1. The Body’s Defenses
California Standards 10.a., b. & c.

2. Pathogens Pathogens are disease causing agents such as: 1. bacteria
2. viruses
3. prions and
4. single cell organisms

3. First Line of Defense
Skin: prevents pathogens from entering the body

4. Skin = the first line of defense
The skin is the organ which defends the body from infection by blocking the entry of pathogens.

5. 2. Mucous Membranes: found in your nose and throat and stop the entry of pathogens into your body.

6. Second Line of Defense Inflammatory Response Temperature Response
Proteins
White Blood Cells

7. 1.Inflammatory Response
A series of events that suppress infection and speed recovery
Histamine: increase blood flow by dilating blood vessels.
White blood cells invade infected area
Swelling and redness occurs

8. When the skin is punctured pathogens are allowed to enter the body.
capillary

9. Injured or damaged cells release the chemical histamine which causes the blood vessels to dilate increasing blood flow to the area. This blood flow causes swelling and redness to the area.

10. Increased blood flow bring white blood cells that attack and destroy pathogens. The presence of ‘puss’ at a wound is the presence of white blood cells.

11. 2. Temperature Response 1. Higher temperature called a fever
2. Bacteria do not grow well at high temperatures
3. Enzymes are destroyed or denatured

12. Temperature Response
Basically, the temperature is a response that is helpful in fighting pathogens because bacteria do not grow well at high temperatures.

13. Bacteria and Antibiotics
Antibiotics are specifically used to kill bacterial infections. They do nothing for viral, or virus caused, infections.

14. 3. Proteins 1. Complementary System made up of 20 different proteins.
2. Punctures cell membrane of bacteria
3. Interferon released to fight viruses

15. 4. White Blood Cells
Neutrophils
Macrophages
Natural Killer Cells

16. Neutrophils Engulf and destroy pathogens
Release chemicals that kill bacteria and themselves

17. Macrophages Kill and ingest pathogens
Clear dead cells and other debris
Found in spleen and lungs

18. Natural Killer Cells Attacks cells infected with pathogens
Puncture cell membrane
Detect and kill cancer cells

19. Nonspecific Defense: Skin Mucous membranes Inflammatory response
Temperature
Protein
White blood cells

20. Third Line of Defense

21. Specific Defense Against Disease
The last type of defense against invading organisms is the specific line of defense. This defense by your body attacks specific pathogens and in the process produces antibodies that in the future can attack that specific pathogen if it occurs again.

22. Third Line of Defense
Immune Response: consists of an army of cells that combat specific pathogens
Antigen: a substance that triggers an immune response
Antibody: a ‘Y-shaped molecule that is produced by plasma cells when exposed to an antigen.

23. Non-functioning immune response
A person’s immune response is not functioning well if it is unable to fight pathogens. This is because their body cannot produce the specific antibody for that pathogen. AIDS is just such a disease because a patient’s body inability to defend itself against invading organisms.

24. Antibodies and Antigens
An antibody is produced by your body in response to a specific antigen.
An antigen is a foreign substance which causes the body to produce a specific antibody.

25. Antibodies attacking an antigen
‘Y’ shaped antibody

26. Antibodies
Antibodies are substances formed by the human body in response to foreign proteins entering the body.

27. Resistance to Disease Immunity – resistance to a particular disease.
Vaccination – a medical procedure used to produce immunity.
Vaccine – a solution of dead or modified pathogens that can no longer cause disease.

28. Vaccines and Infection
Vaccines are effective in preventing disease because they are dead or modified pathogens with antibodies directed against a specific pathogen.

29. The End