Infectious Disease and the Immune System Ch. 39

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

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

Identifying a New Disease Robert Koch; 1876 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: Koch’s Postulates: 1)Same pathogen must be found in the host in every case 2)Pathogen must be grown on a culture plate 3)Once grown, the pathogen must give a healthy organism the disease 4)Pathogen in the new host and the old host must be the same

Spreading Disease 4 methods: 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

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

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

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

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)

Innate Immunity 4) Phagocytes- white blood cells that kill pathogens with phagocytosis – Endocytosis of bacteria Types of Phagocytes: 1)Macrophages- white blood cell in tissue 2)Neutrophil- second wave if macrophages are not enough 3)Monocytes- travel in the blood to infection site and become macrophages Over time infections produce pus (collection of living and dead macrophages)

Innate Immunity 5) Interferons- protective proteins that cover cells so viruses cannot attach 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

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

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

Antibody Immunity 1)Infection occurs and macrophages eat pathogens 2)Antigens from pathogens are placed on the macrophage membrane 3)Lymphocytes (Helper-T cells and B cells) bind to antigens and create plasma cells 4)Plasma cells produce 2000 antibodies/sec to kill infection 5)Memory-B cells and antibodies stay in blood to stop infection quickly if it returns

Cellular Immunity 1)Infection occurs and macrophage eats pathogens 2)Antigens from pathogens are placed on the macrophage membrane 3)Cytotoxic (Killer) T cells activate and release perforin on to pathogens 4)Perforin eats through membranes, killing the pathogens Over active reaction can lead to autoimmune disorders -body tissue is attacked -transplanted organs are attacked

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

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