1. Go to Section: The Immune System

2. Go to Section: The Immune System The body’s primary defense mechanism May destroy invaders by engulfing them by special cells or by chemically marking them for destruction and elimination Functions by being able to recognize proteins on the surface of cells It can distinguish between self and non-self –The non-self, or invading foreign proteins are referred to as antigens

3. Go to Section: Nonspecific vs. Specific Two types of defense mechanisms –Non-specific – physical and chemical barriers 1 st line of defense - Keep pathogens out of your body –Done by skin, mucous, sweat and tears »The secretions contain lysozyme, an enzyme which breaks down the cell walls of bacteria

4. Go to Section: Section Outline 2nd line of defense – inflammatory response –If pathogens do enter your body, phagocytic white blood cells move into the area to destroy the bacteria –The immune system also releases a chemical that increases your body temperature »The fever kills the bacteria because they can only exist in a narrow temperature range. »The fever also increases heart rate so wbc can get to the infection site faster. Section 40-2

5. Go to Section: Skin Wound Bacteria enter the wound Phagocytes move into the area and engulf the bacteria and cell debris Capillary Section 40-2 Figure 40–7 The Inflammatory Response

6. Go to Section: Specific Defense A specific defense against a pathogen is called an immune response –Pathogens that trigger this response are called antigens These may be viruses, bacteria or other pathogens such as fungi, parasites, etc. The immune response attacks the particular disease-causing agent with a response especially for that pathogen There are two types of wbc’s that recognize specific antigens –B cells – humoral immunity – pathogens and antigens in body fluids –T cells – cell-mediated immunity – pathogens and antigens inside living cells

7. Go to Section: Interval between exposures First exposure Second exposure Time Antibody Concentration Section 40-2 Primary and Secondary Immune Responses

8. Go to Section: Acquired Immunity Two types of acquired immunity –Active – appears after exposure to an antigen May be natural (the body fights an infection) May be artificial (through vaccination) –Vaccine – injection of a weakened form of an antigen to produce an immune response –Passive – receiving antibodies to fight off an infection – only lasts a short time because the body will eventually destroy the foreign antibodies May be natural – antibodies are passed to a baby through the placenta and through breast milk May be artificial – vaccines may contain antibodies to protect and prevent disease

9. Go to Section: Section Outline Immune System Disorders A.Allergies B.Autoimmune Diseases C.HIV and AIDS Section 40-3

10. Go to Section: Allergies An overreaction of the immune system –Allergy causing antigens enter the body and attach themselves to certain white blood cells These white blood cells initiate the inflammatory response –Produce chemicals called histamines –Asthma – a chronic respiratory disease where the air passages become narrower than normal, causing wheezing, coughing and difficulty breathing May be treated with medications that relieve the symptoms of asthma

11. Go to Section: Autoimmune Disorders The immune system has the ability to recognize self and non-self –When the immune system makes a mistake and attacks its own cells, it produces an autoimmune disease Examples –Type I diabetes – insulin-producing cells of the pancreas are destroyed –Multiple sclerosis – antibodies destroy the functions of the neurons in the brain and spinal cord –Lupus – attacks normal connective tissue, leading to inflammation and pain in the joints –some of the autoimmune diseases may be treated with immune suppressing drugs However, this therapy is not used often or must be monitored carefully

12. Go to Section: HIV and AIDS AIDS is an autoimmune disease that results from infection with HIV –Normally healthy patients die from: microorganisms that don’t normally cause disease from extremely rare forms of cancers and pneumonia from pathogens that healthy people can normally fight off HIV –is a virus that can evade the defenses of the immune system and attacks key cells in the immune system

13. Go to Section: Transmission and Prevention of HIV Transmitted through bodily fluids such as blood, semen, vaginal secretions and breast milk –Through any form of sexual intercourse –Through shared needles that are contaminated with infected blood –Through contact with blood or blood products –From infected mother to child, through pregnancy, birth and/or breast feeding