Infectious Diseases and The Immune System

The Immune System Molecules, cells, and organs in the body Interactions form a system designed to protect an individual from: outside invaders damaged internal cells

Identifying Pathogens Robert Koch 1843-1910 Studied Anthrax Koch’s Postulates Suspected pathogen occurs in diseased body Isolate suspected pathogen Inoculation of a healthy animal  disease This pathogen is isolated and studied *Epidemiologists still use this procedure to study disease

Nonspecific Defenses Innate Able to distinguish foreign tissues and organisms! Reaction occurs regardless of the pathogen First Line of Defense Barriers Skin Mucous Membranes Tears Saliva Stomach pH Ciliated linings

Second Line of Defense The Inflammatory Response Chemical Agents Lysozymes Histamine The Inflammatory Response Series of events that suppress infection and speed recovery Injury Histamine - Chemical messenger Increased blood flow WBC squeeze out and destroy by phagocytosis Result Redness-swelling-heat-pain

Second Line of Defense Nonspecific Effector Cells Neutrophils & Macrophages Phagocytic white blood cells Natural Killer Cells Attack infected cells Attack cancer cells Temperature Response Fever! Response to infection Greater than 1030F is dangerous, 105oF can cause death! Proteins: Complement: plasma protein, activated by pathogens Interferon: produced by infected cells

Specific Defenses: The Immune System Specific- antibody/antigen Memory- antibodies remaining that remember antigens Organs: Bone Marrow stem cells Thymus T Cell maturation Spleen WBC/Filter Lymph Nodes Filter Tonsils

Lymphocytes WBC Differentiation B Cells Directs the production of antibodies (5 types) T Cells H=detect infection, tell B cells to produce antibodies C=attack virus infected cells S=alerts immune system to stop fighting

Recognizing a Pathogen Antigen  recognized foreign substance Proteins, lipds, polysaccharides,pollen, toxins, venom Cell receptors Immune System responds to antigens Specific! Memory!

Immune Response Cell Mediated Immune Response Target is known: MEMORY Two-part assault on pathogen Macrophage engulfs pathogen: displays fragment of pathogen=TROPHY Interleukin-1 released= activates T cells attaches to H-T Cell Cell Mediated Immune Response Interleukin-2 Stimulates Helper T Cells Stimulates Cytotoxic T Cells Stimulates B Cells

Immune Response Humoral Immune Response B Cells Occurs at the same time the cell mediated occurs Antibodies produced by plasma cells 30,000 molecules produced per second Bind to pathogen and inactivate pathogen! Attract phage cells that engulf pathogen

Primary and Secondary Immune Response Memory Cells Lymphocytes recognize and attack Long term protection against reinfection Effective throughout life

Immunity and Vaccination Ability to resist an infectious disease Primary immune response and survive Vaccination: dead/weakened pathogen Jenner 1796 Milk Maids & Cow Pox (vaccinus – from cows) Immunization against Smallpox Pasteur treats Rabies Salk  injectable Polio vaccine Booster Shots - Restore Immunity against some diseases Tetanus Varicella

Problems of the Immune System Allergy Response to a “harmless” antigen Symptoms are usually mild… Antihistamines stop the release of histamine

Asthma Autoimmune Disease Respiratory disorder that causes bronchioles to narrow Many different triggers (smoke, allergens) Autoimmune Disease Rare Body reacts against its own cells Examples Multiple Sclerosis Lupus erythematosis Rheumatoid Arthritis

Spreading Pathogens Air Food Water Contact Animal bites