The Immune System and Disease PDF

Chapter 17 THE IMMUNE SYSTEM AND DISEASE: Describe basic animal physiology and homeostasis as maintained by organ systems. THE IMMUNE SYSTEM AND DISEASE 1. Viruses 2. Innate Immunity 3. Adaptive Immunity 4. Disruptions in the Immune System (credit a: modification of work...

Chapter 17 THE IMMUNE SYSTEM AND DISEASE: Describe basic animal physiology and homeostasis as maintained by organ systems. THE IMMUNE SYSTEM AND DISEASE 1. Viruses 2. Innate Immunity 3. Adaptive Immunity 4. Disruptions in the Immune System (credit a: modification of work by James Gathany, CDC; credit b: modification of work by Dr. Fred Murphy; Sylvia Whitfield, CDC; scale-bar data from Matt Russell) This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. VIRUSES Describe how viruses were first discovered and how they are detected Explain the detailed steps of viral replication Describe how vaccines are used in prevention and treatment of viral diseases (credit a: scale-bar data from Matt Russell; credit b: modification of work by USDA, Department of Plant Pathology Archive, North Carolina State University) This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. HOW VIRUSES REPLICATE Viruses can use either DNA or RNA as their genetic material. Genomes are very small, containing only essential genes. Genetic material can be single or double-stranded, linear or circular, and may consist of one or multiple segments. DNA viruses use the host’s machinery and cause chickenpox and herpes. RNA viruses use unique enzymes for and evolve more quickly, causing hepatitis C and measles. Viruses can only infect specific hosts and cells, relying on a viral receptor on the host cell surface to enter and replicate. STEPS OF VIRUS INFECTION A virus must “take over” a cell to replicate. Productive viral infections follow similar steps: 1. Attachment: a virus attaches to a specific receptor on the host cell membrane. 2. Replication: the replication mechanism depends on the viral genome. 3. Assembly 4. Release: some viruses are released when the host cell dies and other can leave the cell by budding. This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. VIRUSES AND DISEASE Viruses are the cause of dozens of ailments in humans, ranging from mild illnesses to serious diseases. (credit: modification of work by Mikael Häggström) This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. VACCINES FOR PREVENTION The primary method for controlling viral diseases is through vaccines. Vaccines can be made using weakened live viruses, killed viruses, or molecular subunits of the virus. Live vaccines are made by attenuation in the laboratory. The polio vaccine was a milestone in the use of vaccines Live vaccines can revert back to their disease-causing state and cause an epidemic! INNATE IMMUNITY Describe the body’s innate physical and chemical defenses Explain the inflammatory response Describe the complement system This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. EXTERNAL AND CHEMICAL BARRIERS The body has physical barriers to potential pathogens: Skin, mucus, hairs Chemical barriers protect against pathogens that get past the physical barriers: The skin and mucus membranes create a chemical environment that’s hostile to microorganisms. The stomach creates a highly acidic environment which kills many pathogens. Beneficial microorganisms outcompete disease-causing organisms. Pathogens still enter the body through abrasions, punctures, or collecting in numbers that overwhelm mucus and/or cilia. INTERNAL DEFENSES When pathogens enter the body, the innate immune system responds with internal defenses: inflammatory response, phagocytosis, natural killer cells, and the complement system When a pathogen is recognized as foreign, cytokines are released. cytokines are chemical messengers that regulate the production of immune responses. Inflammation causes localized redness, swelling, heat, and pain, attracting white blood cells. Neutrophils are the most abundant white blood cells. Macrophages follow neutrophils. ADAPTIVE IMMUNITY Explain adaptive immunity Describe cell-mediated immune response and humoral immune response Describe immune tolerance HUMORAL IMMUNE RESPONSE B-cells respond to antigens by producing antibodies in a humoral immune response. Each B-cell has only one kind of antigen receptor. A helper T cell induces the B cell to divide into: Memory B cells, which remain inactive until another encounter with the antigen. Plasma cells, which produce and secrete antibodies. Active immunity comes from the host’s response to a pathogen. Passive immunity comes from an outside source. This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. IMMUNOLOGICAL MEMORY Response to a pathogen that has not been encountered before is known as primary immune response. A memory cell persists in circulation after an infection is cleared and can mount a secondary immune response. This rapid and dramatic antibody response can stop the infection before the individual realizes they’ve been exposed. This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. IMMUNE TOLERANCE Immune tolerance is the immune system’s acquired ability to prevent unnecessary harmful immune response. It is especially well- developed in the mucosa of the upper digestive system. It allows the immune system to prevent immune responses in undesired tissues and focus on pathogens. DISRUPTIONS TO THE IMMUNE SYSTEM Describe hypersensitivity Describe autoimmunity (credit: modification of work by C. Goldsmith, CDC; scale-bar data from Matt Russell) This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. IMMUNODEFICIENCY Immunodeficiency is a failure, insufficiency, or delay in the response of the immune system. It may be acquired or inherited. It may be acquired as a result of infection, chemical exposure, malnutrition, or extreme stress. Primary immunodeficiencies that are present from birth may also occur. ALLERGIES Allergies result from an immediate response to a usually harmless antigen. On initial exposure, an allergic individual creates antibodies and sensitizes the tissue. Subsequent exposures lead to an allergic reaction caused by the release of histamines and inflammatory chemicals. The effects of an allergic reaction range from mild to life- threatening. (credit: modification of work by NIH) This OpenStax ancillary resource is © Rice University under a CC-BY 4.0 International license; it may be reproduced or modified but must be attributed to OpenStax, Rice University and any changes must be noted. Any images credited to other sources are similarly available for reproduction, but must be attributed to their sources. AUTOIMMUNITY Autoimmunity is a hypersensitivity that results when an antibody marks self-components as foreign. In myasthenia gravis, muscle-cell receptors are targeted by antibodies. In systemic lupus erythematosus, there's a diffuse antibody response to DNA and proteins. Autoimmunity can develop due to molecular mimicry. Infection with the bacteria that causes strep can generate antibodies that react with heart muscle. Insulin-dependent diabetes results from an inflammatory response against the insulin-producing cells of the pancreas.