Copyright Pearson Prentice Hall Biology I will understand the role of antibodies (molecular barrier) in the body's response to infection and based on this, know how a vaccine works. MT: Immune System Above: measles rash Below: muscle spasm from tetanus Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 40-2 The Immune System What is the function of the immune system? To protect against pathogens. Copyright Pearson Prentice Hall

40-2 The Immune System The immune system includes two general categories of defense mechanisms against infection: Specific defense Non-Specific defense Only detects certain pathogens Does not discriminate against pathogens – kill all pathogens Ex: antibodies, T cells, B cells Ex: skin, mucous, sweat glands, tears Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall What is an antigen? Antigen: any pathogen that activates the immune system Ex: virus, bacteria Antibodies attack antigens bad good Copyright Pearson Prentice Hall

AntiBODY = good protein AntiGEN = bad pathogen Antibody vs. Antigen AntiBODY = good protein AntiGEN = bad pathogen Antibody Antigen Copyright Pearson Prentice Hall

Steps to making an Antibody Pathogen (antigen) gets past skin, mucous, or tears into blood Antigen is detected by B-cells (a type of white blood cell) B-cells reproduce rapidly Some B-cells become plasma cells Some B-cells become memory cells Plasma cells release antibodies to attack antigens Memory cells stay in blood and hang out until the body is exposed to same antigen later so it can rapidly produce antibodies As antigens die, plasma cells die and stop producing antibodies Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Antibody structure Antigen binding site An antibody is shaped like the letter “Y” and has two identical antigen- binding sites. Antibody Antigen Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Specific Defenses Small differences in amino acids affect shapes of binding sites. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall How does a vaccine work? Vaccines (a weakened form of a pathogen) stimulate the immune system to create millions of plasma cells ready to produce specific types of antibodies. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Acquired Immunity Today, over 20 serious human diseases can be prevented by vaccination including: 1. measles (respiratory; coughing; virus) 2. mumps (swollen salivary glands or testes; virus) 3. hepatitis (inflammation of liver, mostly virus) 4. tetanus (severe muscle spasms; bacteria) 5. polio (muscle weakness; attacks nerves; viral) (Franklin D. Roosevelt) Copyright Pearson Prentice Hall