1. Infectious Diseases and The Immune System

2. 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

3. Identifying Pathogens
Robert Koch
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

4. 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

5. 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

7. 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

8. 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

9. 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

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

12. 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

13. 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

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

16. 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

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

18. 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

19. Spreading Pathogens
Air
Food
Water
Contact
Animal bites