Immune+System+-+RJ

PATHOGENS 1. What is a pathogen? Collective bacteria and viruses

2. What are the body's three lines of defense against pathogens? Barriers: skin and mucous membranes of the body’s cavities First responders: phagocytic white blood cells, act to prevent infection Specific defenses: overcome an infection by killing the particular disease-causing agent that has entered the body. They also protect from cancer.

3. Write a one-paragraph summary of bacteria. Bacteria are a single celled prokaryote, which means they do not have a nucleus. Bacteria have three common shapes: a bacillus has a rod shape; a coccus has a spherical shape; spirillum is curved. Bacteria also have a cell wall that contains a very unique amino-disaccharide.

4. Write a one-paragraph summary of viruses. Viruses bridge that gap between the living and nonliving and are not composed of cells. Outside a host viruses are essentially chemicals that can be stored on a shelf. They replicate inside cells during a period of time they appear to be alive. They are obligate parasites and do not live independently. They also carry the genetic information needed to reproduce itself. Viruses gain entry into and are specific to a particular host cell because portions of the virus adhere in a lock-and-key manner with a receptor on the host ells outer surface. In large measure a virus relies on the host's enzyme and ribosome for its own reproduction.

5. What is an emerging virus? When a certain infectious disease in humans is transported from one location to another. Many are transmitted by vectors that are usually insects that carry disease from an infected individual to a healthy individual. Diseases spread by insects may require massive efforts to control the vector population and viruses can emerge through acquisitions of new surface antigens.

IMMUNE SYSTEM 6. What is an antibody? What do they do? Proteins. They are produced by the body to defend it from antigens.

7. What is B Cell? Lymphocyte that matures in the bone marrow. When stimulated by the presence of a specific antigen and gives rise to plasma cells that produce antibodies.

8. What is a Cytotoxic T Cell? A T-cell that attacks and kills antigen-bearing cells.

9. What is a Helper T Cell? A T cell that secretes cytokines that stimulate all kinds of immune system cells

10. What is an antigen? How does the body respond to an antigen? A foreign substance usually a protein of a polysaccharide that stimulates the immune system to produce antibodies and the body reacts to it so that the body remains free of disease.