Immune+System+WB

PATHOGENS 1. What is a pathogen? 2. What are the body's three lines of defense against pathogens? 3. Write a one paragraph summary of bacteria. 4. Write a one paragraph summary of viruses. 5. What is an emerging virus? IMMUNE SYSTEM 6. What is an antibody? What do they do? 7. What is B Cell? 8. What is a Cytotoxic T Cell? 9. What is a Helper T Cell? 10. What is an antigen? How does the body respond to an antigen?

1. A pathogen is an infectious disease that comes from viruses and bacteria. 2. The first line of defense is a barrier, like skin or mucous. The second line of defense are the first responder, like the white blood cells. 3. Bacteria are single-celled prokaryotes without a nucleus. There are three shapes of bacteria, which include bacillus, coccus, and spirillum. Many bacteria are surrounded by a sticky capsule, which allows them to stick to parts of the body. Bacteria contain plasmids, which connect antibodies and genes. Fimbriae on the outer surface of the bacteria allow it to attach itself to surfaces, and also permit movement. 4. 5. An emerging virus is a virus that moves from one place to another place, where it has never been before. SARS is an example of an emerging virus. 6. An antibody is a protein produced in response to an antigen. Antibodies combine with antigens. 7. B cells produce plasma cells and memory cells. 8. A Cytoxic T cell kills virus-infected cells. They also kill cancer cells. 9. A helper T cell regulates immunity. 10. An antigen is substance that causes the body to produce antibodies.