Chapter 40 The Immune System and Disease

40-2 The Immune System  Immunity – The process of fighting against infection through the production of cells that inactivate foreign substances or cells.  Nonspecific Defenses  First line of defense – Function is to keep pathogens out of the body.  skin, mucus, sweat, and tears  Second line of defense – Function is to destroy pathogens that enter the body.  Inflammatory response—nonspecific disease reaction to tissue damage  Fever—Elevated body temperature that slows down or stops the growth of pathogens.

 Specific Defenses  Immune response – A series of specific defenses that attack the invading pathogens.  Antigen – substance that triggers an immune response  Viruses, Bacteria, and other pathogens  Humoral Immunity  Antibodies – proteins that recognize and bind to antigens (pg. 1038). Produced by B Cells, also called Plasma Cells.  Cell-Mediated immunity  Body’s defense against its own cells that have become cancerous or infected with viruses.  B cells (lymphocytes) – provide immunity against pathogens in body fluids (Humoral Immunity)  T cells (lymphocytes) – provide defense against pathogens in living cells (Cell-Mediated Immunity)

 Types of T cells  Killer T - track and destroy invaders  Helper T – create memory T cells  Suppressor T – release substances that shut down killer T cells  Memory T – cause secondary response if the same antigen enters the body again at a later time

 Acquired Immunity  Active immunity— Appears after exposure to an antigen.  Vaccination—The injection of a weakened or mild form of a pathogen to produce immunity.  Natural exposure—Fighting an infection.  Passive Immunity – Antibodies produced by other animals against a pathogen are injected into the bloodstream. Lasts only a short time.  Mother to Child—Through breast milk or across the placenta.  Administration of Antibodies—Used to treat people who have a disease or are travelling to where a disease is prevalent. Example: vaccine that contains antibodies like rabies vaccine

40-3 Immune System Disorders  Allergies – allergens (antigens) – attach to the mast cells, which induce inflammatory response.  Histamines – activated mast cells release histamines, which increase blood flow to surrounding area.  Asthma – respiratory disease often caused by allergies.  Autoimmune Disease – immune system makes a mistake and causes the body to attack its own cells.  Type I Diabetes, Multiple Sclerosis, Rheumatoid Arthritis

 HIV and AIDS  Viral infection that destroys helper T cells, causing the normal immune response to break down.  HIV retrovirus – Carries genetic information in RNA instead of DNA.  Page 1046 – shows infection of HIV.