1. The Immune System
Chapter 24

2. What you need to know! Several elements of an innate immune response
The differences between B and T cells relative to their activation and actions.
How antigens are recognized by immune system cells.
The differences in humoral and cell-mediated immunity.
Why Helper T cells are central to immune responses.

3. Immune System
Function: fight infection using cells to destroy invading substances
Two divisions:
Nonspecific (innate immunity)
Specific

4. Nonspecific (Innate immunity)
Nonspecific = doesn’t matter which disease you have
First line of defense
Second line of defense
Interferon

5. First Line of Defense Prevent the enemy from breaching the perimeter
Skin, mucus, cilia are tools your body uses to deny the enemy access to your body

6. Second Line of Defense
Should the enemy breach the perimeter a second line of defense is necessary
Inflammatory response
White blood cells move into the damaged area surround and destroy the invaders
Fever
Histamine released by damaged tissue trigger a rise in body temperature
Cooks invaders
Raises heart rate

7. Inflammatory Response
Wound
Skin
Phagocytes move into the area and engulf the bacteria and cell debris
Bacteria enter the wound
Capillary

8. Animations http://www.youtube.com/watch?v=CmbWE3jLUgM

9. Interferon Proteins that “interfere” with viral reproduction
Infected cells release interferons to help healthy cells prevent viral reproduction

10. Lymphatic System
Works with the immune system to clean blood and make white blood cells
Consists of nodes the thymus and bone marrow

11. End Part I

12. Specific Immune System
Strategies the body uses to defeat a particular disease (acquired immunity):
B cell humoral immunity
T cell-mediated immunity

13. Acquired Immunity Triggered by a foreign molecule (antigen)
Immune response to antigens is either:
More white blood cells, or
Antibodies
An antibody is a protein in blood that attaches to a specific antigen

14. Immunity Resistance to specific invaders
Active immunity: your immune system makes the antibodies
learned by natural exposure or vaccination
Passive immunity: receive premade antibodies
Fetus from mother’s blood
Baby from mother’s milk
antivenin

15. Lymphocytes White blood cells usually found in the lymphatic system
Specialize into B or T cells depending on where they mature
B cells = bone marrow
T cells = thymus
Both cells use antigen receptors in their membranes to detect invaders

16. Humoral Immunity Antigen binds to a B cell’s antigen receptor
B cells divide rapidly into two new cells
Plasma cells
Make antibodies
Memory B cells
Remember the invader for next time
Antibodies attach to the invaders to disrupt function or to target them for macrophages

17. Humoral Immunity

18. Cell-Mediated Immunity
T Cells kick-in when antigens are embedded in our own cells (cancerous or infected)
Macrophages identify antigens and embed them in their membrane
Helper T cells identify the antigen and stimulate cytotoxic cells to annihilate any cell with the specific antigen
Cytotoxic cells (killer T cells) stimulate the targeted cell to kill itself (apoptosis)

19. Cell Mediated Activity
Helper T cell activates killer T cells and B cells
Macrophage
T cell binds to activated macrophage
Helper T Cell
Killer T Cell
T Cell
T cell, activated by macrophage, becomes a helper T cell
Antigens are displayed on surface of macrophage
Infected Cell
Killer T cells bind to infected cells, disrupting their cell membranes and destroying them

20. Animations