Immune System and Disease CHAPTER 35 35.1 Infectious disease can be caused by viruses, fungi, bacteria, protists, and parasites. Some diseases are spread through coughing or physical contact with another person. Some diseases are spread through contaminated water or food or infected animals. 35.1 Continued Infectious diseases: occur when microorganisms cause physiological changes that disrupt normal body functions. Germ theory of disease: microorganisms that were commonly called germs. Koch’s postulates: rules that led Koch to develop rules for identifying microorganisms that cause a specific disease. Zoonosis: any disease that can be transmitted from animal to human. Vectors: carriers that transport pathogens. 35.2- Defenses Against Infection The immune systems specific defenses distinguish between self and other, and they inactivate or kill foreign substances or cells that enter the body. The specific immune response has two main styles of action- humoral and cell mediated immunity. Nonspecific defenses include the skin, tears, inflammatory response, interferon's, and fever. 35.2 Continued Inflammatory response: causes infected areas to become red and painful, or inflamed Histamines: increase the flow of blood and fluids to the affected area. Interferons: interfere with viral growth. Fever: increased body temperature that occurs in response to infection. Immune response: specific recognition, response, and memory. Antigen: any foreign substance that can stimulate an immune response. Antibodies: to tag antigens for destruction by immune cells. Humoral immunity: depends on the action of antibodies that circulate in the blood and lymph. Cell mediated immunity: depends on the action of macrophages and several types of T cells. 35.3- Fighting Infectious Disease Vaccination stimulates the immune system with an antigen. Antibodies produced against a pathogen by other individuals can be used to produce temporary immunity. Antibodies can kill bacteria and some antiviral medications can slow down the viral activity. The immune system produces memory B cells and memory T cells that speed up and strengthen the body's response to a repeated infection or disease. Two major reasons for the emergence of new disease are the ongoing merging of human and animal habitats and the increase in the exotic animal trade. 35.3 Continued Vaccination: injection of a weakened, or a similar but less dangerous, pathogen to produce immunity. Active Immunity: immunity that develops as a result of natural or deliberate exposure to an antigen. Passive Immunity: temporary immunity that develops as a result of natural or deliberate exposure to an antibody. 35.4- Immune System Disorders A strong immune response to harmless antigens can produce allergies and asthma. When the immune system attacks the body’s own cells it produces an autoimmune disease. 35.4 Continued Allergy: trigger an inflammatory response causing mast cells to release histamines. Asthma: is a chronic disease in which air passes narrow, causing wheezing, coughing and difficulty breathing.