1. The body’s defenders

2. Contents Pathogens and disease Major types of defense
Nonspecific or innate immunity
External defenses
Internal defenses
Specific or acquired immunity
Lymphocyte activity
Types of acquired immunity
Humoral (antibody-mediated) response
Cell-mediated response
Immunity to secondary infection
Active immunity
Passive immunity
Blood groups and transfusions
Immune disorders

3. Pathogens and disease
Fungi
Viruses
Protozoa
Large parasites
Bacteria

4. Two major types of defenses
INNATE (NONSPECIFIC)
IMMUNITY
Rapid responses to a
broad range of microbes
ACQUIRED (SPECIFIC) IMMUNITY
Slower responses to
specific microbes
External defenses
Internal defenses
Skin
Mucous membranes
Secretions
Phagocytic cells
Antimicrobial proteins
Inflammatory response
Natural killer cells
Humoral response
(antibodies)
Cell-mediated response
(cytotoxic
lymphocytes)
Invading
microbes
(pathogens)

5. Innate (nonspecific) immunity First line: External defenses

6. Innate immunity Second line: Internal defenses
Microbes
MACROPHAGE
Vacuole
Lysosome
containing
enzymes
Phagocytic cell 1
Phagocytes
Attach to and ingest invading microorganisms
Initiates the inflammatory response
Macrophages – migrants or in lymph organs
Antimicrobial proteins
Complement system – lysis of invading cells, triggers inflammation
Interferons – activate macrophages, prevent cell-to-cell spread 2 3 4 5 6

7. Innate immunity Second line: Internal defenses (con’t.)
Inflammatory response
Chemicals involved
Histamines
Prostaglandins
Chemokines
Pyrogens

8. Innate immunity Second line: Internal defenses (con’t.)
Natural killer (NK) cells
Patrol body
Attack virus-infected body cells and cancer cells
Apoptosis (cell death) in cells attacked
Coelomocytes in invertebrates function in nonspecific immunity

9. Specific (acquired) immunity Third line of defense
Lymphocytes
Found in blood and lymph
Types
B – cells – mature in marrow
T – cells – mature in thymus
Helper
Cytotoxic
Display specificity to antigens (antibody generator)
Have membrane-bound antigen-receptors

11. Two types of specific immune responses
B and T cells generate clones of
short-lived activated effector cells
long-lived memory cells

12. Antibody action

13. Immunity – memory cells initiate a faster, more efficient response upon reinfection

14. Own system develops antibodies
Active immunity
Own system develops antibodies
Develops naturally in response to infection
Develops following immunization
Long-lasting protection but may take a long time
Passive immunity
Antibodies are passed from mother to fetus via the placenta
Antibodies are passed from mother to infant via breast milk (colostrum)
Antibodies may be injected into a nonimmune person
Immediate, short-term protection

15. Blood groups and transfusions
Problems with transfusions and transplants
Antigens on RBC’s will determine a person’s blood type: A, B, AB, O blood
Another RBC antigen: Rh factor  Rh+ or Rh-

16. Immune disorders/diseases
Allergies – hypersensitive responses to antigens called allergens
Autoimmune diseases – immune system loses tolerance for self and turns against certain molecules of the body
Immunodeficient diseases
Inborn or primary
Acquired or secondary
AIDS – HIV attacks helper T cells
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