Immune System and Disease Chapter 31 Sections 1-4, 6

Pathogens and Human Illness What are some causes of diseases? We can have infectious and noninfectious diseases. Infectious can be passed from one person to another because of germs. What are some examples? Noninfectious diseases can’t be passed on. They result from a person’s genetics or lifestyle. What are examples of this?

Pathogens and Human Illness 1850s French scientist Louis Pasteur makes the connection that microorganisms can cause disease, which is the Germ Theory. The disease causing microorganisms are called Pathogens. No pathogens = no illness Not everyone thought this was true at the time. 1861-1865 Joseph Lister has half of his patients die from infection after successful surgeries. Learns of Pasteur’s Germ Theory and starts using a weak acid to clean his instruments and surgical sites dropping the number of patient deaths near zero.

Pathogens and Human Illness German scientist Robert Koch did experiments that proved that 4 conditions needed to be met before someone could say that a certain pathogen caused a disease: 1: The pathogen has to be present in every case 2: The pathogen must be isolated and grown outside the body in a pure, uncontaminated culture. 3: Healthy animals infected with the pure culture must develop the disease. 4: The pathogen must be re-isolated and cultured from the newly sick animals and must be identical to the original pathogen.

Pathogens and Human Illness We have 5 major groups of pathogens: Bacteria Viruses Fungi Protozoa Parasites

Pathogens and Human Illness Bacteria: single-celled organisms. Cause illness by releasing chemicals that are toxic to the host (us) Can destroy healthy body cells Food poisoning is an illness caused by bacteria.

Pathogens and Human Illness Viruses: disease causing strands of DNA or RNA that are surrounded by protein coats. Enter and take over a healthy cell and makes it produce more viruses

Pathogens and Human Illness Fungi: multicellular or single-celled Disease causing pierce through healthy cells and take the cell’s nutrients. Usually occur in places that are warm and damp.

Pathogens and Human Illness Protozoa: single-celled organisms that prey on other cells. Need healthy cells to complete their life cycles.

Pathogens and Human Illness Parasites: organisms that grow and feed on a host. Some can kill the host, other’s will drain the body’s resources without killing the host

Pathogens and Human Illness These things invade our bodies in many different ways. Needs to be by direct or indirect contact. Direct contact means that one person has to be infected and then touch the other person either directly or by other things (HIV, STDs, Bites, shared needles) Indirect contact is when the pathogen survives on nonliving surfaces like tables and door knobs.

Pathogens and Human Illness Sometimes these things live in the soil and enter our body by piercing through our bare feet. Some travel around in the air, especially when we sneeze. Sometimes they get in by using a vector, anything that carries and transmits a pathogen into healthy cells. Malaria is spread by a mosquito. Bubonic Plague (Black Death) spread by rat fleas. Food can also let them in

Immune System The Immune System is the body system that fights off infection and pathogens. Relies on physical barriers to keep things out. Skin is the first line of defense. Produces oil and sweat which many pathogens can’t survive that kind of environment Around your eyes, nose, ears, and mouth we have mucous membranes that make sticky liquid to trap pathogens.

Immune System Once the pathogens get inside our White Blood Cells act as the body’s military. They find and kill pathogens that enter the body. Basophils and Mast cells release chemical signals to attract more white blood cells. If it’s a parasite that invades eosinophils come and spray the parasite with poison. If it’s a virus, bacteria, or fungus the neutrophils and macrophages attack. These are called phagocytes. Phagocytes surround and engulf pathogens, killing them.

Immune System After those, lymphocytes get to the infection. These are white blood cells that start the specific immune responses. We have 2 types: T cells: destroy body cells that are infected with pathogens B cells: Make proteins that inactivate the pathogens that have not yet infected the body cells.

Immune System Our body uses 3 kinds of proteins to fight off pathogens. Complement proteins are made by white blood cells and some organs. Weaken a pathogen’s cell membrane letting water get in and have them burst Send phagocytes to the pathogen Antibodies are made by B cells. Destroys pathogens in 3 ways: They bind to the pathogen membrane making them not work. They make the pathogens clump together to signal phagocytes to attack. They can activate the complement proteins.

Immune System Interferons are proteins made by body cells that are infected by a virus. They tell uninfected body cells to make enzymes that will keep viruses from getting inside of them. They can also start an inflammation response.

Immune System Normally once we are infected with something our body remembers what it is so we can fight it off again if it comes back so we won’t get sick. We become immune. There are 2 types of immunity: Passive immunity: immunity that occurs without our body having to go through an immune response. Mother passes immunity to baby Genetics keeps certain pathogens from infecting certain species Active Immunity: immunity that our body produces after we go through an immune response.

Immune Responses In the last section we covered specific immune responses. Nonspecific immune responses are the ones that happen in the same way to every pathogen. Two kinds of nonspecific responses: Inflammation Fever

Immune Responses Inflammation is characterized by swelling, redness, pain, itching, and increased warmth at the affected site. When a pathogen enters the body or when the body’s other tissues are damaged, inflammation starts. Example: Scraping you knee Mast cells and Basophils signal the body to make histamine in response to a pathogen invasion. Histamine lets the cells in blood vessels spread out. Fluids rush in and out of the vessels and into surrounding tissue. White Blood Cells can move in and out and start the fight. When they finish inflammation stops.

Immune Responses

Immune Responses Fevers start when Mast cells and macrophages tell the hypothalamus to raise the body temperature. When the infection is controlled the mast cells and macrophages stop producing chemicals and the temperature goes back to normal. A fever of about 100 degrees stimulates the production of interferons white blood cells which help fight the infection. When a fever gets too high (103 degrees) the hypothalamus loses control of body temperature. Enzymes in the body stop working and chemical reactions stop. High fevers can lead to seizures, brain damage, and death

Immune Responses With a specific immune response we have cells that let us know which ones are healthy and belong to us and which ones are pathogens. Antigens are protein markers on the surface of cells and viruses that help the immune system identify a foreign cell or virus. We have 2 kinds of specific immune responses that will lead to acquired immunity. Memory cells are special T and B cells that provide acquired immunity because they remember the antigens that have been fought off by our bodies.

Immune Responses Cellular Immunity is an immune response that depends on T cells. T cells attach to infected body cells and make them burst. A phagocyte recognizes a foreign invader and eats it and then takes the pathogens antigens and shows them off (antigen-presenting cell). A T cell finds this cell and binds to it. Activates the T cell. The T cell divides and become activated T cells and Memory T cells. Activated will fight and memory will wait for future invasions. Activated T cells will bind to and destroy infected cells.

Immune Responses Humoral Immunity is a type of immune response that depends on antibodies. A pathogen binds to a B cell. The B cell eats the pathogen and puts it’s antigens on to the surface. T cells find and bind to the B cell and activate the B cell. The B cells divide into activated and memory B cells. Activated B cells produce as many as 2000 pathogen- specific antibodies per second. Causes pathogens to clump. Phagocytes eat and destroy the pathogen clumps. Tissue rejection occurs when the recipient’s immune system makes antibodies against the protein markers on the donor’s tissue.

Immunity and Technology To prevent infections, clean your environment. This INCLUDES your HANDS. Heat and chemicals kill pathogens that are outside of our body. Antiseptics are chemicals, like soap, vinegar, and rubbing alcohol, that kill pathogens. When pathogens make it inside we can use medicines to try and kill them. Antibiotics target bacteria and fungi and keep them from growing and reproducing. Antibiotic Resistance

Immunity and Technology Antibiotics are for bacteria and fungi Vaccines are used to PREVENT infection. Being vaccinated allows your body to develop acquired immunity without actually getting the disease. Vaccine is a substance that contains the antigen of a pathogen. The antigens are weakened so they can’t make you sick. 4 types of vaccines: Contain whole dead bacteria or viruses Live attenuated vaccines have weak living pathogens Component vaccines use only the parts that have the antigens Toxoid vaccines are made from inactivated bacterial toxins

Diseases that Weaken the Immune System Red bone marrow makes red and white blood cells and platelets. When mature red blood cells die, new ones replace them. Leukemia is cancer of the bone marrow. It doesn’t form tumors. It prevents bone marrow from functioning properly. One type of leukemia produces white blood cells that don’t mature properly. Since they’re not mature they can’t fight infections. The bone marrow tries to replace them and forgets to make new red blood cells and platlets.

Diseases that Weaken the Immune System To cure this a bone marrow transplant has to be done. Sometimes the donor marrow makes antibodies against the host. The large amounts of radiation and chemotherapy can weaken the immune system and allow for opportunistic infections. Opportunistic infections are infections caused by a pathogen that a healthy immune system would normally be able to fight off.

Diseases that Weaken the Immune System More than 40 million people in the world have HIV/AIDS. In the 1980s fewer than 2 million people had it. Human immunodeficiency virus (HIV) is a retrovirus that attacks and weakens the immune system . People normally don’t die from the actual virus but from the opportunistic infections they get.

Diseases that Weaken the Immune System

Diseases that Weaken the Immune System HIV can only live in human blood cells and so it won’t survive for long outside of the body. You CANNOT get HIV/AIDS from shaking someone’s hand or swimming in the same pool. HIV infects the T cells and makes them ineffective and it makes more HIV. A single T cell can make thousands of HIV viruses before it dies. As it reproduces the body can’t make healthy T cells fast enough. People can contract HIV and never notice for 10 or more years.

Diseases that Weaken the Immune System Acquired immune deficiency syndrome (AIDS) is the final stage of the immune system’s decline due to HIV. HIV is a virus, AIDS is the condition of having a worn out immune system. People with AIDS get a lot of different opportunistic infections. AIDS always results in death because their body can’t fight anything off. There is NO CURE. Treatment just slows it down and is very expensive.