1. The Human Immune System

2. First lines of defense tears antibacterial enzymes
saliva antibacterial enzymes
mucus linings traps dirt and microbes
skin prevents entry
stomach acid low pH kills harmful microbes
“good” gut bacteria out compete bad

3. Pathogens = disease causing micro-organisms bacteria virus fungi
protozoa
parasites
prion

4. Second lines of defense
Involves white blood cells
Non-specific response
invading pathogens are targeted by macrophages (WBC)
Specific response
lymphocytes produce chemicals called antibodies that target specific pathogens

5. Phagocytes

6. The Phagocytes Phagocytes are the “soldiers” of the immune system
They are responsible for, killing and digesting invading microbes.
The process of swallowing microbes is known as phagocytosis.

7. Phagocytes Monocytes and macrophages
Provide a non-specific response to infection

8. Phagocytosis
The bacteria are digested by enzymes, and then absorbed by the phagocyte
During infection, hundreds of phagocytes are needed.
Pus is dead bacteria and phagocytes!

11. White Blood Cells

12. Lymphocytes Provide a specific immune response to infectious diseases.
There are 2 types: -
- T-cells B-cells

14. B Cells & T Cells B and T cells perform specialized tasks
B cells recognize antigens and then (as plasma cells) mass-produce specific antibodies
Helper T cells coordinate the attack
Killer T cells once activated, destroy virus-infected cells
T cells “T” = Activated in Thymus

15. Antigen
An antigen is any substance that creates an immune response, from a virus to a sliver.
It can also be incorrectly identified as an invader (allergy response)

18. Bozeman: Immune System

20. When a virus or bacteria invade the body it is engulfed by a macrophage cell. The macrophage then signals T-cells to cause B-cells to multiply.

21. Macrophage

22. The B Cells get the message from the T-Cells, to produce antibodies which disable the invading bacteria.

24. Antibody Vs Antigen
Antigen (the virus)

28. Immune System Can Attack Itself
This is the case of autoimmune diseases:
multiple sclerosis
lupus
some forms of arthritis
diabetes
allergies

29. Allergies
The immune system thinks the foreign invader is harmful to you so it “reacts”

31. Anaphylaxis = Life Threatening Reaction

34. Interferon
A small “natural” protein that acts against microbes – ESPECIALLY Viruses
Until recently it was thought that IFN acted ONLY against viruses.

35. Defense & Repair: DVD – Online https://www. youtube. com/watch
(KHS Library #824)

37. Neutrophils "eat" pathogens and send off distress signals.
Monocytes are triggered to turn into pathogen-eating macrophages.
Eosinophils attack parasites
Basophils contain granules filled with histamine and other compounds related to allergies.
The second set of cells — the lymphocytes — is slower to react.
As the generalized campaign goes forward, a second set of specialized cells known as lymphocytes begins a more specific and enduring attack. The stars of this more adaptive immunological defense system — killer T cells, helper T cells, and B cells — work in concert to destroy infected cells. The B cells mature into plasma cells that generate highly specific
antibodies capable of producing lasting immunity.
T cells coordinate the immune system response.
Any material that triggers this immune response is called an antigen.