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Immune System Keeping you safe Good health is something you may take for granted. Until you or someone close to you gets sick. Then the value of good health becomes all too obvious Why do you get sick? How do you get better? These are questions that can be answered! Disease Disease: any change other than an injury that disrupts the normal functions of the body • Some are inherited • Some are caused by the environment • Some are caused by bacteria, viruses, and fungi Pathogens Pathogens: disease causing agentssuch as- bacteria, virus, and fungi Patho- sickness agent Gen- to create Infectious diseases- diseases caused by pathogens infecting the body Germ Theory of Disease I. • History of disease origin belief curses evil spirits night vapors Dispel History of Disease Origin Beliefs Louis Pasteur Robert Koch Koch’s Postulates Observations of both Koch and Pasture was that: Disease is caused by microorganisms (germs) Led to the Germ Theory of Disease World filled with microorganisms Which microorganism actually causes the disease? Here’s the scenario: 1975 Allen Steere at Yale University: Answered the question- which microorganism causes a specific disease! Small area of Connecticut- 39 children, several adults suffered from joint pain and inflammation. Most cases in summer/ fall Suspected could be pathogen carried by an insect. Many children reported infection began with what they thought was an insect bite! Bite followed by expanding rash Bull’s Eye Rash Lyme Disease Steere called it Lyme Disease Linked skin rash to tiny deer tick Dr. Willy Burgdorfer • found spiral shaped bacterium in the ticks (got to name the bacteria Borrelia burgedorferi) • found same spiral shaped bacterium in the patients Borrellia bergdorfori • injected bacteria into lab mice • mice got arthritis and other symptoms like the children • Steere recovered the bacteria from mice- passed on those bacteria to healthy mice • Healthy mice then got sick Koch’s Postulates Burgdorfer and Steere relied on Koch’s (Pronounced Cock’s) Postulates Robert Koch Developed series of guidelines still used today to identify pathogens that cause a specific disease • 1) Pathogen should be found in sick organism and not that of a healthy one • 2) Pathogen must be isolated and grown in lab in pure culture • 3) When purified pathogens placed in a new host, new host get same disease that infected original host • 4) Injected pathogen should be reisolated from the second host, should be identical to the original pathogen Pathogens Agents of Disease: Why is the human body so good for pathogens? right temperature moist environment abundance of nutrients Large Intestines: harbors dense colonies of bacteria Mouth, throat, tissues surrounding eyeballs: bacteria and yeast Vaginal area: lots of yeast-how do we get yeast infections? Antibiotics Antibiotics kill off the normal bacteria that keep yeast in check, with free reign of the area, yeast go to work and over produce causing a curd like substance to be produced, a.k.a.- yeast infection. Question? How do pathogens cause disease? bacteria can break down the tissues • parasites include protists, fungi and worms • some remove nutrients from digestive system • others destroy blood cells and neurons bacteria can release toxins in the body toxins: poisons that produce illness by disrupting bodily functions Botulism – C. botulinum Tetanus- C. tetani found in soil one of most powerful toxins/ does not allow muscles to go back to relaxed state. Anthrax Spread of Disease How Diseases are Spread: Some infectious disease can be spread from person to person through: • • • • • • Coughing Sneezing Physical Contact Contaminated water Food Infected animals Vectors Vectors: animals, such as ticks and mosquitoes, spread many diseases Vector: organisms that carry disease-causing agents What was the vector for Lyme disease? Often the key to stopping disease from spreading Avoid tall grass will keep the deer tick away Wash Hands Good Hygiene Avoid infected people STI’s (STD’s) Sexually Transmitted Infections (STI’s) diseases by exchange of bodily fluids also known as having sex some of the most dangerous pathogens are spread by having SEX STI’s (STD’s) Syphilis- caused by bacteria in body fluids Gonorrhea- caused by bacteria in body fluids Chlamydia- caused by bacteria Hepatitis B&C- caused by virus AIDS- caused by virus STI’s (STD’s) Genital Herpes- caused by virus Fighting Infectious Diseases: If prevention fails (keeping pants on!) there are drugs that can possibly help to fight pathogens. Most useful drugs- antibiotics Antibiotics: compounds that kill bacteria without harming the cells of animals or humans by interfering with the cellular processes of microorganisms Antiviral Drugs: inhibit ability of viruses to invade cells and multiply Drugs 2 methods: destroy cell wall of bacteria, so cannot live (penicillin) • Fleming tried to grow Staphylococcus (a bacterium), became contaminated with Penicillium notatum. Fungus inhibited the growth of the bacterium. Blocks protein synthesis in the ribosome of bacteria (streptomycin) • Antibiotics have NO effect on Virus Immune System II. With all the pathogens scurrying about, why aren’t we always ill? We have a protective system known as the Immune System: a series of defenses that guard against disease. some are simple barriers others are pistol packing security guards Non-Specific Defenses The Simple Barriers 1st line of defense: • keep pathogens (the bad guys) out • Skin is crucial, the most important barrier! Non-Specific Defenses When blood shed begins (skin torn apart) pathogen allowed to enter and infect Shows the pinnacle importance of skin We’d be hopeless with out the skin Mouth and Nose: Mucous- traps virus and bacteria Cilia- the gatekeeper pushes pathogens away from lungs Stomach acid and digestive enzymes: Non-Specific Defenses Full on blitz, sneak past mucous and the gatekeeper (cilia) and reach stomach Destroy pathogens Lysozymes: enzymes that break down bacteria cell walls • Found in mucous, saliva, sweat and tears • 2nd line of defense: (first line fail) Inflammatory response is next in line Inflammatory response Inflammatory response: a non-specific defense reaction to tissue damage caused by injury or infection! Steps: Pathogen infects tissues Blood vessels dilate (expand) White blood cells (leukocytes) leak from dilated vessels and go to infected areas WBC are phagocytes: engulf and destroy bacteria Phago= to eat Cyte= cell Inflammatory response Hypothalamus: releases endogeneous pyrogenes (chemicals) that increase core body temperature • This is a fever! Higher temperature slows down or stops growth of pathogens Inflammatory response Higher temperature from fever increases heart rate so that WBC get there faster Higher temperature speeds the activity of WBC’s and the reactions that help repair damaged tissues Interferons- help resist viral infections inhibit the synthesis of viral proteins therefore blocking viral replication Specific Defenses: Non-specific failure! Immune response becomes specific and varied- known as the IMMUNE RESPONSE Triggered by Antigens: carbohydrates, proteins, or lipids on a pathogen that trigger the immune response Immune response can be humoral immunity or cell- mediated immunity Specific Defenses: Humoral- immunity against pathogens in body fluids (blood and lymph) Produced by lymphocytes • B- lymphocytes produce antibodies Antibody: protein that helps destroy a pathogen • Generally “Y” shaped • Two identical antigen binding sites that bind to antigen Specific Defenses: Influenza Virus: Here comes trouble with a capital “I” (do antibiotics help?) Influenza enters- has antigen on surface Antibody recognize virus as foreign Begin to clump on (pile on top) Specific Defenses: Phagocytes recognize clump (gobble gobble) engulf and destroy mass! How are antibodies produced? Custom-made- specific to a specific antigen! B-cells (B= bone marrow) made early in fetus development: Genes coding for antibodies rearrange slightly differently in each B-cell Specific Defenses: At end of development, due to slight difference, there are millions of different B-cells, each of which can recognize a different antigen So, when pathogen enters the body, a small fraction of B-cells will recognize as foreign. B-cells very happy and reproduce (split) many copies made, known as plasma cells. Specific Defenses: Plasma cells release the antibodies into blood stream to seek out and destroy the pathogen. Plasma cell activation and regulation monitored by T-lymphocytes (T= thymus) Specific Defenses: Cell Mediated Immune Response: Helper T regulate production of antibodies by B-cells, but other T cells can attack pathogens directly- called Killer T cells (cytotoxic T cells) Killer T’s transfer proteins into membrane that cause it to be “leaky” so fluid will leak out of the cell. Pathogen dies! Killer T- why tough to do organ transplant: Specific Defenses: We will recognize our own organs by surface proteins Everybody has different surface proteins that will be recognized as foreign, immune system will attack! Rejection is painful even at the organ level! (That’s why people resort to toilets) Must find very similar surface markers and take drugs to suppress immune response to prevent rejection Permanent Immunity Been known for more than 2000 years (measles/small pox- got once, never again) Known as permanent immunity- done by memory B and T cells that are ready and armed Active Immunity Edward Jenner: produced first vaccine Permanent Immunity Cowpox sufferers never got small pox? Could you infect someone with cowpox to prevent small pox? Decided to infect Jamie Phipps with fluid from cowpox sores. Jamie got cowpox. Permanent Immunity Two months later, the mad scientist Jenner took it one step further, infected Jamie with small pox. Surprise! Jamie did not die a horrible death from small pox! The first vaccine discovered. Vaccination Vaccination: injection of a weakened or mild form of a pathogen to produce immunity (vacca means cow- from cowpox and cow hands and milk maids and farmers and other people who deal with cows that gave Jenner the brilliant idea to play with little Jamie) Immunity from a vaccine is known as ACTIVE immunity because body of recipient has the ability to respond immediately to exposure to the pathogen. Passive Immunity: If antibodies from another animal for a particular pathogen are injected into our bodies- the antibodies produce a passive immunity (only a few weeks) while they are in the body. Often given to travelers (who will be in tropical areas for a limited time) Maternal immunity is a passive immunity (placenta/ milk provide antibodies) III. Immune System Disorders Although the immune system defends the body against all the evil powers of the world, sometimes disorders occur. Immune System Disorders Two Main Types of Disorders: Immune system over reacts to antigens (the “girl response”) – produces discomfort or even disease Immune system is weak (the “boy response”) Immune System Disorders Allergies (overreaction) Result when antigens from allergens (things that create allergies, such as pollen, or another girl in the picture, or dust mites) bind to mast cells (another type of immune cell in the nasal passage) Allergen antigen bind to mast cell, mast cell release chemicals known as histamines that increase blood and fluid flow to area Immune System Disorders Histamines responsible for sneezing and runny nose and eyes Antihistamines for allergies? Can result in asthma- smooth muscle contractions reduce size of passageway of air in lungsbreathing difficult- usually triggered by particular antigen (i.e. pollen) Autoimmune Diseases Immune attacks own body- yup, you guessed it, an autoimmune disease! Could be caused by an infection Example: strep throat (streptococcus bacteria) if left untreated will cause the immune system to produce antibodies to destroy the bacteria. Antigens on streptococcus so similar to cardiac cells, immune response could also attack heart Results in rheumatic fever: antibodies and killer T cells kill and scar cells of the heart lining (pericardium) and valves Autoimmune Diseases Example: • Juvenile onset diabetes • Multiple Sclerosis • AIDS Example of cells of immune system weakened by infection Autoimmune Diseases Early 1980’sPeople started coming down with infections including: Protozoans in the lungs Fungal infections of the mouth and throat Karposi Sarcoma (a rare skin cancer) Normal immune systems could battle these infections off like the weak advances Iraqis Doctors soon realized that their patients’ immune systems must be compromised. HIV / AIDS Way the disease was spread made them suspect a virus. 1983- HIV identified (Human Immunodeficiency Virus) HIV / AIDS The nuts and bolts: Virus enters body (HIV) Attaches to receptors on T cells T cells normally help recognize and aid immune response Body does not produce antibodies to HIV HIV replicates within cells of immune system (because it is inside cells, less likely to bind to antibodies) NO CURE FOR AIDS Spread by contact with infected blood or other body fluids (Oral/Anal still going to get it) Abstain Faithful, get checked, latex condom