Immunology: Specific Defenses 40-2 Continues….

SPECIFIC DEFENSE: 3 rd Line If the 1 st (skin) and 2 nd (Inflammatory Response) lines of defense don’t work, an Immune Response is started  Pathogens are coated with antigens  2 types of Immune cells (WBC’s) recognize pathogens B cells: fight pathogens/antigens in body fluids T cells: fight abnormal cells and pathogens inside living cells

B Cells Attack!!!! When a pathogen enters the body: 1. B cells recognize the antigens and divide rapidly (Think the size of an army) 2. Many B cells produce antibodies (proteins that bind to antigens; these markers tell the body where the “bad guys” are) 3. Other B cells turn into memory cells. If the pathogen attacks the body a second time; these cells divide rapidly and produce mass amounts of antibodies

Antibodies These proteins are “Y” shaped in structure Each branch of the “Y” can bind to an antigen Antibodies are specific for antigens  Similar to the lock and key model Healthy adults can produce about 100 million different types of antibodies!

T Cells Attack!!!!! Once the antibodies are attached to the pathogens, Natural Killer T cells destroy the pathogen Other T cells may help activate Killer T cells or Memory T cells (which act the same way as Memory B Cells) Killer T cells kill pathogens found inside other cells as well as body cells gone bad

Passive vs. Acquired Immunity Passive Immunity:  Any time Antibodies are injected or introduced into an organism, it is passive immunity.  The immunity is given to the organism without any work being done Acquired Immunity  Requires the organism to make Antibodies  Can be the result of previous infection  Often the result of Vaccination Vaccines are weakened or dead versions of a live more harmful pathogen

Immune system goes wrong…. Allergies: Overreactions of the immune system…normally the body is trying to kill something that is not harmful  The body produces Histamines which cause sneezing, itchy eyes, running nose etc…  Treatments include antihistamines Asthma: A severe respiratory allergic response in which the airways become inflamed  There is not cure but many treatments including steroids Autoimmune Disorders: Sometimes the body doesn’t recognize its own cells and attacks them.  Examples include: Rheumatoid arthritis, Multiple Sclerosis, AIDS and Type I Diabetes