Chapter 16 Tortora


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Chapter 16 Tortora

  1. 1. Chapter 16 Tortora Innate Immunity-Nonspecific Defenses
  2. 2. Types of immunity <ul><li>Innate immunity-defense present at birth </li></ul><ul><ul><li>Rapid response </li></ul></ul><ul><ul><li>No memory component </li></ul></ul><ul><ul><li>First line of defense and second line of defense is in this category </li></ul></ul><ul><li>Adaptive or specific immunity is the defense that kicks in once the innate has been breached </li></ul><ul><ul><li>This involves lymphocytes (T and B cells) </li></ul></ul>
  3. 3. First line of Defense <ul><li>Skin and mucous membrane </li></ul><ul><li>Contain both physical and chemical features </li></ul><ul><li>Physical-intact skin is First barrier! </li></ul><ul><ul><li>Epidermis has keratin (protein) that helps waterproof skin </li></ul></ul><ul><ul><li>Cells are closely packed and dry usually </li></ul></ul><ul><li>Mucous membrane-line openings to outside </li></ul><ul><ul><li>Mucus keeps these openings moist </li></ul></ul><ul><ul><li>Some bacteria can penetrate the membrane like Treponema pallidum </li></ul></ul>
  4. 4. Physical barriers continued <ul><li>Lacrimal apparatus-produce and drain tears </li></ul><ul><li>Tears wash eye and cleans it </li></ul><ul><li>Saliva also washes out mouth and dilutes the number of bacteria </li></ul><ul><li>Very small hairs found in nose help filter air and trap bacteria </li></ul><ul><li>Cilia in lower respiratory tract move dust and microorganisms trapped in mucous upward toward throat and you swallow it (cigarettes are toxic to this ciliary escalator ) </li></ul>
  5. 5. More physical barriers <ul><li>Epiglottis-prevents microbes from entering lungs during swallowing </li></ul><ul><li>Urine-cleans urethra </li></ul><ul><li>Vaginal secretions-remove microbes from female </li></ul><ul><li>Defecation-removes waste </li></ul><ul><li>Vomiting-rids the body of harmful substances </li></ul>
  6. 6. Chemical factors <ul><li>Sebaceous glands produce sebum which prevents hair from drying out and forms a protective film over skin </li></ul><ul><ul><li>Contain unsaturated fatty acids which inhibit growth of some pathogens and fungi </li></ul></ul><ul><ul><li>Helps provide a pH of 3-5 which also discourages bacterial growth </li></ul></ul><ul><li>Sweat glands produce perspiration which helps flush bacteria from surface of skin </li></ul><ul><li>Contains lysozyme which breaks down cell wall of gram positive and some gram negative </li></ul>
  7. 7. Chemical continued <ul><li>Lysozyme is also in tears, saliva, nasal secretions, and tissue fluids </li></ul><ul><ul><li>Alexander Fleming was studying lysozyme when he accidentally discovered penicillin </li></ul></ul><ul><li>Gastric juice is a mixture of HCl, enzymes and mucus and provides a pH of 1-3 </li></ul><ul><ul><li>Some bacteria are protected by food or are not bothered by this acid ( Clostridium botulinum and Staphylococcus aureus ) </li></ul></ul><ul><ul><li>some like the acid ( Helicobacter pylori ) </li></ul></ul>
  8. 8. Second line of defense <ul><li>Blood includes plasma (liquid portion) and formed elements (solid portion) </li></ul><ul><li>During an infection the total number of WBC’s increase (leukocytosis) or decrease (leukopenia) </li></ul><ul><li>Determine white blood cell count with differential white blood cell count </li></ul><ul><li>See table 16.1 for normal values and photos </li></ul>
  9. 9. Types of WBC’s <ul><li>Divide into 2 categories: </li></ul><ul><li>1. granulocytes-large granules in cytoplasm that are present during staining </li></ul><ul><ul><li>Neutrophils-or polymorphonucleocytes (PMN’S) </li></ul></ul><ul><ul><ul><li>Enter early in infection, can leave blood and enter infected tissue </li></ul></ul></ul><ul><ul><ul><li>Most abundant type and are highly phagocytic </li></ul></ul></ul><ul><li>http:// </li></ul>
  10. 10. Granulocytes continued <ul><li>Eosinophils-can leave blood too </li></ul><ul><li>Major function is to produce toxic proteins against parasites </li></ul><ul><li>Increase during parasite infestation and allergy </li></ul><ul><li> </li></ul><ul><li>Basophils-release histamine and other substances that are important in allergy and inflammation response </li></ul><ul><li> </li></ul>
  11. 11. Agranulocytes <ul><li>2. Agranulocytes-no visible granules in cytoplasm after staining </li></ul><ul><li>Include monocytes-phagocytic after mature into macrophages and leave blood </li></ul><ul><ul><li>One reason your lymph nodes swell during infection! </li></ul></ul><ul><ul><li>Destroy microbes and old blood cells </li></ul></ul><ul><li>The other type is the lymphocyte-including T, B, and Natural Killer (NK) cells-these have their own chapter </li></ul>
  12. 12. Phagocytosis <ul><li>Click here for a video clip of phagocytosis </li></ul><ul><li> </li></ul><ul><li>Watch the video and remember the steps! </li></ul><ul><li>Order of importance-initial infection-neutrophils are first then macrophages take over </li></ul><ul><li>Never Let Monkeys Eat Bananas! (order of WBC’s in normal differential) </li></ul>
  13. 13. Steps in phagocytosis <ul><li>Chemotaxis </li></ul><ul><li>Ingestion </li></ul><ul><li>Digestion (then releases waste after ‘eating’) </li></ul><ul><li>Remember to watch the movie. This one has a little more ‘kick’ </li></ul><ul><li>OR </li></ul>
  14. 14. Microbial evasion of phagocytosis <ul><li>Some have M protein and or capsules that interfere with adherence </li></ul><ul><ul><li>Streptococcus pneumoniae (must trap these to engulf) </li></ul></ul><ul><li>Some are ingested but aren’t killed in phagocyte </li></ul><ul><ul><li>Staphylococcus may kill phagocyte by producing leukocidins </li></ul></ul><ul><li>Some can live inside phagocyte </li></ul><ul><ul><li>Coxiella burnetti (Q fever), Listeria monocytogenes, Shigella, Rickettsia can escape the phagocyte </li></ul></ul><ul><ul><li>Mycobacterium tuberculosis , HIV, Chlamydia, Plasmodium can multiply inside the phagocyte and kills the phagocyte </li></ul></ul>
  15. 15. Inflammation <ul><li>Triggered by damage to tissue </li></ul><ul><li>4 signs </li></ul><ul><ul><li>Pain (dolor) </li></ul></ul><ul><ul><li>Redness (rubor) </li></ul></ul><ul><ul><li>Swelling (tumor) </li></ul></ul><ul><ul><li>Heat (calor) </li></ul></ul><ul><ul><li>May have a 5 th sign-loss of function </li></ul></ul><ul><li>Functions are to remove infectious agent or limit it’s effects on body and repair or replace damaged tissue </li></ul>
  16. 16. Steps in inflammation <ul><li>1. Blood vessels dilate (vasodilation) and increase blood flow (causes rubor and calor) </li></ul><ul><li>Increased permeability due to dilated vessels is responsible for edema </li></ul><ul><li>Vasodilation and increased permeability are caused by histamine and kinins </li></ul><ul><li>Prostaglandins are released by damaged cells and intensify effect of histamine and kinins </li></ul><ul><li>Leukotrienes are produced by mast cells and basophils and increase permeability and help phagocytes attach to pathogens </li></ul><ul><li>Clots may form around the infection and prevent spread of pathogen or toxin and help form pus </li></ul>
  17. 17. Steps continued <ul><li>2. phagocytes migration and phagocytosis </li></ul><ul><li>Phagocytes stick to inner surface of blood vessels (margination) and squeeze through endothelial lining to enter infected area </li></ul><ul><li>This is called emigration or diapedesis </li></ul><ul><li>3. tissue repair-dead and damaged tissue is replaced </li></ul><ul><li>If only parenchyma (functional part) cells are involved the reconstruction will be perfect (no scar) </li></ul><ul><li>If stroma (supporting connective tissue) is involved scar tissue results </li></ul>
  18. 18. Fever <ul><li>Abnormally high temperature in response to infection, toxins, etc </li></ul><ul><li>Hypothalamus controls body temperature </li></ul><ul><li>Pyrogens reset this thermostat </li></ul><ul><li>Body responds by shivering, increased metabolism, and blood vessels constriction </li></ul><ul><li>Body temp is climbing but skin is cold causing the chill </li></ul><ul><li>After infection the blood vessels dilate and sweating occurs, helping lower temperature </li></ul><ul><li>Crisis is when the person sweats and skin becomes warm (fever is breaking) </li></ul><ul><li>Fever is good defense up to a point </li></ul><ul><li>Death results if fever gets 112 degrees </li></ul>
  19. 19. Antimicrobial substances <ul><li>Complement system-complex series of 30 proteins produced by liver that circulate in blood and tissues </li></ul><ul><li>Help destroy microbes by cytolysis, inflammation, and phagocytosis </li></ul><ul><li>These proteins stay inactive until split into fragments called a and b </li></ul><ul><li>Use C to designate which is which C1-C9 </li></ul><ul><li>Acts as a cascade, one triggers another. </li></ul><ul><li>C3 is one of the most important! </li></ul><ul><li>Have 3 pathways: classical, alternative, and lectin </li></ul><ul><li>Some bacteria can resist complement (capsules) </li></ul>
  20. 20. More antimicrobial substances <ul><li>Interferon-IFN’s antiviral proteins that are produced by certain cells like lymphocytes and macrophages AFTER viral stimulation </li></ul><ul><li>These proteins interfere with viral replication </li></ul><ul><li>Have found 3 types so far: alpha, beta, and gamma </li></ul><ul><li>Produced by viral infected cells and spread to neighboring uninfected cells, inducing them to make antiviral proteins that disrupt viral multiplication </li></ul><ul><li>Studying these as possible cure for cancer, etc. </li></ul>
  21. 21. One more time! <ul><li>Transferrins-iron binding proteins that inhibit bacteria growth by reducing the amount of available iron </li></ul><ul><ul><li>Iron overload can suppress chemotaxis and phagocytosis and increase risk of infection! </li></ul></ul><ul><li>Antimicrobial peptides-newly discovered, produced by mucous membrane cells and phagocytes </li></ul><ul><ul><li>These bind to microbial plasma membrane and cause lysis </li></ul></ul>