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The Immune System Ms. Edwards
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A little history… Before 1900s, surgery was very risky. About 45% of all people who had surgery died. People didn’t know that microorganisms existed. Joseph Lister- 1860s- surgeon who washed his hands before surgery and covered wounds with bandages. Reduced surgery deaths to about 15%.
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A little history… Louis Pasteur- 1860s- boiled beef broth to kill microorganisms. Robert Koch- proved that each sickness is caused by a different microorganism.
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Infectious Disease Pathogen- organism that causes disease
Infectious disease- caused by a living thing in the body (pathogen gets inside body). Pathogens damage individual cells. 4 classes of pathogens: bacteria, viruses, fungi, protists.
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Bacteria Single-celled organisms
Cause ear infections, strep throat, food poisoning, etc. Some bacteria damage cells directly, others release toxins. Toxin- a poison that damages cells. Tetanus (lockjaw) - bacteria get into wound and release toxin that damages nervous system.
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Viruses Much smaller than bacteria.
Viruses aren’t alive! They cannot reproduce unless they are in a living cell. Ex: cold and flu. Not treated with antibiotics.
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Fungi Grow best in dark, warm places. Ex: Athlete’s Foot and Ringworm
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Protists Malaria- blood infection, common in tropical areas, spread by mosquitoes. Amebic Dysentery- spread through contaminated water. African Sleeping Sickness- spread by tsetse flies. Brain infection that causes severe fatigue.
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How Disease Spreads Contact with infected people- hugging, kissing, shaking hands, drinking, sneezing, coughing. Soil, Food, Water- live in soil and spread through unclean food or water. Contaminated Objects- microorganisms live on surfaces (cold and flu spread this way).
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Infected Animals- Animals/insects bite people and spread disease (Lyme Disease from ticks, Malaria from mosquitoes).
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The Body’s Defenses Lines of defense: skin, breathing passages, mouth and stomach. Trap most of the pathogens we come in contact with. Skin- Oil and sweat kill pathogens. They also fall off with dead skin cells. Pathogens can enter skin when it is damaged or cut.
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Breathing Passages- cilia, mucus, and sneezing get rid of pathogens.
Mouth and Stomach- saliva and stomach acid kill pathogens.
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The Inflammatory Response
Inflammatory Response- the body’s second line of defense. Fluid and WBCs leak from vessels into nearby tissues. WBCs fight pathogens. Called the body’s general defense because it is the same regardless of the pathogen.
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WBCs- There are 4 types. Phagocyte- type of WBC that is involved in the inflammatory response. Engulf pathogens. Inflammation- Blood vessels widen and blood flow increases to bring WBCs to injury. Swelling can occur. Fever- helps you fight disease by killing pathogens.
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The Immune System Infection that causes fever triggers body’s 3rd line of defense- the immune response. The immune system can distinguish between different kinds of pathogens. Immune system cells react to each kind of pathogen with a defense targeted specifically at that pathogen.
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Lymphocyte- WBC that distinguishes
Lymphocyte- WBC that distinguishes between different kinds of pathogens. 2 types: T cells and B cells.
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T Cells T cells- Identify pathogens and distinguish one from the other. You have tens of millions of T cells. Each kind of T cell recognizes a different type of pathogen. Antigens- markers on cell surface that identify cell
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B Cells B cells- produce proteins that destroy pathogens (antibodies).
Each B cell produces one kind of antibody. Each antibody has a different structure. Antigens and antibodies fit together like puzzle pieces - their pairing is specific.
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The Immune System - The Body’s Defenses The immune system includes T cells and B cells. The cells work together to fight infections.
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AIDS AIDS- Acquired Immunodeficiency Syndrome
HIV- Human Immunodeficiency Virus- virus that causes AIDS HIV is the only known virus to directly attack and destroy T cells. People can have HIV for several years before they know they have it.
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AIDS More than 40 million people in the world are infected with HIV.
HIV destroys T cells, body’s defenses are weakened. HIV then becomes AIDS. Most people with HIV/AIDS die of common colds or other sicknesses. There is no cure for AIDS.
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AIDS HIV must be inside a living cell to reproduce.
HIV spreads through bodily fluid contact Common causes on infection include sexual contact, needles, blood transfusions (before 1985). NOT spread by touching someone.
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Preventing Disease Active Immunity
Immunity- body’s ability to destroy pathogens before they can cause disease. 2 types of immunity- active and passive. Active Immunity Body produces antibodies to fight pathogens. A person acquires active immunity when their own immune system produces antibodies in response to the presence of a pathogen.
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Active Immunity Immune Response- some T and B cells keep a “memory” of the pathogen. If that pathogen enters the body again, memory cells recognize antigen. Memory cells quickly start immune response so you don’t get sick. Active immunity protects you for several years or a whole lifetime.
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Active Immunity Vaccination- Antigens of virus are purposely introduced into the body. Vaccine- substance used in a vaccination. Consists of weakened or killed virus. You usually don’t get sick, but you get a memory of the virus.
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Active Immunity - Preventing Infectious Disease A person acquires active immunity when his or her own immune system produces antibodies in response to the presence of a pathogen.
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When You Get Sick Antibiotics- chemical that kills bacteria or slows their growth Antibiotics do not work on viruses! For a speedy recovery, eat well, drink plenty of fluids, and get lots of sleep.
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Passive Immunity Results when antibodies (instead of antigens) are given to a person. Lasts only a few months. Babies get passive immunity from mom.
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Comparing and Contrasting
Passive Immunity Active Immunity Antibodies are given; the body does not make antibodies. The body makes antibodies. Can prevent diseases Immunity can be acquired from the mother during pregnancy. Memory cells recognize antigens. May involve an injection Immunity may last for years or a lifetime. Immunity lasts only a few months.
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Noninfectious Disease
Diseases that aren’t caused by pathogens. Have become more common than infectious diseases. Can’t be passed from person to person. Cardiovascular Disease- leading cause of death in America.
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Noninfectious Disease- Allergies
Allergies- immune system is overly sensitive to a foreign substance that isn’t harmful to the body. Allergen- substance that causes allergy (pollen, dust, mold, foods, medicines, pets). Histamine- chemical that causes allergy symptoms. To reduce allergies, avoid allergens!
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Noninfectious Disease
Asthma- a condition in which the respiratory passages narrow significantly. Causes shortness of breath.
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Noninfectious Disease- Diabetes
Diabetes- a condition where the pancreas does not produce insulin, or the body’s cells do not use it properly. Insulin- allows body cells to take in glucose and use it for energy. A person with diabetes has high levels of blood glucose, but their body cells do not have enough glucose.
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Noninfectious Disease- Diabetes
Diabetes symptoms: weight loss, weakness, extreme hunger, excessive thirst, frequent urination, blindness, kidney failure, heart disease. Type 1 Diabetes- begins in childhood, pancreas produces little insulin. Type 2 Diabetes- develops during adulthood, can control symptoms by diet, weight control, and exercise.
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Noninfectious Disease- Cancer
Cancer- disease where body cells divide uncontrollably and destroy healthy tissue in the process. Unchecked cells form tumors (mitosis) which feed off blood supply to body parts, and can spread throughout body. Not all tumors are cancerous.
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Noninfectious Disease- Cancer
Causes of cancer- genetics, carcinogens, diet, lifestyle. Carcinogens- environmental factors that cause cancer. Treatment- surgery, drugs, radiation (high energy waves that kill cancer). To prevent cancer, avoid carcinogens.
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