Immunity Chapter 40

What is a disease? Any change that disrupts the normal function of the body Not caused by injury Causes = Genetic (DNA mutation), Pathogens (bacteria), Environmental (smoking)

Pathogens Disease-causing agents “sickness- makers” infectious diseases (ex.) protist, bacteria, virus, worm, fungi

Germ Theory of Disease Ancient Times = diseases caused by curses, evil spirits, vapors, etc… 1800’s = Louis Pasteur and Robert Koch = infectious diseases were caused by microorganisms of different types called germs

How do you know what causes the Disease? Kochs Postulates: 1. Pathogen found in sick organism and not healthy organism 2. Pathogen is isolated and grown in a lab 3. Pathogen is placed on a healthy organism and it develops the disease 4. Pathogen from injected host is isolated and it is identical to the original pathogen

Koch Postulate Example Allen Steere (1975) –Several children in a small area with the same symptoms (rash, arthritis) –All children had tick bites –Ticks have the bacteria Borrelia burgdorferi –Isolate the bacteria, grow it, put it in lab rats –Lab rat gets sick with same symptoms –bacteria isolated from sick rat –Ticks with the bacteria cause Lyme Disease

Why do Pathogens like us? Our body temperature is good for growth watery environment (most pathogens dehydrate easily) abundance of nutrients (eat us or our food)

How does a pathogen infection result in Disease? Viruses = take over and kill cells, disrupt normal function of the cell Bacteria = 1) destroy tissue for food or 2) release harmful toxins

How does a pathogen infection result in Disease? Protists = mostly by feeding off of our nutrients and sometimes producing harmful toxins Worms = Disrupt normal cell function, eat tissue, eat nutrients Fungi = disrupt normal cell function (usually skin cells)

How do diseases spread? 1. Physical Contact: coughing, sneezing, physical contact 2. Contaminated food and water 3. Infected Animals (vectors)

Antibiotics Discovered by Alexander Fleming (1928) Compounds that kill bacteria without killing other cells within the host Most are naturally occurring (fungi, sulfur based) and some are synthetic They have no effect on viruses Over-the-counter drugs only treat the symptoms

Immunity Chapter 40

Your Immune System Fights off infections Produces cells that search and destroy foreign cells (immunity) 2 types of Defenses: Specific and Non-Specific

Non-Specific Defenses 1.The Skin: (1 st line of Defense) - keeps pathogens out of the body - protective seal - If broken, pathogens can get in (swelling, redness, pain)

Non-Specific Defenses Body Fluids: (1 st line of Defense) –Saliva and Tears = contain lysozyme that breaks down bacteria cell walls –Oil and Sweat = make the skin acidic which kills bacteria too –Mucus = traps pathogens that try to enter the mouth and nose –Stomach Acid = destroy any pathogen that makes it to the stomach

Non-Specific Defenses 2. Inflammatory Response (2 nd Line of Defense) - white blood cells are produced - blood vessels expand (more circulation) - Fever = increased body temperature kills some pathogens and it also increases the heart rate so WBC get there faster

Non-Specific Defenses Interferon –how your body reacts to a viral infection –released from infected cells to prevent other cells from being infected –slows down the infection by blocking viral replication

Specific Defenses Cell Types: - B-Cells = protect against infections in the body’s fluids - T-cells = protect against abnormal cells and infections within cells

Specific Defenses More Cell Types: - Antibodies = proteins that attack pathogens - Memory Cells = cells that remember how to kill specific pathogens - Antigens = a substance that triggers an immune response (start button)

Humoral Immunity 1. A pathogen infects a body fluid 2. Antigens trigger the production of more B-cells and Plasma Cells 3. Plasma cells produce antibodies 4. Antibodies kill the pathogen 5. Memory cells are made to remember how to kill that pathogen next time

Cell-Mediated Immunity 1. Cells become cancerous or are infected with a virus, fungi, or protist 2. T-Cells turn into 4 types and the Stop the Infection: –Killer T-Cells: destroy the pathogen –Helper T-Cells: produce memory T-cells –Memory T-cells: remember how to kill pathogen for next time –Suppressor T-cells: tell killer T-Cells to stop

Organ Transplants Every cell has a marker on it that identifies it to the t- cells (ID card) T-Cells check the ID’s and destroy anything that doesn’t belong We can transplant organs by: –1. Picking a donor with similar ID cards –2. Suppressing the t-cells after a transplant

Active Immunity Vaccinations: –A weakened dose of a pathogen –Safe 1 st response –20 vaccinations currently available –Natural and synthetic

Passive Immunity Antibodies produced by one animal are placed inside another animal Only lasts a short time because the foreign antibodies will be killed by T-cells Mothers pass on immunity to their children through the placenta and breast milk

Allergies Overreaction of the immune system allergens (pollen, dust, bee stings, food) trigger a immune response Histamines - chemicals released during an allergic reaction –cause sneezing, watery eyes, mucus, increased blood flow, etc...

Auto-Immune Diseases When the immune system attacks the body’s own cells instead of foreign cells Multiple Sclerosis (MS) = immune system attacks the nervous system –loss of mobility –numbness –loss of balance

AIDS Caused by the HIV virus the HIV attacks and kills T-Cells Without T-Cells, body is unable to fight disease