Function 4: Protect and defend against invaders Immune System/Lymphatic System Important Terms and Parts: Disease: any disruption in normal structure or function of cells, tissues, or organ systems Infectious: caused by a virus or microorganism which are called pathogens. These diseases can be spread to other people. Noninfectious: caused by genetic disorders, birth defects, organs wearing out, abnormal tissue growth, etc. These cannot be spread to others. Nonspecific Immune Response: general things that the immune system does to protect you e.g. skin acts as a physical/chemical barrier, chemicals in tears, inflammation (swelling), fever, phagocytic white blood cells eat invaders Specific Immune Response: something that the immune system does for a certain pathogen e.g. Lymphocytes (white blood cells): T-cells and B-cells that recognize a certain pathogen and remember it (immunity). Thymus gland: makes lymphocytes Tonsils: contain lymphocytes and protect against infections Spleen: filters and stores blood, removes damaged and worn out red blood cells and platelets