III. Specific Responses

A. Nonspecific responses   Occur the same way for every pathogen. 1. Inflammation – see previous section   2. Fever   a. occur when macrophages release chemical that cause the hypothalamus to increase the body’s temperature.   b. low fever causes the body to produce interferon and speed up the maturity rate of WBC’s. This allows WBC’s to quickly fight off infection.   c. High fevers cause the body to shut down all immune responses.

B. Specific responses   Occur differently for each type of pathogen.   1. Antigens are chemicals on the cell membrane (both normal cells and viruses) that allow the body to differentiate between it’s own cells and foreign cells.

  2. Specialized T and B cells become memory cells after they have been in contact with the antigen of the pathogen.   a. This provides the body with aquired immunity.   b. T and B cells will recognize the foreign cells antigen the second time it invades the body and be able to destroy it before you get sick.   c. memory cells give long term protection, are faster acting, and are more powerful

3. Cellular Immunity   a. Dependent on activated T cells to recognize antigens of pathogens on the surface of phagocytes.   b. T cells divide and differentiate into memory cells and activated cells.   c. Activated cells fight the current infection   d. memory cells are reserved for future infections.

4. Humoral Immunity   a. it occurs at the same time as the Cell-Mediated response   b. B cells engulf the pathogen and put the antigen of that pathogen on the surface of the cell membrane.   c. T cells bind to the B cell and activate it.

  d. B cells divide and become either activated cells or memory cells   1) activated cells make antibodies.   2) antibodies cause pathogens to clump together.   3) Phagocytes destroy the clumps.

C. Rejecting Foreign Tissue   1. All cells have markers on their surface.   2. Blood or Tissues are rejected when the body sees these as an foreign invader.   3. There are 1000’s of markers on a cell.   4. The less difference the better the chance of not rejecting the transplant.   5. Interferon and other drugs are given to trick the body.   6. Unfortunately these drugs weaken the immune system

D. Immunity and Vaccination   1. Vaccines   a. a solution that contains a weakened or dead pathogen or part of a pathogen.   b. antigens are present in the body after the vaccine is given   c. the immune system goes through a total response

  d. memory cells are left to fight the second exposure   e. vaccines are given for mumps, measles, diptheria, pertussis, tetanus etc.   f. booster shots may be required to restore immunity for some diseases after a time.

2. Problems of the Immune System   a. Allergies - physical response to an antigen   1) common substances: dust, grass, pet hair etc. cause mild reactions   2) some can be fatal: seafood, bee sting, nuts   3) the use of antihistimines counter the effects of histimine

  b. Asthma - narrowing of the bronchioles   1) over-reaction to particles in the air

  c. Auto-immune Disease - immune system attacks its own body cells as if they were pathogens.   1) This can effect certain organs and tissues:   Multiple Sclerosis - nervous system   Lupus - connective tissue   Crohns – digestive   Rheumatoid Arthritis - joints