Understanding Stress, Immunity, and Disease.pdf

Understanding Stress, ImmUnderstanding Stress, Immunity, and Disease CHAPTER 6 Understanding Stress, Immunity, and Disease Lecture Outline I. Physiology of the Immune System The immune system consists of tissues, organs, and processes that protect the body from invasion by foreign material such as bacteria, viruses, and fungi. It also removes worn-out or damaged cells from the body. A. Organs of the Immune System The immune system includes lymph (circulating fluid that contains a type of white blood cell called lymphocytes) and lymph nodes (interspersed oval capsule structures) through which lymph circulates (see Figure 6.1). Various types of lymphocytes include T-cells, Bcells, and natural killer (NK) cells. The thymus, tonsils, and spleen are also involved with the production, maturation, or differentiation of the various types of lymphocytes. B. Function of the Immune System The immune system is the body’s defense against foreign invaders, and it must be virtually 100% effective in destroying invaders (see Figure 6.2). 1. Nonspecific Immune System Responses Phagocytosis (attack of foreign particles by granulocytes or macrophages) and inflammation (the sequence of events that restores damaged tissue) target a wide variety of invading particles. 2. Specific Immune System Responses Contact with invading microorganisms sensitizes T-cells, allowing the cytotoxic Tcells to subsequently recognize these invaders and create a specific immunity called cellmediated immunity. After coming into contact with an antigen, B-cells differentiate into plasma cells that manufacture specific antibodies that mark invading cells for later destruction (see Figure 6.3). Even after the invaders have been destroyed, the immune system keeps the critical information that allows future manufacture of antibodies, creating immunity to an invader that can persist for years (see Figure 6.4). 3. Creating Immunity Vaccination is the introduction of weakened or dead bacteria or viruses, thus creating a specific immunity. Each virus requires such treatment, which makes this process effective for some viruses, such as smallpox, but not for others, such as the variety of viruses that cause the common cold. C. Immune System Disorders Failures of the immune system leave a person open to infection from viruses, bacteria, fungi, and parasites. The immune systems of some children fail to develop, and acquired immune deficiency syndrome (AIDS) destroys the immune systems of adults and children. Allergies are the result of overactive immune systems, and autoimmune diseases result when the immune system fails to distinguish body cells from invaders and starts to attack and destroy body , and D 1. The main function of the immune system is to a. manufacture white blood cells. b. manufacture red blood cells. c. protect internal organs. d. defend against foreign invaders. ANS: d REF: Physiology of the Immune System 2. Leukocytes are a. white blood cells. b. red blood cells. c. platelets. d. capillaries. ANS: a REF: Physiology of the Immune System 3. A function of lymph nodes is to a. secrete thymosin. b. serve as a holding station for red blood cells. c. cleanse lymph of foreign debris. d. all of these. ANS: c REF: Physiology of the Immune System 4. Which of these is NOT an organ of the immune system? a. liver b. spleen c. tonsils d. thymus ANS: a REF: Physiology of the Immune System 5. Which of the following performs specific immune responses? a. phagocytosis b. T-cells and B-cells c. granulocytes d. macrophages ANS: b REF: Physiology of the Immune System