Understanding Immunity: Defending Against Infection

1. Unit 11 – ImmunityGuided Notes The Fight Against Infection

2. What is IMMUNITY? Definition: - the ability of the body to resist disease - our immune system protects us from pathogens (any organism/protein-structure that cause disease) - in fact, our immune system is what helps us recognizepathogens as foreign objects so we can destroy them

3. Where do diseases come from? Years ago… People believed they got diseases from evil spirits and spells! Now… People now know diseases come from microorganisms and viruses! Remember Redii and Pasteur’s experiments??!! Pasteur Link

4. Causes of Disease • Viruses: tiny particles made of a protein shell that invade cells and make the cell replicate (double) their genetics; they can look like spiders with legs; receptors on surface • Bacteria: small microorganisms that either breakdown the tissue of the organism or release toxins • Worms, Protists, and Fungi: they are all agents that invade the host causing damage or even death

5. Causes of Disease • Viruses - NOT cells (can’t reproduce); not living - attach to the cell - inject their genes (DNA or RNA) - cell makes more viruses - have “antigens” on surface (fit to cell receptors like a lock and key)

6. Causes of Disease • Bacteria - tiny, one-celled organisms; living - most are GOOD for you (90%); bad ones treated with antibiotics - found in yogurt, cheeses, butter, sauerkraut, pickles, olives, soy sauce - also have “antigens” on surface; our bodies attack these with “antibodies” Three types: bacilli = rod shaped cocci = circle shaped spirilla = spiral shaped

7. Examples VIRUSES herpes HIV cold sores common cold (flu) West Nile BACTERIA strep throat E. Coli tuberculosis anthrax Botulism pneumonia

8. How Are Diseases Spread? • Physical contact - touching, sexual contact, coughing, sneezing, not washing hands • Contaminated Food and Water - undercooked meat, untreated water, unrefrigerated food • Infected Animals - mosquito, rabid animals, fleas (Bubonic plague history pg. 1034 in Biology)

9. Ways to Prevent Disease • Skin - hard to penetrate (pass through) the layers of dead skin; enzymes in our secretions break down bacteria’s membrane • Inflammatory response - a nonspecific defense reaction to tissue damage caused by injury or infection • Immune response - the body’s specific defenses that attack a pathogen using the antibody/antigen attack

10. Line of Defense # 1 Skin - many layers of dead skin keep pathogens out • blood clots and white blood cells at cut sites often prevent infection • Pus and redness often indicate the skin has become infected An infected toe nail; note the redness and infection

11. Line of Defense # 2 Inflammatory Response (non-specific) • activated when pathogens enter the body and trigger the release of chemicals called histamines • histamines cause the capillaries to swell by increasing blood flow to exposed areas and increase mucus production • See body areas become inflamed or swollen ex. Bee sting, pollen • Interferons: cells that make a protein for other cells so they resist viral infection; block viral replication (almost like choking them) • This response usually indicates an allergy

12. Inflammatory Response continued • allergies- the body’s overreaction to antigens • antigens that cause allergic reactions are called allergens • common allergens include ragweed pollen, dust, dust mites

13. Line of Defense # 3 Immune Response (specific) • Activated when other defenses do not work • Triggered by an antigen (on the surface of foreign substances that invade the body & cause disease) • White blood cells recognize these antigens and release antibodies (proteins that stick to antigens); after “sticking” to the antigen, the antibodies attack the antigen, destroying it

14. Line of Defense # 3 continued • Certain white blood cells called memory B cells can remember specific antigens and are able to fight these antigens the next time they infect the organism • This is why you do not get Chicken Pox twice! • Your body fights it the first time, makes antibodies, and you get well; if you come around Chicken Pox again, your memory B cells “remember” the disease, already know how to make the antibodies to fight it, and you do not get sick again

15. Line of Defense # 3 continued • Review: Jobs of a White Blood Cell • Tag and recognize foreign objects • Engulf and/or destroy bacteria/viruses/old cells • Make antibodies Recognize and tag… Engulfing…

16. Immune Response continued Immune Response Passive Immunity Active Immunity • Temporary (short term) • type of immunity that develops from being given antibodies • Ex. mother’s milk; through placenta (diffusion of antibodies to baby from mother) • long term • type of immunity from the body having the disease once, making antibodies, and recognizing it in the future • also includes vaccinations

17. Immune Response continued More on Active Immunity • Vaccination (an injection of a weakened form of a pathogen to produce immunity) • Weak pathogen triggers antibody production; so now when you get infected with the “active” form of the disease, you have antibodies ready • More than 20 serious human diseases can be prevented by vaccination • Ex. Polio, measles, mumps, chicken pox, flu

18. Vaccinations continued… • Vaccines “jump start” your immune system; gives you a head start on beating the disease • Getting a vaccine increase the ability to fight a pathogen because you make antibodies against the pathogen’s antigens

19. Diseases When the body is unable to fight off a pathogen, a failure in homeostasis occurs and the organism develops a disease; organism can become ill or even die!!! In some cases, when the immune system makes a mistake and attacks the body’s own cells, it is called an autoimmune disease

20. Autoimmune Diseases • In autoimmune diseases, the body produces “antiself” antibodies • These “antiself” antibodies are sent out to destroy the organism’s own body tissues • Ex. Multiple Sclerosis (MS), Type I Diabetes 2050: Finally mad enough to act, the Earth makes antibodies against the human race

21. AIDS - An Immunodeficiency Disease • AIDS is not an autoimmune disease • AIDS is considered an immunodeficiency disease because a virus destroys certain white blood cells in the body so that the immune system does not work properly • AIDS is caused by the virus HIV; leaves the body with no protection to fight other diseases

22. AIDS continued • Most people who die who have AIDS die from another minor infection • AIDS can be transmitted through sexual intercourse, shared needles, contact with infected blood, and through child birth including breast-feeding • AIDS cannot be transmitted by sitting next to someone!

23. Ways to Prevent Disease Your body has numerous responses to prevent disease: skin sneezing coughing stomach acid

24. What can you do to keep healthy? • Wash your hands many times a day using soap • Live in a clean house: change sheets regularly, eliminate carpet, use antibacterial cleaners • Cover your mouth when you yawn, cough, sneeze • Use a tissue to blow your nose and throw it away • Avoid touching bathroom door handles when leaving bathrooms

25. Diseases of Interest • Leukemia - form of cancer associated with high number of white blood cells; treated with chemotherapy/radiation • Polio – contagious disease caused by a virus that affects the nervous system; vaccine required • Lupus – an autoimmune disease where the body attacks its own tissues causing joint pain, heart problems, and even iron deficiencies (anemia); no cure • Multiple Sclerosis (MS) – an autoimmune disease where nerve cells of the body are attacked causing pain, loss of balance, slurred speech, and tremors