Pathogens+PK

__**PATHOGENS**__

1. What is a pathogen? - A pathogen is a virus or a bacteria. The word comes from a Greek word that means produce suffering.

2. What are the body's three lines of defense against pathogens? - The three lines of defense are skin and mucous membranes, chemical barriers, and resident bacteria. They are both physical and chemial that serve as the first line of defense.



3. Write a one paragraph summary of bacteria. - Bacteria are unicellular microorganisms that vary in shapes. The changes range from spheres, rods and spirals. Bacteria live in every habitat on Earth. The bacteria can be used in recycling processes, cheese and yogurt processes.

4. Write a one paragraph summary of viruses. - Viruses are a sub-microscopic infectious agents that are unable to grow or reproduce outside of a host cell. Each partical of the virus is made up of DNA or RNA. It is debatable on whether viruses are living or not. Vaccines can prevent viral infections through producing a lifelong immunity

5. What is an emerging virus? - Emerging viruses are newly discovered viruses, such as Ebola and bird flu.

__**IMMUNE SYSTEM**__

6. What is an antibody? What do they do? - Antibodies are proteins that are found in the blood or fluids in the vertebrae. They are a vital part of the immune system because they identify and neutralize foreign pathogen.

7. What is B Cell? - B Cells are lymphocytes that are very important to the immune system because they make antibodies against soluble antigens.



8. What is a Cytotoxic T Cell? - Cytotoxic T Cells are a type of lymphocytes which kill cells that are infected with viruses or other pathogens.

9. What is a Helper T Cell? - Helper T Cells are a type of lymphocytes that activate and direct other immune cells to kill infected host cells.

10. What is an antigen? How does the body respond to an antigen? - An antigen is a molecule that can stimulate an immune respone. The body responds by attacking the antigen, resulting in allergic symptoms.