1. The Fight Against Infectious Diseases

2. Innate (means you are born with it) Immunity
Innate Immunity – The body’s first line of defense against any and all pathogens.
Skin is the first barrier
Pathogens encounter your body’s secretions.
Mucus, sweat, tears and saliva.

3. How Do Secretions Help?
Mucus traps pathogens that enter the respiratory and digestive tracks. The mucus is swallowed and the stomach’s acidic gastric juice (HCl) destroys the bacteria and toxins.
Sweat, tears and saliva all contain the enzyme lysozyme which breaks down the cell walls of some bacteria.

4. Response to the Damage to Body Tissue
Inflammation – occurs when bacteria or other pathogens damage body tissue.
Four Symptoms
Redness, Swelling, Pain and Heat
Symptoms not cause by pathogen but rather your body’s response to the pathogen.

5. What Kills Pathogens?
Phagocytes are White Blood Cells (WBC) that destroy pathogens by surrounding and engulfing the pathogen.
Phagocytes include:
Macrophages, neutrophils, and monocytes
Dead phagocytes and body fluid make pus.
Phagocytes cannot destroy viruses.
Anti-viral proteins called Interferon protect cells from viruses by interfering in the viral replication cycle.

6. Acquired Immunity
Acquired Immunity – The gradual build-up of resistance to a specific pathogen over time.
Occurs when the immune system recognizes antigens found on foreign substances and responds by producing antibodies against the foreign substance.

7. Lymphatic System
Lymphatic system helps defend the body and maintains homeostasis by keeping body cells constantly bathed in tissue fluid.
Tissue fluid collects in lymph vessels and is called lymph, which is filtered through lymph glands.
Lymph glands contain lymphocytes (WBC) and filters pathogens from the lymph.

8. Antibody Immunity Occurs after innate and acquired immunity.
If an infection is not controlled and acquired immunity occurs, a type of lymphocyte called a T cell becomes involved.
Two types of T cells
Helper T cells – interact with B cells
Killer T cells – release enzymes directly into pathogens, causing them to lyse and die.

9. Antibody: B cell
B cells – lymphocytes that when activated become a plasma cell and makes antibodies, which are released into the bloodstream.
Memory B cells are B cells that remain in the bloodstream waiting for the same pathogen to come again.
Next time response is faster and without symptoms

10. Passive Immunity
When antibodies are transferred from mother to unborn baby through the placenta.
From mother to baby through the breast milk.
Injecting the body with antibodies

11. Activity Immunity
Obtained naturally when a person is exposed to the pathogen.
If the person encounters the same virus at a later date, they are immune to it.
Vaccine is a weakened or dead pathogen that is injected into the body to cause an immune response.

12. HOW ANTIBIOTICS WORK