Understanding Disease Agents and Immune Systems

1. Immune system

2. Pathogen=Disease causing agent • Any change (not including injury) that disrupts the normal functions of the body • Caused by • Agents- • bacteria,viruses,fungi • Materials in the environment • (cigarette smoke • Inherited- hemophilia

3. Germ Theory • Louis Pasteur/Robert Kouh-1800 said disease caused by germs…what about before? • What rules do we follow for identifying the microorganism that causes a specific disease. • Koch’s Potulates • Pathogen identified in sick organism not healthy one • Pathogen grown in pure culture • Healthy organism becomes sick when infected with pure culture pathogen • Pathogen extracted and must be same as original pathogen

5. Agents of Disease • Our body is great for pathogens • Suitable temperature,watery,lots of nutrients • We already have loads of yeast and bacteria in/on us- large intestine, mouth which are either harmless or helpful • What do the pathogens do? • destroy cells,release toxins, block bloodflow,remove nutrients,disrupt bodily functions

6. Virusis • Invade and replicate on the cells using the cells own RNA or DNA (that’s why we cant kill a virusis) Bacteria-Most are harmless Harmfull cause disease in two ways 1.breaking down tissue of the 2.infected organism or releasing toxins Protists ex Malaria, Sleeping sickness feed off the nutrients of infected host Worms- same as protists Fungi- Most harmless- ringworm etc can be deadly

7. How are Diseases spread? • Physical contact • To help cover your mouth, wash your hands • Contaminated Food and Water • All food contains bacteria • Infected Animals • The animals that carry the pathogen from person to person are called =vectors

8. How do we fight them? • Antibiotics- kills the bacteria not the cells • Over the counter drugs (careful) these treat the symptoms not eh disease.

9. 40.2 Immune system • Immune systems function is to fight infection through the production of cells that inactivate foreign substances or cells. This is immunity. • 1st line of defense is your skin, mucus, sweat, tears contain lycoenzyme and salt. Oil and sweat glands produce acidic environment. • Mouth nose and anus are protected by mucus, cilia that line your nose and throat help push pathogens away from your lungs (Lugie) stomach has acid.

10. Second line of defense • Inflammatory response • Mast cells release histamines that cause the blood walls to be leaky. White blood cells then cross over into the tissue. Many are phagocytes that engulf and destroy bacteria. Tissue swells you say ouch! • Immune can release chemicals that increases (yep, you make the temp) =Fever . High temp stops or slows the growth of many pathogens (Bacteria can replicate every 20 minutes) • For viruses we make proteins called interferon

11. Specific Defenses= immune response • Antigen = substance that triggers a response Two types • Humoral immunity made of B cells (lymphocytes) they provide immunity against antigens and pathogens in body fluids) • Pathogen enters the body and its antigens are recognized by Bcells which grow and divide rapidly, producing large numbers of plasma and memory B cells. (memory B cells stay behind after pathogen is gone so you will not be reinfected

12. Cell mediated Immunity • T cells defend against abnormal cells and pathogens inside living cells. (both are lymphocytes) • They do this by T cells dividing into Killer T cells, helper T cells, suppressor Y cells and memory B cells. • T cells kill invador • Helper T produce memory T cause secoundary response if pathogen ever comes back • When attack is under control suppreassor T cells shut down Killer T • Problems Transplants

13. Acquired immunity is when we deliberately infect a person either by exposure or a Vaccination • Passive immunity- limited time ex- Moms milk, rabies shot, Malaria medication etc…