A&P Exam 7

• Immune System


  Not an organ system, but a cell population that inhibits all organs and defends the body from agents of disease
• Lymphatic System


  • Network of organs and vein-like vessels that recover fluid
  • Inspect it for disease agents
  • Activate immune responses
  • Return fluid to the bloodstream
• Fluid recovery


  Fluid continually filters from the blood capillaries into the tissue spaces
• Immunity


  1. Excess filtered fluid picks up foreign cells and chemicals from the tissues

  2. Passes through lymph nodes where immune cells stand guard against foreign matter

  3. Activates a protective immune response
• Lipid absorption


  Lacteals in small intestine absorb dietary lipids that are not absorbed by the blood capillaries
• Pathogens


  Agents capable of producing disease, including viruses, bacteria, and fungi
• Lymph


  The recovered fluid, clear, colorless fluid, similar to plasma, but much less protein
• Lymphatic vessels


  Pathway: lymphatic capillaries > collecting vessels >lymphatic trunks > 2 collecting ducts > subclavian veins

  
• Lymphatic Tissue


  • Composed of aggregates of lymphocytes and macrophages that populate many organs in the body
• Lymphatic Organs


  • Defense cells are especially concentrated in these organs
  • Separated from surrounding organs by connective tissue capsules
• Lymphatic Capillaries (terminal lymphatics)

  • Penetrate nearly every tissue of the body
  • Absent from cartilage, cornea, bone, and bone marrow
  • Closed at one end
  • Gaps between cells are large enough to allow bacteria and cells to enter the lymphatic capillary
• Lymphatic Vessels


  • Lymphatic capillaries
  • Collecting Vessels
  • Eleven lymphatic trunks
  • Two collecting ducts
  • Subclavian veins
• Types of lymphatic cells

  • Neutrophils
  • Natural Killer cells
  • T Lymphocytes
  • B Lymphocytes
  • Macrophages
  • Dendritic Cells
  • Reticular Cells
• Lymphatic Tissues


  • Diffuse Lymphatic tissue - simplest form, prevalent in body passages open to the exterior
  • Dense masses of lymphocytes and macrophages
• Primary lymphatic organs


  • Red bone marrow
  • Thymus
• Secondary lymphatic organs


  • Lymph nodes
  • Tonsils
  • Spleen
• Lymph nodes


  • Serve two functions: cleanse the lymph and act as a site of the T and B cell activation
• Tonsils


  • Patches of lymphatic tissue located at the entrance of the pharynx, guard against ingested or inhaled pathogens
• Spleen


  • The body's largest lymphatic organ, healthy red blood cells come and go, old/fragile RBCs are destroyed, blood cell production in fetus and very anemic adults, monitors blood for foreign antigens and keeps an army of monocytes for release when needed, stabilizes blood volume through plasma transfers to lymphatic system
• Three lines of defense against pathogens (innate immunity)


  • First line: skin and mucous membranes
  • Second line: leukocytes and macrophages, antimicrobial proteins, natural killer cells, inflammation and fever
  • Third line: defeats a pathogen and leaves boy with a memory of it so it can defeat it faster in the future
• Innate Immunity


  Born with, guards equally against a broad range of pathogens, local, nonspecific, lacks memory
• Adaptive Immunity


  Body must develop separate immunity to each pathogen, body adapts to a pathogen and wards it off more easily upon future exposure (memory)
• Leukocytes and Macrophages


  • Neutrophils
  • Eosinophils
  • Basophils
  • Monocytes
  • Lymphocytes
• Monocytes and Macrophages


  • Monocytes emigrate from the blood into connective tissues and transform into macrophages
  • Macrophage system - all the body's avidly phagocytic cells, except leukocytes
• Natural Killer Cells


  • Continually patrol body looking for pathogens and diseased host cells, attack and destroy bacteria, transplanted cells, cells infected with virus, cancer cells
• Inflammation


  • Local defense response to tissue injury, including trauma and infection, priority is to prevent pathogens from spreading throughout body
• Four Cardinal Signs of Inflammation

  • Redness
  • Swelling
  • Heat
  • Pain
• Three major Processes of inflammation

  • Mobilization of body defense
  • Containment and destruction of pathogens
  • Tissue cleanup and repair
• Adaptive Immunity


  • Systemic Effect: throughout the body
  • Specificity: immunity directed against a particular pathogen
  • Memory: when reexposed to the same pathogen, the body reacts so quickly that there is no noticeable illness
• Two forms of adaptive immunity

  • Cellular (cell-mediated) immunity
  • Humoral (antibody-mediated) immunity
• Forms or Types of Immunity

  • Active - natural active immunity, artificial active immunity
  • Passive - natural passive immunity, artificial passive immunity
• Antigens


  Any molecule that triggers an immune response, characteristics enable body to distinguish "self" molecules from foreign ones
• Antibodies


  Protein of gamma globulin that reacts with an antigen and aids the body in protecting it from the antigens harmful effects
• Antibody classes


  • IgA, IgD, IgE, IgG, IgM
• Types of Lymphocytes


  • Natural Killer Cells (NK)
  • T Lymphocytes (T cells)
  • B lymphocytes (B Cells)
• Cellular Immunity


  • T lymphocytes directly attack and destroy diseased or foreign cells, the immune system remembers the antigens and prevents them from causing disease in the future
• Classes of T-cells


  • Cytotoxic
  • Helper
  • Regulatory
  • Memory
• Cellular and Humoral Immunity

  1. Recognition (recognize)

  2. Attack (React)

  3. Memory (Remember)
• Humoral Immunity


  • B Lymphocytes produce antibodies that bind to antigens and tag them for destruction by other means, more indirect method of defense than cellular immunity
• Immune System Disorders


  Immune response may be: too vigorous, too weak, misdirected against wrong targets