1. Aim: How does our body defend us from pathogens?

2. Pathogens Any disease-producing agent!
Examples: virus, bacterium, fungus, or parasite.

3. 1st Line of Defense Skin Mucus Tears in eyes Acid in stomach
Show an apple and discuss the skin’s job.

4. How do these things help to protect us?
Tears and sweat: has enzymes that are able to destroy pathogens .
stomach has HCL to kill bacteria.
Hair and mucus trap potential disease causing pathogens.

5. 2nd Line of Defense
The Immune System

6. Cellular Components: White Blood cells
Large cells with a nucleus.
Defenders of the body.
Two Types of white blood cells:
Phagocytes: engulf and destroy bacteria
Lymphocytes: produce antibodies

7. Immune System
Made of proteins, cells, and tissues that identify and defend the body against foreign chemicals and organisms

8. How does our immune system identify foreign cells?
They are proteins on our cells (like an ID tag)
Antigen
IF the ID tag identifies the invader as not belonging to the body (non-self), then the ID tag is called an antigen.

9. If the Antigen is foreign….. What will the immune system do?
ATTACK IT!!!!

10. Phagocytes – Engulf the Pathogens

11. Lymphocytes:Produce antibodies
They can make antibodies, which are their weapons against the foreign antigens.
Very specific, only one antibody will fight only a certain antigen!
Antibodies & Antigens are both proteins!!

12. Antibodies They are weapons that fight against pathogens Pathogen
Use screw motivation
Antigens

13. How are nuts and screws similar to antigens and antibodies?
Antibodies are made specifically to
match the shape of the antigen.
1 antigen = 1 antibody
What does this remind you of?
Do screw and nut motivation

14. How do antibodies destroy pathogens?
When the antibody attaches to the antigen, it breaks open its cell membrane
Or, the antibody attaches to the antigen, and a phagocyte will know to engulf it
Balloon and pin motivation

15. Our Immune System has a good memory!
The first response is
relatively slow and
weak because time
is needed for enough
WBCs to form and
defeat the pathogen.
The second response
to the same pathogen
triggers a quicker and
stronger response.
** After the first response, the immune system “remembers ”specific pathogens by leaving behind specific WBCs that protect the body for years (memory cells).