Infectious Diseases and The Immune System The Immune

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 1. Suspected pathogen occurs in diseased body 2. Isolate suspected pathogen 3. Inoculation of a healthy animal disease 4. 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 p. H �Ciliated linings

Second Line of Defense �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 1030 F is dangerous, 105 o. F 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 �Filter

Lymphocytes �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 WBC Differentiation

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

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 �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