Third Line of Defense Immune Response (Specific Defense)

Immune Response (Specific Defense) A series of specific defenses that attack a particular disease-causing agent is called an Immune Response

Two Divisions of the Immune System Humoral Immunity Cell-mediated Immunity Antibodies mark infected cells for death Cells attack infected cells

Cells of the Immune System Two types of cells recognize specific antigens: B Lymphocytes and T Lymphocytes B-Cell T-Cell

Antigen A substance on the surface of a pathogen that triggers an immune response is called an Antigen (Germ’s fingerprint)

Antibody Plasma cells produce antibodies Antibodies circulate in the bloodstream and attack the pathogen causing the infection

Antibody Antibodies are proteins that recognize and bind to antigens

Antibody Antigen-Binding Sites The site that the antibody binds to the antigen is called the antigen-binding site

Memory Cells Some B-cells become memory cells, which are the antibody factory pre-programmed to respond to a returning antigen (i.e. vaccination)

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Humoral Immunity Plasma Cell Antibodies B-Cell Pathogens (Bacteria, Virus, Fungi, Worms, Foreign Proteins) 3. B-cells become Plasma cells, which produce antibodies against the antigen Antibodies bound to pathogen 2. B-cell recognizes antigen on pathogen 4. Antibodies bind to the pathogen, marking it for death 1. Pathogen invades the body

Humoral Immunity B-Cells - provides immunity against pathogens found in body fluids.