Pearson's Comprehensive Medical Assisting Administrative and Clinical Competencies THIRD EDITION CHAPTER 28 The Immune System Lesson 1: The Immune System
Lesson Objectives Upon completion of this lesson, students should be able to: 1. Define and spell the terms to learn for this chapter. 2. Identify and discuss the anatomy of the immune system. 3. Discuss the functions of the immune system. 4. Explain the immune system and its response.
Immune System Immune system consists of: Tissues Organs Physiological processes that identify abnormal cells Foreign substances Foreign tissues, such as transplants
Anatomy of the Immune System The Lymphatic System Network of vessels, nodes, ducts more or less parallel, but separate from, blood vessels of the circulatory system Conductive structures are vessels and ducts that help maintain fluid balance by removing excess fluid from spaces between body cells
Anatomy of the Immune System The Lymphatic System Fluid (lymph) comes from blood plasma that has leaked out from capillaries and system collects lymph and returns it to bloodstream
Anatomy of the Immune System The Lymphatic System Lymphoid tissues function as part of immune system helping to defend body against harmful substances Central lymphatic tissue: composed of bone marrow and thymus Peripheral lymphoid tissue: consists of lymphatic pathways, lymph nodes, spleen, and tonsils
Anatomy of the Immune System Bone Marrow Central lymphatic tissue Contains stem cells that develop into all cells of the body in a process called hematopoiesis Immune system cells either become mature cells of immune system or precursors of cells that will mature in a part of body other than bone marrow
Anatomy of the Immune System Thymus Gland Central lymphatic tissue Located posterior to sternum in anterior mediastinum Endocrine gland that secretes substances into bloodstream Divided into two distinct compartments: Outer cortex Internal medulla
Anatomy of the Immune System Thymus Gland Immature lymphoid cells created in bone marrow enter cortex of thymus, reproduce and mature, then move to medulla from which they reenter the circulation of the body Manufactures infection-fighting T cells and helps distinguish normal T cells from those that attack the body's own tissues
FIGURE 28-1 Components of the lymphatic system.
Critical Thinking Questions 1. What is so critical about the immune system to one's overall health? 2. If one has a compromised immune system would that shorten the person's life?
Anatomy of the Immune System The Lymphatic System Peripheral lymphatic tissue Lymphatic pathways: structures that collect and circulate lymph Intricate system of vessels Capillaries Vessels Trunks Ducts
FIGURE 28-2 Structures of the lymphatic pathway from smallest to largest.
Anatomy of the Immune System The Lymphatic System Lymph nodes: many different sizes and shapes; most bean shaped and about 1 inch long covered with thick fibrous capsule Each node has two parts: outer cortex and inner medulla
Anatomy of the Immune System The Lymphatic System Cortex populated mainly with lymphocytes Germinal centers in cortex primary locations where B lymphocytes reproduce
FIGURE 28-3 A cross section of a lymph node.
Anatomy of the Immune System The Lymphatic System B lymphocytes (B cells) responsible for production of antibodies, specialized proteins that lock onto specific antigens Each unique type of B cell produces only one type of antibody Antibody-mediated response or humoral immunity
Anatomy of the Immune System The Lymphatic System Lymph node cortex contains T lymphocytes (T cells) that circulate through lymph nodes, lymphatic ducts, bloodstream to seek out any infection T lymphocytes promote immunity through a cell-mediated response Medulla of lymph node primarily made up of macrophages
Anatomy of the Immune System Spleen Located in upper left quadrant of abdomen Largest lymphatic organ Blood passes through intricate meshwork of tiny blood vessels in spleen and continues on to the liver Spleen's blood vessels lined with macrophages
Anatomy of the Immune System Tonsils Located in depressions of mucous membranes of the throat and pharynx Function is to filter bacteria and aid in formation of white blood cells When tonsils unable to properly filter bacteria and pathogens, they can become enlarged and infected
FIGURE 28-4 Tonsils normal and enlarged.
The Immune System and the Immune system Body's Defenses Body's defense against infectious organisms and pathogenic invaders Immune response Cells, tissues, and organs that make up immune system work together to attack organisms and substances that invade body systems and cause illness and disease
The Immune System and the Body's Defenses Leukocytes, or white blood cells (WBCs), seek out and destroy harmful organisms.
The Immune System and the Two types Lymphocytes Body's Defenses Allow the body to remember and recognize previous invading organisms Phagocytes Attack and ingest (engulf, or eat) the invading organism
The Immune System and the Body's Defenses Antigens Versus Antibodies When an antigen is detected, proteins antibodies/immunoglobulins work together to recognize and respond to it. Terms antibody and immunoglobulin often used interchangeably
The Immune System and the Body's Defenses Antigens Versus Antibodies Immunoglobulins are glycoproteins that function as antibodies Vaccine Fragments of a disease organism or small amounts of weakened disease
The Immune System and the Body's Defenses Antigens Versus Antibodies Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it alone; that is job of T cells Antibodies can neutralize toxins produced by different organisms
The Immune System and the Body's Defenses Antigens Versus Antibodies Antibodies can activate proteins called complement that are part of immune system Complement assists in destroying bacteria, viruses, or infected cells
The Immune System and the Body's Defenses Immunosuppressants and Immunity Immunosuppressants Medications that suppress immune system Usually given after organ transplant to prevent rejection of the organ
The Immune System and the Body's Defenses Immunosuppressants and Immunity Can help prevent organ rejection These medications render patient very vulnerable to illness Extreme stress can also suppress immune system
The Immune System and the Innate Immunity Body's Defenses Everyone born with innate (natural) immunity Passed down from parents to children Provided in part by external barriers of body (skin, mucous membranes, tears)
The Immune System and the Innate Immunity Body's Defenses First line of defense against harmful pathogens Renders many viruses and bacteria that affect other species incapable of harming human beings
The Immune System and the Active Immunity Body's Defenses Unlike innate immunity, is not inborn Develops after birth Permanent and gives individual lifelong protection against the disease Acquired active immunity: person exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response
The Immune System and the Active Immunity Body's Defenses Artificially acquired active immunity: induced by a vaccine, a substance that contains the antigen and stimulates a primary response against the antigen without causing symptoms of the disease
The Immune System and the Passive Immunity Body's Defenses Not permanent form of immunity It only lasts for a little while For example, antibodies passed to an infant through breast milk This temporary form of immunity helps protect infant against infection during early years of childhood
Questions?