1. The Immune System

2. Words To Know… Pathogen – A disease-causing agent.
Histamine – a chemical which causes an inflammatory response.
Vascular – Having to do with blood vessels.
Antigen – a substance that causes an immune response.
Antibody – A defensive protein produced by the body towards a specific antigen.

3. The Immune System
The immune system is a system of cells, structures and processes in an organism that protects against pathogens and diseases.

4. There are Two immune responses
Non-Specific
No Target Enemy
Specific
Specific Target Enemy

5. First Lines of Defense SKIN Largest organ of body
Protects against water loss, chemicals, pathogens
Covered in Bacteria and yeasts
MUCUS
Found inside orifices (holes)
Protects against chemicals, pathogens and debris

6. Non-Specific Response
Second line of Defense
Inflammation
Temperature
Proteins
White Blood Cells

7. Second Lines of Defense - Inflammation
A biological response by vascular tissues to harmful stimuli:
Pathogens
Damaged cells
Irritants/allergies
4 Cardinal Signs
Pain
Redness
Swelling
Heat
What causes these 4 signs?
Pain – excess blood in the area puts pressure on pain receptors
Redness – oxygenated blood in area
Swelling – excess blood/fluid in area
Heat – carried in by blood

8. Second Lines of Defense - Fever
Temperature (Fever)
The process of elevating core temperature in response to a pathogen
An elevated tem can inhibit the growth of disease-causing bacteria
Can also destroy good cell proteins
Fever
Ave. temp: 98.6 F
Low-Grade:98.6 –
High-Grade: over 103 F

9. Second Lines of Defense - Proteins
Membrane attack complex (MAC)
Various proteins will form a ring on pathogen surfaces, causing them to leak out and die
Interferon
A protein released by infected cells
Causes nearby cells to produce an enzyme that prevents the virus from entering and reproducing.

10. Second Lines of Defense - WBCs
White Blood Cells
Cells of the immune system
Protect the body against pathogens and foreign bodies

11. White Blood Cells Neutrophils Most abundant
Engulf bacteria, killing it and themselves
Natural Killer Cells
Largest WBC
Best defense against cancer
Secretes a cytotoxin that disrupts infected cell membrane
Macrophages
Means “Big Eater”
Eats and kills pathogens and infected cells

12. White Blood Cells Helper T Cells Activates Cytotoxic T and B cells
Cytotoxic T Cell
Seeks out ‘labeled’ and infected body cells and destroys them
B Cells
Labels invaders for future destruction

13. Specific Response
The specific line of defense targets specific pathogens.
Those pathogens who have survived the first two rounds now face the Immune Response!
4 Specific WBCs are central to the immune response:
Macrophages
Helper T Cells
Cytotoxic T Cells
B Cells

14. Steps to Immune Response:
Virus infects a cell; cell displays viral antigen (red flag)
Step 2:
Macrophages ‘eat’ virus/cell; they now display same viral antigen
Step 3
Receptor proteins on Helper T Cells bind to those viral antigens

15. Steps to Immune Response:
Helper Ts don’t attack, but activate B and Cytotoxic T Cells
Step 5
Activated B cells turn into plasma cells and release lots of antibodies
Step 6
Antibodies attach to viruses to mark them for destruction

16. Steps to Immune Response:
Antibodies cause viruses and antigens (red flags) to clump together, making it easy for macrophages to find and ‘eat’ them
Step 8
Activated Cytotoxic T cells destroy infected cells