Infectious Disease and the Immune System Ch. 39

1. Infectious Disease and the Immune SystemCh. 39

2. What are Infectious Diseases? • Pathogen- bacteria, virus, fungi, protozoa, etc… • Any organism that disrupts homeostasis • Infectious Disease- change in homeostasis by a pathogen • Foreign pathogen • Symbiotic pathogen that has changed location • Body is too weak for symbiotic relationship

3. Types of Diseases? • Infections diseases Pathogens • Genetic disease gene mutations • Trisomy 21 (Down’s Syndrome) • Environmental toxin exposure • Cirrhosis • Malnutrition limited food supply • Scurvy • Cancer Carcinogens • Lung Cancer • Brain tumor • Diabetes Genetics/Malnutrition

4. Identifying a New Disease • Robert Koch; 1876 • Isolated anthrax from dead animals and injected into healthy ones • Healthy animals died of disease • Isolate pathogen in new dead animals and found it to be the same anthrax • Koch’s Postulates: • Same pathogen must be found in the host in every case • Pathogen must be grown on a culture plate • Once grown, the pathogen must give a healthy organism the disease • Pathogen in the new host and the old host must be the same

5. Spreading Disease • 4 methods: 1) Direct Contact -colds, STDs, Flu Carriers- transmit disease but are not effected by it Incubation period- time it takes after infection for symptoms to appear 2) By Object -food poisoning 3) Airborne transmission -Strep throat 4) Vectors -insects, birds, farm animals -Malaria; mosquitoes -Black Plague; fleas on rats

6. Disease Patterns • Endemic Disease: always present in the population; cases fluctuate with seasons ex. Cold, flus, food poisoning • Epidemic Disease: small population see dramatic increase in a new or uncommon disease ex. SARS • Pandemic Disease: global spread of disease ex. HIV/AIDS; H1N1

7. Pathogen Attack! • Pathogens damage host cells through toxins proteins/compounds that: -inhibit cellular functions -destroy the plasma membrane -produce fever -inhibit cell signaling Botulin neurotoxin -most powerful discovered so far; 75 ng can kill a human -prevents neurotransmitter release -causes muscle paralysis -used to make BOTOX

8. The Immune System • Immune system- various methods of defending, isolating, and removing pathogens from the body • Innate Immunity • Nonspecific defenses against all pathogens • Acquired Immunity • Defense against specific pathogens that is built over time • Made from Antibody immunity and Cellular immunity

9. Innate Immunity • Levels of defense: 1) Skin- protective barrier covering the body 2) Secretions- mucus, oil, sweat, tears, and any other fluid used to wash away pathogens • Also contain lysozyme enzyme 3) Inflammation- increase blood flow and temperature of infected area to kill pathogens • Caused by Histamine, AA hormone released by Basophils and Eosinophils(white blood cells)

10. Innate Immunity 4) Phagocytes- white blood cells that kill pathogens with phagocytosis • Endocytosis of bacteria Types of Phagocytes: • Macrophages- white blood cell in tissue • Neutrophil- second wave if macrophages are not enough • Monocytes- travel in the blood to infection site and become macrophages Over time infections produce pus (collection of living and dead macrophages)

11. Innate Immunity 5) Interferons- protective proteins that cover cells so viruses cannotattach to host cells • Specific for different types of host cells • Also produce antiviral proteins to stop virus reproduction Macrophages from the innate immune system are used to build the acquired immune system

12. Acquired Immunity • ID system through antigens and antibodies • Antigens- proteins in the cell membrane used in cellular communication • A-type Blood A-type antigens • Bacterial membrane antigens signal attachment mechanism • Antibodies- proteins in the blood produced to attach to specific antigens • If the antibody finds the antigen is was made for; that organism attached to those antigens is destroyed

13. Lymphatic System • System for monitoring tissue fluid and filter body fluids for infection • Lymph- tissue fluid inside lymph vessels • Travels through capillaries and veins on the Lymph system • Return tissue fluid to blood in the shoulders • Lymph nodes- mass of tissue for filtering lymph with lymphocytes (white blood cells) • Tonsils- filter out pathogens we breath in • Spleen/Thymus Gland- store lymphocytes • Lymphocytes react with pathogens to build antibodies • Create Antibody and Cellular Immunity

14. Antibody Immunity • Infection occurs and macrophages eat pathogens • Antigens from pathogens are placed on the macrophage membrane • Lymphocytes (Helper-T cells and B cells) bind to antigens and create plasma cells • Plasma cells produce 2000 antibodies/sec to kill infection • Memory-B cells and antibodies stay in blood to stop infection quickly if it returns

15. Cellular Immunity • Infection occurs and macrophage eats pathogens • Antigens from pathogens are placed on the macrophage membrane • Cytotoxic (Killer) T cells activate and release perforinon to pathogens • Perforin eats through membranes, killing the pathogens Over active reaction can lead to autoimmune disorders -body tissue is attacked -transplanted organs are attacked

16. Passive vs. Active Immunity Passive: Natural- Antibodies pasted down from mother/breast milk Artificial- Take antibodies from organism already immune from disease Active: Vaccine- Inject person with weak or dead pathogen; body easily kills it and makes antibodies Cowpox is a vaccine for Smallpox

17. Homework: HIV/AIDS paper • Write a 1 page essay on HIV: • How it spreads? • How does it effect the immune system? • What is AIDS? • What are methods of controlling the spread of HIV? • Are there ways to cure HIV? A lot of content so be brief in your explanations