Immune System

Disease Any change in the body not due to injury that disrupts homeostasis Pathogens = Sickness makers How do we know pathogens make you sick?

Koch’s Postulates 1.The suspected causal organism must be constantly associated with the disease. 2.The suspected causal organism must be isolated from an infected organism and grown in pure culture. 3.When a healthy susceptible host is inoculated with the pathogen from pure culture, symptoms of the original disease must develop. 4.The same pathogen must be re-isolated from the organism infected under experimental conditions.

Lyme Disease Risk

Lyme Disease Etiology Allen Steere (1975) Yale University 39 children from Lyme Connecticut All had pain and joint inflammation All had insect bites and rashes Dr. Willy Burgdorfer found spirochete in ticks Steere found same bacterium in his patients

Non-Specific Immunity 1 st Line of Defense Skin Mucous membranes Saliva Mucus Nasal hair Tracheal cilia Stomach acid Sweat Tears

Non-Specific Immunity 2 nd Line of Defense Phagocytes Natural killer (NK) cells Inflammatory response Pyrogens (Reset thermostat in hypothalamus) Complement proteins Interferon (Prevents viral replication) Lysozyme (Pokes holes in bacterial cell walls)

Non-Specific Immunity Complements identify antigen Granulocytes attack antigen creating pus Macrophages perform phagocytosis on bacteria

Inflammatory Response 1.Damaged tissue releases histamine 2.Capillaries become “leaky” 3.Blood flow increases to area 4.Clotting factors and phagocytes released into the wound 5.Phagocytes engulf bacteria, cellular debris, & dead cells 6.Macrophages release cytokines which attract immune system cells 7.Platelets seal the wound with a clot

Specific Defenses Humoral immunity – immunity against pathogens in body fluids (blood and lymph) Immune response carried out by lymphocytes Cell-Mediated immunity – Antibody production

Antibodies Antibody = a protein that helps to destroy pathogens Substrate specific Cause agglutination which attracts phagocytes Made by plasma cells Plasma cells made by b-lymphocytes

Humoral Immunity

IgM IgA IgG Antibodies

Cell Mediated Immunity Active immunity - vaccination with antigen (lasts for years) Passive immunity – transferring antibodies from one person to another (lasts several weeks)

Dr. Edward Jenner