Immunity & the Immune Response

I.Immunity 1.Immunity is the ability to defend itself against pathogens, (such as bacteria, viruses, fungi, protozoans, toxins and cancerous tumors) 2.Two forms: a.Natural- not specific to a particular disease i.Ex. Macrophage- concentrated in lungs and digestive system; ingesting and digesting any pathogen they encounter

b. Acquired- body’s response to a specific pathogen i. passive acquired- results when a person receives immunity from another human or animal (ex. Mother’s antibodies being passed to baby through placenta) ii. Active acquired- develops following direct exposure to the pathogenic agent  Stimulates the body’s immune response  Immunizations/vaccinations are special types of acquired immunity by being exposed to a modified pathogen

II. Immune Response 1.Pathogens are recognized as foreign because they have proteins that are different from ours 2.Foreign proteins are called antigens and they stimulate the immune response 3.Immune response has 2 different processes: a.Humoral (or anitbody-mediated) immunity b.Cellular (or cell-mediated immunity)

A. Humoral Immunity 1.Production of B lymphocytes (or B cells) 2.B cells respond to antigens by producing an antibody to form an antigen-antibody complex 3.Complex either targets the pathogen for phagocytosis, or prevents it from damaging healthy tissues

B. Cellular Immunity 1.Involves the production of T cells and natural killer (NK) cells 2.These cells are cytoxic and physically attack ad destroy pathogenic cells

III. Standard Precautions 1.Health care workers are exposed to a large # of pathogens and can become infected 2.Nosocomial infection- infection resulting from a pathogen in a hospital 3.Cross infection- occurs when a patient or worker acquires a pathogen from another patient or worker 4.Reinfection-gets the same pathogen again

5. Self inoculation- occurs when a person becomes infected in a different part of the body by a pathogen from another part of his or her own body 6. OSHA (Occupational Safety and Health Administration) came about when HIV and Hep B appeared in late 80s  Mandatory guidelines (aka Standard Precautions) to ensure that all employees at risk of exposure to bodily fluids are provided with protection