Chapter 14 Lecture Notes PDF

Chapter 14: Infectious Disease and the Immune System How Are Invaders Repelled, Evaded, or Killed? From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Chapter 14: Infectious Disease and the Immune System How Ar...

Chapter 14: Infectious Disease and the Immune System How Are Invaders Repelled, Evaded, or Killed? From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Chapter 14: Infectious Disease and the Immune System How Are Invaders Repelled, Evaded, or Killed? From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Learning Objectives 14.1 Describe the history and biology of cholera. 14.2 Describe the array of potential pathogens humans are exposed to every day. 14.3 Explain how the human immune system works, and predict the effect of the removal of a portion of the system. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Learning Objectives, Part II 14.4 Assess the strengths and weaknesses of natural immunity, vaccination, and passive immunity. 14.5 Assess the use and describe the production of antivenom, antibodies, and antibiotics. 14.6 Predict the impact of personal choices on your health and the health of those in your community. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Case Study The Summer of Sorrow Irish farmers had one crop: potatoes. When a new fungus emerged in the 1840s, it devastated their crops. A flood of Irish immigrants came to the U.S. to escape this famine. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Case Study The Summer of Sorrow, Part II These immigrants were blamed for the spread of cholera, a serious intestinal infection that was often fatal. They were quarantined on a small island where the death toll became staggering. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  What Causes Cholera? People who get cholera can become dehydrated from diarrhea and die within 24 hours. One of the biggest fears was that no one knew how it spread or what caused it. Two people sought to answer those questions. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  What Causes Cholera? Part II During an outbreak in London in 1854, John Snow traced the paths by which cholera spread. He traced it to a water pump. Sewage had leaked into the water from this pump. When the pump handle was removed, the outbreak stopped. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  What Causes Cholera? Part III Robert Koch wanted to know what was in the water that caused cholera. He examined the feces of cholera patients microscopically and discovered a bacterium, Vibrio cholerae. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  How Cholera Affects the Body Patients lost not only a significant amount of water but also lost electrolytes, electrically charged substances necessary for muscle function. Losing both sent patients into shock, the body’s response to an inadequate supply of blood for circulation. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  How Cholera Affects the Body The intestines become filled with fluid, some of which comes from the circulatory system. This leads to a drop in blood pressure and an accelerated heart rate as the heart tries to deliver oxygen to the body. Patients suffer multiple organ failure. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  How Vibrio Bacteria Survive and Spread Cholera The Vibrio bacteria are pathogenic – they cause disease. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press How Vibrio Bacteria Survive and Spread Cholera, Part II Vibrio, once ingested, has to get by the acidic environment in the stomach. They do this by sheer numbers. Once in the small intestine, they attach to cells and secrete a toxin, or poison. Part of the toxin enters the cell and interferes with the pathway that controls water balance. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press How Vibrio Bacteria Survive and Spread Cholera, Part III From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press How Vibrio Bacteria Survive and Spread Cholera, Part IV The cholera toxin will bind to a G protein, permanently switching it to the “on” position. This causes chlorine and sodium to rush into the intestines. Where these ions go, water goes. Water rushing into the intestine causes diarrhea, which is needed to deliver Vibrio to their next host. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.2 What Invaders Do We Face? We are surrounded by various types of microorganisms. Some of them are prokaryotic (no membrane-bound organelles). These prokaryotic organisms can help us (digest food) or hurt us (cholera, tuberculosis, cholera). From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.2 What Invaders Do We Face? Part II Other microorganisms are protozoans, single-celled eukaryotic organisms. Examples include giardiasis, amoebic dysentery, and malaria. Multicellular eukaryotic examples include fungi that cause yeast infections, athlete’s foot, and ringworm. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.2 What Invaders Do We Face? Part III Viruses and prions are other pathogens, but these are not even alive. Viruses have to replicate inside their host’s cell. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.2 What Invaders Do We Face? Part IV Prions are self-replicating proteins. Some prions are normally found in the brain. Can be transformed into pathogens that can cause mad cow disease, Creutzfeldt-Jakob disease. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? First line of defense: – Stops the pathogens from getting in – Mechanical and chemical barriers are nonspecific barriers - they are not designed to stop one particular type of pathogen. – Skin and mucous membranes are types of nonspecific barriers. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? Part II Insert table 14.1 From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? Part III Second line of defense Stops the pathogens from residing in our bodies. These are nonspecific and fall in three categories: – Defensive cells: Macrophages “eat” microbes, and natural killer cells kill virus-invaded cells by penetrating their membranes and causing the infected cell to burst. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.3 How Does the Immune System Protect Us? Part IV – Defensive proteins: Interferons fight viruses and complement proteins coat bacteria, making them easier for macrophages to eat them. – Inflammatory response: the red, warm, and painful swelling is called inflammation. This response brings members of the immune system to the damaged area. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.3 How Does the Immune System Protect Us? Part V From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? Part VI Third line of defense: Two types of specific immune responses: antibody-mediated and cell-mediated. Antibody-mediated responses are achieved mainly through the action of B lymphocytes, or B cells. B cells have a receptor on their membrane that recognizes foreign molecules, or antigens. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.3 How Does the Immune System Protect Us? Part VII From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? Part VIII Once a B cell has its receptor bind to and recognize an antigen, it does two things: – It produces more and more of these receptors (antibodies) and secretes them. – It creates a population of memory cells, cells that do not produce antibodies but remain in the body for years. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? Part IX Cell-mediated immunity: Involves a different type of white blood cell, the T cell There are two types of T cells: cytotoxic T cells and helper T cells. Cytotoxic T cells specialize in killing infected cells or pathogens. Helper T cells help in this process and coordinate the activity of the immune system. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.3 How Does the Immune System Protect Us? Part X From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.3 How Does the Immune System Protect Us? Part XI When the immune system fails: Sometimes B and T cells attack our own cells, leading to an autoimmune disease like rheumatoid arthritis, multiple sclerosis, lupus, or type 1 diabetes. Sometimes B and T cells are weak and don’t launch a strong attack, as seen in immunosuppressive diseases like AIDS. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  How Do We Know? The Immune Response Is Two- Fisted Bruce Glick was studying the function of the bursa of Fabricius (BF) in chickens by removing it and observing what happened. His friend Timothy Chang was studying immune response of chickens and borrowed some of Glick’s chickens. They discovered two components to a immune response, a cell-mediated one and an antibody-mediated one. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  How Do We Know? The Immune Response Is Two- Fisted, Part II From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Life Application Organ and Tissue Transplantation Patients receiving organs have a bigger issue than the surgery itself. Immune system is designed to attack anything it perceives as foreign. Unless the organ came from the same person or an identical twin, the cytotoxic T cells will attack it. This is why donors are “matched” and recipients take immunosuppressive drugs. Currently, not enough organs are available, but regenerative medicine is working to correct that problem. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Life Application: Organ and Tissue Transplantation, Part II From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.4 How Can We Harness the Immune System? Natural immunity: immunity that occurs as a result of having recovered from a previous bout with an infectious disease. Vaccination: a weakened form of a pathogen that can be injected or taken orally; it is similar enough to the actual pathogen that memory cells produced by the immune response will recognize and disable the real pathogen if a person is exposed later. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.4 How Can We Harness the Immune System? Part II From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.4 How Can We Harness the Immune System? Part III Passive immunity: the temporary transfer of antibodies from one individual to another; for example, the antibodies that circulate in a mother’s blood can cross the placenta and enter the fetal bloodstream. Breast milk also has antibodies that help the baby. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.5 What Can Help If Our Immune System Fails? Antivenom: antibodies given by injection that can disable snake venom. – Made by injecting goats or horses with increasing amounts of snake venom. – They make antibodies that can be isolated. – This is a temporary form of immunity. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.5 What Can Help If Our Immune System Fails? Part II Antibodies: antibodies can be isolated from one person and given to another to help boost immunity. This can also be achieved via monoclonal antibodies (Mabs), which target only diseased cells. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Technology Connection Monoclonal Antibodies: Magic Bullets? Scientists recognized the problem of B cells having a finite life span, and sought to make selected B cells immortal. They collected B cells for a type of antigen and fused it with a cancer cell. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Technology Connection Monoclonal Antibodies: Magic Bullets? Part II These hybrids produce one type of antibody and are immortal. The antibodies produced are called monoclonal antibodies (MAbs). Mabs are being used to treat a whole host of diseases like leukemia, breast cancer, lymphoma, etc. Currently, researchers are working to make the MAbs fully human, eliminating some of the side effects caused by their source (mice). From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.5 What Can Help If Our Immune System Fails? Part III Antibiotics: the chemicals that microorganisms produce to kill or inhibit other organisms. – Overuse has created bacteria that are resistant to multiple types of antibiotics. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press 14.6 How Can We Prevent the Spread of Infectious Disease? Wellness: disease spreads more easily through a weakened population. Hygiene: practicing good hygiene can prevent the spread of the disease, even during an outbreak. Clean water and sewers: when human waste doesn’t have the chance to seep into drinking water, cholera and other types of infectious diseases disappear. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  14.6 How Can We Prevent the Spread of Infectious Disease? Proper antibiotic use: Part II improper use of antibiotics can actually help a disease spread. Vaccines: it is important that everyone gets vaccinated, not just an individual. If everyone is vaccinated, the reservoir for the pathogen is eliminated. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press  Scientist Spotlight: Anthony S. Fauci He was the point person for the fight against HIV/AIDS. When demonstrators stormed the campus where he worked, he invited the leaders to come in and talk. This led to the participation of activists in many phases of planning and the development of new models for testing treatments. Dr. Fauci made differences not only as a leader but as a scientist, too. From Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press