Immune System Crash Course Malcolm, Max, Brycen

Basic Info The immune system is a network of cells, tissues, and organs that work together to defend the body against attacks by “foreign” invaders. 1. Nonspecific Innate Defense 2. Adaptative Immunity 3. Immunological memory

Step 1. Nonspecific Innate Defense 2nd Line of Defense These are the preventive measures used when a pathogen successfully enters the body and nonspecific cells attack the pathogen. Goal: Limit the spread of the pathogen prior to the advance of the specific immune response. Examples: Histamine: increases blood flow to an infected area to bring key nonspecific cells to attack the pathogen. Basophils and Mast cells in the connective tissue secrete histamine. Prostaglandins also promote vasodilation. 1st Line of Defense This is the initial barrier and first preventive measures to prevent pathogens from entering the body. Examples: Skin-(ph level makes it difficult for microorganisms to live on) Mucous membranes- release mucus that has antimicrobial substances and lysozyme Cilia- located in the respiratory system; push the mucus containing the microbes. Stomach acid Hey Bud

Examples of Second Line Defense(con’t) Pyrogens: Increase the body temperature to help speed up the immune system response. Also the increased body temperature makes it difficult for microbes to function normally. Complement: a group of proteins that break down the pathogens Interferons: Help prevent the viruses from replicating. Natural Killer Cells: These cells destroy the virus-infected cells by attacking their cell membrane and causing it to lysis PHAGOCYTES: Eating cells, these cells engulf invading pathogens Phagocytes are either neutrophils and macrophages Neutrophils: engulf the pathogen and then die shortly after Macrophages form from monocytes and have the ability to engulf several microbes over a long period of time. These two Phagocytes use a mixture of lysozyme and two toxic forms of oxygen to break down the pathogen. Superoxide anion and nitric oxide

Step 3. Adaptive Immunity Antigens: is any substance that causes an immune response from B or T cells Epitopes: is an accessible part of an antigen that promotes a immune response from a B or T cell. APC: Antigen presenting cell, these cells present a antigen or a part of an antigen(epitope). Some examples is a Dendrite, macrophage Effector cells: Are the cells that are active and attack the pathogen while the pathogen is in the body These cells dont live very long. Memory cells: Are the cells stay in the body for the rest of a person’s life and can quickly respond to future exposure to the same antigen This is the third line of defense that involves B and T lymphocytes. There are three stages of Adaptive Immunity: Recognition: B and T lymphocytes have to recognize specific antigens or epitopes by binding to them. However, in order for these cells to recognize an antigen, it must be displayed by an antigen-presenting cell(APC). Activation Phase: when the B and T cells bind to the Antigen, which causes them to go undergo cell division rapidly to form effector cells and memory cells

Step 3. Adaptive Immunity 3. Effector Phase: After the B cells are activated they go through the Humoral Response and when the T cells are activated they go through the Cell-mediated Response. Humoral Response: This is when active B cells called plasma cells produce antibodies also known as immunoglobulins. Cell-mediated Response: Is the process where a Cytotoxic T cell attacks and kills infected cells by releasing perforin and granzymes.

TWO VERY IMPORTANT TERMS!!!! T Cells: Fight pathogens through the cell-mediated response. Arise from stem cells in bone marrow but mature in the Thymus and circulate in the Lymphatic system Two types: Helper and Cytotoxic T cell Helper T cell: Helper T cell is activated by interacting with an APC. When the Helper T cell is activated they release cytokines, and two type of interleukin to trigger the cell mediated response and the humoral response. Cytotoxic T Cell: These cells attack and kill infected body cells by releasing perforin and granzymes causing the infected cell to lysis. B cells: Fight pathogens through the humoral response. Arise from stem cells in bone marrow and mature there and circulate in the Lymphatic system Once the B cell is activated they undergo multiple divisions and produce clones that become effector cells called plasma cells These produce antibodies.

Two types of Immunity Passive Immunity: This form is temporary This is when Antibodies are transferred to an person that was from someone else Ex: Is when a baby receives antibodies from the mother through the placenta Active Immunity: This form is permanent This when a person recovered from an illness and now has the antibodies to fight that illness again. Or….. If one obtains a vaccine for an illness. Vaccine: is a type of medicine that contains a dead or weakened version of a virus. Used to prevent illnesses caused by viruses. CANNOT CAUSE AUSTISM

Important Terms Antibodies- A group of globular proteins that destroy antigens. They are secreted by plasma cells(activated B cells). Clonal Selection: is the when one lymphocyte matches a specific antigen or epitope and triggers the activation of the lymphocyte Major Histocompatibility Complex: Also known as MHC is the marker on cells to identify cells as self. Two types class I and class II Class I MHC: is found on every body cell with a nucleus. Class II MHC: is found on specific cells such as the macrophages, B Cells, dendritic cells and activated T cells.

Important Terms Immunological Memory: Is the ability for memory B and T cells to rapidly react to any future encounter with same antigen.

Plants Immune System Think About it….. Plants do not have the ability to run away from their predators, so they certain defenses from herbivores and pathogens.

Plants Immune System Systemic Acquired Response Hypersensitivity Response Once a virulent pathogen attaches to the R protein on the cell wall a transduction pathway is activated. Seals of the infected area and causes a production of hydrogen peroxide that kills the infected cells and the surrounding cells. Before the infected cells die they signal to the rest of the plant there is a pathogen in the plant. Using methylsalicylic acid Systemic Acquired Response The methylsalicylic acid is converted to Salicylic acid. The salicylic acid that induces the production of pathogen-related proteins(PR proteins) PR proteins: This protein will protect the entire plant from the pathogen for a couple of days, but is not permanent.