Understanding Immunity: The Body's Defense System

1. What is Immunity? • The Immune System

2. Immunity • Immunity • The ability of the body to fight infection and/or foreign invaders by producing antibodies or killing infected cells. • Immune System • The system in the body responsible for maintaining homeostasis by recognizing harmful from nonharmful organisms and produces an appropriate response.

3. Foreign Invaders • Called Pathogens • Viruses, bacteria or other living thing that causes disease/immune response. • Antigens • Toxins that pathogens produce that cause harm to an organism.

4. Parts of the Immune System • Blood - White Blood Cells in particular. • Lymph nodes • Thymus Gland – Produces T Lymphocytes • Bone Marrow – Produces B Lymphocytes

5. How does the body fight infection/foreign invaders? The Body’s THREE lines of Defense First Line of Defense – The Skin • Provides Physical and Chemical barriers • Physical – hard to penetrate, made of indigestible keratin • Chemical – tears, sweat

6. Second Line of Defense – Nonspecific Immune Response These are defenses the body uses no matter what the invader may be. These defenses include: • Phagocytosis – done by Macrophages • Natural Cell Killers • Inflammation - caused by release of Histamine from leukocytes • Fever – caused by histamines. The fever (high temp) kills invaders by denaturing their proteins. Macrophage: A phagocytic cell found in the liver, spleen, brain and lungs. Travels to all areas of the body to find and eat pathogens.

7. Third Line of Defense –Specific Immune Response This is a specific response to a specific pathogen/antigen. • The response involves the creation of Antibodies.

8. Antibodies • Y-shaped protein molecule. • Made up of variable and constant regions. • Made up of Heavy and Light chains. • Produced by B-Lymphocytes • Function: Recognize antigens, bind to and deactivate them. • Note: Variable region recognizes the anitgens.

9. The Pathway of Specific Immune Response Step 1 Pathogens eaten by Macrophage Step 2 Displays portion of Pathogen on surface Step 3 Pathogens Helper-T cell recognizes Pathogen

10. Activates B- Cell Activates Cytotoxic T- Cell Memory B-Cell Memory T-Cell Antibodies Kills Infected Cells

11. Carried out by T-Cells Infected cells are killed by Cytotoxic T –Cells. Carried out by B-cells Antibodies are produced and dumped into blood stream. Antibodies bind to antigens and deactivate them. Cellular Immunity .vs. Antibody Immunity Cellular Immunity Antibody or Humoral Immunity

12. Immune Response Explained • Antigen infects cells. • Macrophage ingests antigen and displays portion on its surface. • Helper T- Cell recognizes antigen on the surface of the macrophage and becomes active. • Active Helper T-Cell activates Cytotoxic T-Cells and B-Cells. • Cytotoxic T-Cells divide into Active Cytotoxic T-cells and Memory T – Cells. • Active Cytotoxic T-Cells kill infected cells. • At the same time, B-Cells divide into Plasma Cells and Memory B- Cells. • Plasma cells produce antibodies that deactivate pathogen. • Memory T and Memory B cells remain in the body to speed up the response if the same antigen reappears. • Supressor T-Cells stop the immune response when all antigens have been destroyed.

13. Immune Response Summary Displays copy of antigen on surface of cell Antibody Immunity Cellular Immunity

14. Primary .vs. Secondary Immune Response • Primary Immune Response • This is a response to an invader the First time the invader infects the body. • No measurable immune response for first few days. • Next 10 – 15 days antibody production grows steadily • Secondary Immune Response • A more rapid response to an invader the 2nd time it invades the body. • Antibody production increases dramatically and in a much shorter time period..

15. Passive .vs. Active Immunity • Active Immunity This is immunity where the body is “actively” producing antibodies to fight infection. Ex: You have a throat infection and you are actively creating antibodies to fight it. Vaccination:An injection of a weakened strain of an infectious microbe (pathogen) that causes the body to undergo active immunity (produce antibodies). • Passive Immunity This is immunity where antibodies are given to a person from the blood of another person or animal. This immunity only lasts for a short period of time.

16. Disease • Disease does not allow the body to function normally. • It can effect one organ or an entire system

17. Infectious Disease • Caused by tiny organisms called pathogens • Can be viruses, bacteria, fungi, or protists • Can come from a person, contaminated object, animal bite, or the environment. • The immune system distinguishes between the different types of pathogens and reacts according to type • Once pathogen is in the body, it can damage individual cells in an organ or attack an entire system

18. Types of Infectious Diseases • Common cold • Influenza • Athlete’s Foot • AIDS • Strep Throat

19. Colds • Caused by a virus in the respiratory system • Once in the body, the virus multiplies and attacks mucus membranes of nose and throat causing sore throat, runny nose and fever. • Because it is caused by a virus, it cannot be treated with antibiotics.

20. Flu • Influenza, known as “the flu”, is a highly contagious viral infection on the respiratory system. • Causes fever, aches, and more severe cough than the common cold and lasts longer

21. AIDS • AIDS- Acquired immunodeficiency syndrome • Caused by human immunodefiency virus HIV • Virus attacks cells in the immune system making the person unable to fight off other pathogens that may attack the body.

22. Strep Throat • A contagious disease caused by a bacterial infection • Symptoms include fever, pain, redness and swelling of throat and tonsils • Symptoms can be mild or severe

23. Non-Infectious Diseases • Not caused by pathogens in the body • Not spread from organism to organism • Caused by malfunctions in the body systems that are either inherited or caused by environmental factors

24. A List of Non-infectious Diseases • Diabetes • Parkinson’s Disease • Skin cancer • Asthma