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Transcript
What is a system? • A group of tissues (organs) that work together to do a certain task. • Ex) digestive system, circulatory system, immune system… • Function of the immune system is to protect your body from invasion of pathogens. “The War on Pathogens” • Your body is always surrounded by pathogens. • Pathogen is ?. • Viruses, bacteria, fungi, etc. • Germ theory—infectious diseases are caused by microorganisms of different types. • Diseases can be passed from one person to the next are called infectious or communicable. Non-Specific Defense • Your body has several defense mechanisms to keep them out….. FIRST LINE OF NON-SPECIFIC DEFENSE 1) skin 2) sweat 3) mucous membranes 4) saliva SECOND LINE OF NON-SPECIFIC DEFENSE • inflammatory response First Line: Skin • Physical barrier • Chemical barriersecretes oil, sweat, and tears • Sheds constantly (1 million cells per hour) First Line: Mucus Membranes • These line the inside of all body openings. • Nostrils, mouth, lungs, etc. • Cells of mucus membranes: – secrete mucus that traps foreign objects – lined with hairs called cilia. • Stomach also has acid Second Line of Defense: Inflammatory Response • The first line of defense has been broken… • SECOND LINE OF DEFENSE ACTIVATED: damaged cells release chemical messages that trigger a series of reactions by body-histamine 1.) capillaries to swellpuffiness 2.) increases blood flow to infected area redness 3.) temperature in area rises 4.) pain 5.) phagocytes called inget rid of pathogens ***Sometimes this response is NOT enough… Immune System Non-specific Defense Immune System leave room to add more here First line: Skin Sweat Mucous Stomach acid Second line: Inflammatory Response and Phagocytes What if pathogens circulate through your body? • White blood cells have to take over. • White blood cells = “soldiers” of your immune system. The Immune Response Specific Defense • Body’s attack against a pathogen that made it past the “front lines.” • Results in “immunity” because your immune response creates memory cells SPECIFIC for each pathogen. • Chicken pox SPECIFIC IMMUNE RESPONSE SECOND LINE OF DEFENSE: INFLAMMATORY RESPONSE NON-SPECIFIC FIRST LINE OF DEFENSE: SKIN, MUCOUS, SWEAT Organs of the Immune System White blood cells are called leukocytes Made in the thymus (T cells) and bone marrow (B cells) Stored in tonsils, spleen, and lymph nodes. “The Soldiers” White Blood Cells • Leukocytes – – – – – – Macrophages Helper T cells Killer T cells B cells Suppressor T cells Memory cells How does your body know there is an invader? • All pathogens have “distinct” marker proteins that are antigens. • Antigens -anything that causes an immune response. • Your body must recognize antigens as FOREIGN (NON-SELF) in order to create an immune response. Step #1 “Invader Identification” Movie • Macrophages identify pathogen as “non-self,” eat it, display the antigen, and signal for helper T cells. • Interleukin-1 signal released= fever • Helper T cells “signal” for the production of other leukocytes by releasing of interleukin 2. • The next type of leukocytes called to work are known as B cells and Killer T cells. Step #2 “Cloning Phase” • Many helper T cells, B cells and killer T cells produced. • After B cells called up by helper T’s, they begin to produce lots of antibodies What are antibodies? • Millions of antibodies are made by B cells • They are like “keys” and are specific to each antigen which are like the “locks.” • Mark pathogen for death and can also prevent virus attachment to cell. Step #3 “The Attack Phase” • Pathogens marked with antibodies are destroyed by macrophages. • Killer T cells destroy any infected body cell. Movie Step #4 “Memory Phase” • Macrophages act as the clean up crew, eating pathogens, damaged body cells, etc. • Suppressor T cells “call off the troops”. They suppress, or weaken, the attack. • Powerful memory T and B cells are left behind to “remember” the attack and quickly recognize a pathogen if it re-enters the body. Primary vs. secondary immune response – Primary: – 1st time in contact with pathogen. – Takes longer for attack – Secondary: – come into contact with a pathogen you’ve already encountered – memory B cells are there to produce antibodies quickly and in greater amounts. Primary response Secondary response Immune System Non-specific Defense First line: Skin Sweat Mucous Stomach acid Immune System Second line: Inflammatory Response and Phagocytes B cells: Antibodies and Memory Cells Specific Defense= Immune Response Reaction to specific antigen Macrophage signal Helper T cells signal Killer T cells Active vs. Passive Immunity • Active Immunity (immune response, vaccine) – The body ACTIVELY produces its own antibodies • Passive Immunity (breast milk) – Get antibodies from mother’s milk. Immune System Failure Allergies • Allergy: Immune system response against a NONPATHOGENIC antigen. • Food, pollen, bee stings, dust mites Immune System Failure Allergies • Body produces more antibodies than you need, which causes release of histamine: – blood vessel dilation – swelling • Antihistamines are in allergy medicine that reduce swelling. • Asthma • Movie Immune System Failure Autoimmune disease Immune system fails to distinguish self from non-self. Body makes antibodies against and attacks own cells. Examples: MS (attack nerve cells) Lupus (attacks organs) Rheumatoid arthritis (attacks joints) Immune System Failure Cancer • One major job of the immune system is immunological surveillance. • Killer T cells destroy our cancerous cells. • Immune system fails to locate and remove cancerous cell, & it multiplies to form a tumor. • Malignant tumor spreads, benign does not AIDS Acquired Immunodeficiency Syndrome • Sometimes the immune system collapses totally. • HIV (Human Immunodeficiency Virus) invades helper T cells • B cells and killer T cells not stimulated to work—immune system breaks down! • Body overwhelmed with pathogens Immune System Non-specific Defense First line: Skin Sweat Mucous Stomach acid Immune System Second line: Inflammatory Response and Phagocytes B cells: Antibodies and Memory Cells Specific Defense= Immune Response Reaction to specific antigen Macrophage signal Helper T cells HIV signal Killer T cells Immune System Failures Overreact: Allergies Asthma Can’t tell self from non self: Autoimmune disease Immune system shut down due to HIV: Immunodeficiency (AIDS) Immunological surveillance doesn’t locate bad cells: Cancer Blood types • Each red blood cell has protein markers • A type blood---A protein markers • A person with type A blood makes antibodies against B markers because they are foreign • The B markers are considered antigens to the person with A blood Blood types Blood types • Universal donor: type O because no protein markers to cause immune response. • Universal recipient: type AB because they have both A and B markers and so don’t make antibodies to either.