1. The Immune System (for dummies)
By Linh D. and Thy V.

2. a quick breakdown of what goes on in your body.

4. immune system?
The immune system is a network of organs, tissues, and cells that work together to defend the body against attacks by “foreign” invaders
Foreign invaders include:
Bacteria (Streptococci)
Viruses (Herpes)
Fungus (Candida)
Parasites (Plasmodium)
Antigen= pathogen that illicit (a) specific antibody(ies)

5. LYMPHOCYTES B-cells: Helper T-cells: -are later copied as memory cells
-Lymphocytes are produced by the spleen and other lymph nodes in the body. Lymphocytes are transported around the body via lymph and are the main men of the immune system. This “circulation” is referred to as the Lymphatic System.
B-cells:
-are later copied as memory cells
-copies plasma cells which release antibodies
-are activated by helper T-cells
Helper T-cells:
-activate B-cells
-copy into memory Helper T-cells
-stimulates Cytotoxic T- cells
Cytotoxic T-cells:
-attaches to target cell
-injects perforin into target cell & BOOM! Infected cells and cancer cells blow up.

6. A vertebrate’s defense?
3 Lines of Defense:
Skin and mucous membranes.
White blood cells and the inflammatory response
Lymphocytes and antibodies.
Passive Immunity:
Transfer of Antibodies from one organism to another. (Pregnant woman/fetus)
Active Immunity:
This is the 3rd line of defense, basically.
Humoral Immunity:
Bacteria -> Macrophage -> Helper T-Cell -> B-cell -> Plasma Cell->Antibody = Antigen becomes prey to phagocyte.
Defends against extrecellular pathogens.
Cell-Mediated Immunity:
Cytotoxic T-cells activates-> binds to target cell and releases perforin-> deflated cell, destroyed antigen.
Defends against intracellular pathogens

7. What about cancer? The breakdown.
Normal cells turns into cancer cells
Antigens on surface change
Cell sheds proteins into the circ. System (shed proteins are often tumor antigens)
Shed antigens prompt for arrival of cytotoxic T-cell
Cytotoxic T-cell latches on and injects perforin
The body is constantly under immune system surveillance to catch and destroy malignant growth. When the immune system is down or overwhelmed, tumors develop.

8. HIV/AIDS? Another breakdown
You have obtained HIV through unprotected sex with an infected partner
The virus fuses with your helper T-cells cell membrane
It injects its viral proteins and RNA
Reverse transcriptase occurs and DNA is formed
Viral DNA is incorporated with T-cell DNA as a provirus
Transcription/Translation occurs and viral parts are synthesized
Parts are assembled
New HIV viruses bud from the T-cell
This continues until the T-cell dies

9. What does HIV/AIDS do to your immune system?
Remember that the HIV virus basically destroys your helper T-cells.
Without any helper T-cells, B-cells, and memory cells, Cytotoxic cells can’t be activated and antibodies can’t be made.
This causes the immune system’s defense to drop greatly and…
You become greatly vulnerable to future infections
Drugs and medications only slow down the effects of HIV/AIDS, but can never stop it.
Today, there are no vaccines available to prevent HIV/AIDS.
In other words…

11. What are vaccinations?
Vaccinations are strains of weakened invaders, or pieces of the invaders.
These strains are injected into the blood stream to be recognized by the immune system.
The immune system creates memory cells for the particular invader…
That way, if a vaccinated person were to encounter the corresponding infection in the future…
The immune system’s response will be quicker and the person will experience less symptoms.

12. An invertebrate’s defense?
-Invertebrates are protected by physical and chemical barriers and cell based defenses.
Insects use their exoskeleton as their 1st line of defense.
Hemocytes (immune cells) circulate via hemolymph (insect equivalent of blood).
-Some hemocytes carry out phagocytosis (ingestion of bacteria or other material by phagocytes)
-Some trigger chemicals that kill microbes and multicellular parasites
-Some secrete antimicrobial peptides which inactivate/kill fungi and bacteria by disrupting their plasma membranes.