Defenses against infection 35.2 Defenses against infection

Nonspecific defenses Skin Tears Lysozyme enzyme that breaks down bacterial cell walls Other secretions (like mucous) Inflammatory response Interferons Fever *first line of defense *second line of defense

Inflammatory response Infected areas become red and painful (inflamed)

Histamines Chemical that increases flow of blood and fluids to the affected area (p. 1015)

Interferons Proteins released by a host cell getting “attacked” by a virus that inhibits synthesis of viral proteins

Fever Increase body temperature Slows down or stops the growth of some pathogens ***remember…a lot of bacteria/ pathogens can’t withstand high heat!***

Specific defenses Immune system’s specific defenses distinguish between “self” and “other,” and they inactivate or kill any foreign substance or cell that enters the body. *respond to a particular pathogen!*

Immune response Body doesn’t recognize something Goes into an IMMUNE RESPONSE Specific recognition, response and memory to pathogens

Antigens vs. antibodies Antigen any foreign substance that can stimulate an immune response Antibodies tags antigens for destruction by immune cells

Lymphocytes B lymphocytes and T lymphocytes are the main working cells of the immune systems

The specific immune response has two main styles of action…humoral immunity and cell-mediated immunity Humoral refers to the immune response that happens in body fluids (B cells) Cell-mediated (T cells) defends the body against some viruses, fungi, and single- celled pathogens