


  1. TF, blood protein clotting factors, and calcium ions

  2. Triggers a clotting cascade
• Prothrombin activator converts


  Prothrombin to thrombin (an enzyme)
• Thrombin joins


  Fibrinogen proteins into hairlike molecules of insoluble fibrin

  
• Fibrin forms


  A meshwork (the basis for a clot)
• Within the hour, serum is squeezed from the clot as it retracts to pull


  Edges of the blood vessel together

  
• Serum


  Plasma minus clotting proteins
• Undesirable Clotting: Thrombus - A clot that develops and persists in an unbroken blood vessel, can be deadly in areas such as the lungs
• Undesirable Clotting: Embolus - A thrombus that breaks away and floats freely in the bloodstream, can later clog vessels in critical areas such as the brain

  
• Thrombocytopenia


  Insufficient number of circulating platelets, arises from any condition that suppresses the bone marrow, even normal movements can cause bleeding from small blood vessels that require platelets for clotting, evidenced by petechiae (small purplish blotches on the skin)

  
• Hemophilia


  Hereditary bleeding disorder, normal clotting factors are missing, minor tissue damage can cause life-threatening prolonged bleeding

  
• Large losses of blood have serious consequences: Loss of 15-30% causes pallor and weakness, Loss of over 30% causes severe shock, which can be fatal
• Blood transfusions are given for substantial blood loss to treat severe anemia or for thrombocytopenia

  
• Antigens


  Genetically determined proteins present in the blood, substances that the body recognizes as foreign and that the immune system may attack, most antigens are foreign proteins, we tolerate our own self-antigens, there are over 30 common RBC antigens

  
• Antibodies


  The "recognizers" that bind foreign antigens, blood is typed by causing antibodies that will cause blood with certain proteins to clump (agglutination) and lyse

  
• Transfusion reactions: Lysed RBCs release hemoglobin into the bloodstream, freed hemoglobin may block kidney tubules, causing kidney failure and death, fever, chills, nausea, and vomiting can also occur

  
• ABO Blood Group


  Based on the presence of 2 antigens: Type A, Type B, Type AB, Type O

  
• Rh Blood Group


  Named for 1 of the 8 antigens (agglutinogen D) identified in Rhesus monkeys, if your blood type is negative, your blood cells lack Rh protein, most Americans are Rh+, carrying the Rh antigen, anti-Rh antibodies are not automatically formed by the blood of Rh- individuals, Rh-related problem during pregnancy: danger occurs only when the mother is Rh- and the father is Rh+, and the child inherits the Rh+ factor