nonspecific immunity

• mechanical defenses


  1. skin as a shield; dry dead layer inhospitable, nutrient-depleted, tightly packed cells, normal flora, high osmotic pressure

  2. mucus membranes constantly trap and wash potential pathogens away; respiratory, gastrointestinal, genital

  3. tears constantly wash potential pathogens away

  4. cilia: ciliary escalator

  saliva constantly washes potential pathogens away

  5. urine

  6. feces

  7. vomiting, diarrhea
• chemical defenses

  1. sebum

  2. salt accumulation

  3. lysozymes in tears, perspiration, and saliva

  4. normal flora

  5. low pH

  6. transferrin in blood/lactoferrin in breast milk
• sebum's role


  secreted on the skin; low pH, thus discouraging pathogen colonization
• salt accumulation role

  on the skin from evaporated perspiration; increases the osmotic pressure, thus discouraging growth
• lysozyme's role


  found in tears, perspiration, and salvia; digests gram + cell walls
• normal flora's role

  reduce pH of skin and vagina, prevent colonization of intestinal and genital tracts
• low pH's role

  stomach's low pH is antimicrobial
• transferrin/lactoferrin's role


  found in milk and breast milk; bind to free iron, preventing microbes from receiving it
• biological defenses

  phagocytosis, natural killer (NK) cells, inflammation, fever
• phagocytosis


  different white blood cells (leukocytes) that bind, ingest, and destroy foreign bodies
• natural killer (NK) cells

  recognize, attack, and kill infected host cells or cancer cells by recognizing abnormal membrane proteins
• inflammation


  They release chemical factors that cause vasodilation and increased permeability of blood vessels.
• Why does vasodilation occur during inflammation?

  To increase blood flow for more immune cells to reach the injured area.
• Why does increased permeability of blood vessels occur during inflammation?

  To allow immune cells and proteins to diffuse into the injured area.
• fever


  moderate fever stimulates immune cells to faster differentiation and growth and has an inhibitory effect on some pathogens (heat shock) putting them into a temporary lag phase
• complement proteins

  2 antibodies bound to an antigen forces a conformational change on the antibody proteins. Makes them receptors for the complement proteins to bind and get activated
• activated complement proteins effect

  1. release of histamine causing inflammation

  2. chemotaxins

  3. acts as opsonins

  5. cytolysis
• chemotaxins


  attracts phagocytes
• opsonins


  allows phagocytes to better grab hold so they can ingest
• cytolysis

  causes cells to lyse (burst)
• interferons


  proteins (cytokines) secreted by T cells and other cells to aid and regulate the immune response