Immune System Chapter 40
Germ Theory of Disease Idea that microorganisms can cause infectious disease. Disease: any change that disrupts normal body function. What are the 5 main agents that cause disease? Virus, bacteria, protists, worms, fungi Robert Koch developed a set of rules or Postulates for testing whether or not an organism caused a disease.
Koch s Postulates Problems with the postulates: - Can t always grow the pathogen - Who is going to be a test subject?
How can agents be transmitted? Physical contact Airborne coughing, sneezing, talking Contaminated water or food Infected animals VECTORS Ex: rats carry plague, mosquitos carry malaria, ticks carry lyme, mice carry Hanta virus
What methods do we use to fight infectious diseases? Antibiotics chemicals that kill bacteria inside the body Vaccines exposure to dead/weakened prevent bacterial or viral disorders Sanitation kill pathogens outside the body Pesticides chemicals that kill on plants Sterilization high heat that kills Refrigeration slows bacterial growth Washing hands!
What is the function of the immune system? To recognize, attack, destroy and remember pathogens that try to cause disease in our body.
Two types of defense systems Nonspecific defense Specific defense
Nonspecific Defenses Does not discriminate between any type of threat. Protects against and attacks them all! Provides physical, chemical or cellular barrier. Your 1 st and 2 nd Line of Defense 1st Line of Defense includes: 1. Skin barrier(dead cells, keratin, ph, bacteria) 2. Mucous membranes 3. Secretions (sweat, saliva, tears, enzymes)
2 nd Line of Defense: Inflammatory Response and Fever Blood vessels dilate Phagocytic WBC s move in Animation Body temp increase FEVERS (slows down pathogen growth;speeds up WBC response) Interferon chemical secreted by infected cells to protect other cells from viral infection.
and if they get through that The 3 rd line (last line) of defense will come into play: Specific Immune Defense!
Specific Defense Two pathways that will occur: 1. Humoral antibodies are made 2. Cell Mediated destruction of infected cell or pathogen Key players: Lymphocytes!! 1. B cells 2. T cells
Humoral Immunity Antibodies - attach to a specific pathogen s antigens. Immobilizing pathogen. Antigens - foreign surface markers B cells are immune cells involved Steps: 1. B cells recognize antigen 2. B cell differentiates into plasma cells 3. Plasma cells make/release antibodies 4. B cell differentiates into memory B cells
Antibodies Every antibody is made for one specific pathogen. Receptor sites made to bind to specific antigens (marker on pathogen) Binds like lock and key! Purpose of antibodies: Flags or disables the pathogen for death
Cell-mediated Immune Response Killer (cytotoxic) T-cells attack cells with antigen markers. Destroy with chemicals that perforate membranes. Memory T cells will be active for future exposures. Macrophages clean up the mess.
The Key Player: Helper T cell Helper T s activate cell mediated and humoral responses. Can form memory helper T s. Macrophage
Video Video
What happens the next time you are invaded by the same pathogen? What cells will be activated? MEMORY CELLS!
Second Exposure Memory B cells and T cells are immediately activated Symptoms rarely occur because the pathogen is quickly recognized and destroyed.
How can you gain immunity against pathogens? Video Get a vaccination or get exposed!
Immunity Types Active Immunity Injection of a weak or mild form of pathogen. Attenuated form of disease. Natural exposure to pathogen. Long-term immunity. Passive Immunity Injection of antibodies from another organism; temporary immunity or treatment.
What can go wrong with the immune system? Here are just a few problems that could occur in your lifetime. Section 40-3
Allergies An OVERREACTION of the immune system Occurs after 2 nd exposure Allergen attaches to mast cell s antibodies. Mast cell then releases histamine. Result: Itchiness, mucus production, sneezing, watery eyes etc. Anaphylaxis life threatening reaction to allergen
Asthma Narrowing of the air passages by the spasm contractions of the smooth muscle. Chronic disease Reaction to antigens or stress related.
Other Diseases Autoimmune Disorders Your own immune system is attacking you! Production of antiself antibodies. Ex: Multiple Sclerosis, Rheumatoid arthritis, Lupus, Celiac disease Immunodeficient Diseases Failure of the immune system to develop normally. Pathogen could be destroying WBC s. Ex: AIDS, Boy in the Bubble