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The Immune System Health and Disease Disease is an abnormal condition that affects the body of an organism. Germ Theory of Disease: Observations of Louis Pasteur and Robert Koch led them to believe that infectious diseases were caused by microorganisms of different types (germs). Science that deals with protecting and improving the health of the people in a community • Focuses on the health of the whole population • Ways to improve public health: • Education about diseases and causes Provide clean drinking water Promote healthy living habits Ex. Farmers markets and hand sanitizers in schools and hospitals Research causes and treatments of various diseases Vaccination Campaigns Food and Drug Safety regulations Types of Diseases Infectious Disease Spread from one organism to another Measles and the common cold Pathogens Organisms and agents that cause infectious diseases Certain bacteria, fungi, protists, and viruses Noninfectious Disease Does NOT spread from one organism to another Cancer, diabetes, allergies, heart disease, and most mental illnesses Causes can include: environmental factors such as chemicals and radiation, individual’s genes, behavior such as smoking, poor eating habits, lack of physical activity, etc. • Spread from one organism to another • Agents of Disease: Bacteria: living, break down the tissues of an infected organism for food, or release toxins that interfere with normal activity in the host Streptococcus, anthrax, pneumonia, lime disease Virus: nonliving, replicate by inserting their genetic material into a host cell and taking over many of the host cell’s function. Common cold, influenza, chicken pox, rabies Fungi: cause infections on the surface of the skin, mouth, throat, fingernails, and toenails Ringworm, thrush Protists: single-celled eukaryotes may infect people through contaminated water and insect bites Malaria, African sleeping sickness Parasites: worm-like (that infect humans), may enter through mouth, nose, skin, etc. Trichinosis, hookworm • NOT spread from one organism to another • Genetic • • passed down from one generation to another to its offspring Not always “ALL-OR-NOTHING” • You may get the gene but outside factors can influence the expression of disease Ex: Gene for heart disease influenced by diet and exercise • Mutations • changes to an organism’s DNA • Changes in an organisms DNA • A mutation is passed down to every cell that develops from that mutated cell • If a REPRODUCTIVE CELL or GAMETE mutates mutation can be passed from parent to offspring • If SOMATIC or NORMAL cell mutates mutation CANNOT be passed to offspring • Environmental factors • Radiation • Toxins/chemicals • Natural (plants animals and fungi) • Unnatural (pollution) • Air Pollution •Respiratory disease (asthma) and lung cancer • Water and Soil Pollution • Heavy metals taken in by plants and eaten by us • Heavy metals runoff into lakes and rivers and get into our water supply • Poor habits • Drugs • Alcohol • Tobacco Bacteria and disease Reproduce rapidly Spread easily Break down cells in the host’s body for food=tissue damage Release toxins into hosts’ body Toxin- a poison that acts on a particular body system Ex. Bacteria that causes strep throat releases toxin that can cause scarlet fever Tetnus-disease caused by bacteria that also release toxin that affects nervous system Diseases caused by bacteria Strep throat Pneumonia Anthrax Lyme disease Viral Infections • What is a Virus? • • Diseases caused by a virus: Common cold or influenza (flu) Rabies Small pox AIDS (Autoimmune deficiency syndrome) Viruses can only replicate or make more viruses when they are in a living cell (the HOST) • Tiny particles of genetic info (RNA or DNA) surrounded by a protein coat They must HIJACK the cells machinery (Organelles) Most Viruses attack only one kind of organism Example: bacteriophage is a virus that only attacks bacteria (phage means “to eat”) How a Virus Infects A Cell • • • • • • Virus attaches to bacterial cell wall injects DNA into bacterial cell Virus directs cell to make viral nucleic acid Virus DNA and proteins assemble into new virus Bacterial cell opens and the virus particle is released Virus that infects bacteria is called a BACTERIOPHAGE Making it simple! Start 2:30 End: 6:20 Lytic Cycle Lysogenic Cycle 3 ways To Prevent Infectious Disease 1. 2. 3. Vaccinations Practice Good Hygiene Avoid people you know are sick Vaccines • • Weakened OR deactivated forms of pathogen that are introduced into your body to cause YOUR immune system to produce antibodies that fight off the pathogen Many different vaccines have been made to protect people from viruses and bacteria •4 Ways Vaccines Work 1) Click Here! How Vaccines Work VIDEO Weaken the Virus • viruses are weakened so that they reproduce themselves very poorly once inside the body • Body is able to make “memory B cells” to protect patient against the virus for life + only one or two doses need for life long immunity - may cause a mild version of disease and people with weakened immune systems (cancer or AIDS) cannot get them 2) Inactivate the Virus Viruses are completely inactivated (or killed) with a chemical the virus is still "seen" by the body and cells of the immune system that protect against disease are generated + anybody can get this vaccine - Many doses are required • • 3) Use Part of the Virus just one part of the virus is removed and used as a vaccine (proteins on the surface of the virus) can be used when an immune response to one part of the virus (or bacteria) is responsible for protection against disease + a few doses= long lived immunity • • 4) Use Part of the Bacteria Make vaccine by inactivating toxin with a chemical (the toxin, once inactivated, is called a toxoid). • Toxoid no longer causes harm and body create immune cells against this specific toxin • Make vaccine using the sugar coat of specific bacteria • Body build immunity against bacteria with that specific sugar coat - requires many doses to build immunity • Protects the body from disease • specialized cells and organs that work together to protect you from pathogens Barriers that keep pathogens out of the body • The Skin • largest organ in the body, provides a protective barrier between you and the outside environment. • Mucous membranes • line nasal and respiratory organs • air you inhale may contain pathogens • become trapped in mucus, fluid secreted by mucous membranes • then moved by cilia to opening to be blown out or swallowed, where stomach acids take care of them • Stomach acids, sweat, and tears are all barriers to block out pathogens. Inflammatory response to tissue damage • If you cut your finger, Inflammatory responses begins as soon as pathogens enter the body: 1. Blood vessels near the cut expand 2. Plasma fills the spaces between cells, carrying white blood cells to injury (macrophages-WBC that engulf and destroy pathogens), and platelets seal the cut 3. Area surrounding cut may become red, swollen, and inflamed? Why? 4. Another sign: fever • raises your body temperature to help fight infection by making your body less suitable for the growth of harmful bacteria • macrophages also work better at higher temperatures First Line and Second line of Defenses: NONSPECIFIC DEFENSE Immune response attacks specific pathogens using specialized cells and proteins • Specific Defense Macrophages and other specialized white blood cells called T cells and B cells T Cells- white blood cells that attack and kill harmful cells B-cells- white blood cells that make antibodies. Antibody- Y-shaped protein that attaches to a specific foreign substance= antigen= found on the surfaces of bacteria and viruses. lock and key model= antibody and antigen causes the antigen to clump together and become harmless clumped antigens are then engulfed by macrophages or destroyed by T cells The granulocytes often take the first stand during an infection. They attack any invaders in large numbers, and "eat" until they die. The pus in an infected wound consists chiefly of dead granulocytes. A small part of the granulocyte community is specialized in attacking larger parasites such as worms. The macrophages ("big eaters") are slower to respond to invaders than the granulocytes, but they are larger, live longer, and have far greater capacities. Macrophages also play a key part in alerting the rest of the immune system of invaders. Macrophages start out as white blood cells called monocytes. Monocytes that leave the blood stream turn into macrophages. The dendritic cells are "eater" cells and devour intruders, like the granulocytes and the macrophages. And like the macrophages, the dendritic cells help with the activation of the rest of the immune system. They are also capable of filtering body fluids to clear them of foreign organisms and particles. Results from exposure to specific pathogen • Weakened or deactivated form of a disease-causing agent • When introduced, it activated immune system to make antibodies to the pathogen Created by transferring antibodies made from one organism into another organism 1. Person bitten by a dog or bat 2. Often acquired before birth may be given antibodies taken from people who have been • As the fetus develops, it receives vaccinated against rabies. antibodies from its mother Why? Rabies can progress faster than an infected person can produce antibodies • Newborns also receive antibodies in their mother’s milk When Immune system cannot fight off an infection, drugs may be used to help rid the body of pathogens. drugs that either kill bacteria only or prevent their reproduction • Penicillin, first antibiotic in 1928: used to be very resistant but with antibiotic resistance it has become less effective Antibiotic Resistance: ability of bacteria to survive treatment with certain antibiotics When a colony of bacteria is exposed to an antibiotic, most of the bacteria are usually killed Some will be resistant and those are the ones that survive and reproduce, passing resistance off to their offspring This happens every time the antibiotic is used Why do you think Antibiotic Resistance has become a big problem in many parts of the world? Critical Thinking: 1. Animals infected with the virus that causes rabies often salivate excessively and are apt to bite other animals even when unprovoked. In a paragraph, explain how these symptoms lead to the spread of the virus. 2. Getting vaccinated is much safer than getting the disease that the vaccine prevents. However, like any drug, vaccines are capable of causing side effects. Describe the benefits and risks of vaccinations. 3. The ability of bacteria to resist antibiotics has become an increasing public health problem. This problem is due to the overuse and misuse of antibiotics. Suppose that one of your friends always take antibiotics when he or she is sick. Write a letter to your friend explaining the problem of antibiotic resistance.