Immune System: Overview of Innate and Adaptive Body Defenses
1. Name the three main lines of defense and give an example of each:
Line of Defense Example
Innate external defense (surface barriers) skin and mucous membranes
Innate internal defense cells and chemicals in body fluids
Adaptive defenses T and B cells
2. When the surface barriers (innate external defenses) are penetrated, what is the next line of defense? innate
internal defense
3. This defense mechanism (named in question 6) identifies enemies by recognizing markers unique to the
pathogens. When they are overwhelmed, they secrete chemical messengers to mobilize the adaptive
defenses.
4. B and T lymphocytes recognize pathogens by binding to them. What the lymphocyte recognizes is called
the antigenic determinant found on the antigen.
5. Specific B cells called plasma cells secrete antibodies, which bind to the antigens.
Humoral Versus Cellular Immunity
6. Humoral immunity is directed against pathogens in the extracellular fluid. This immunity involves B
lymphocytes.
7. Cellular immunity is directed against pathogens within the cells. This immunity involves T lymphocytes.
8. Which type of immunity involves antibodies? Humoral Immunity
9. Name three circumstances in which T cells would be activated against body cells:
1. a cell becomes cancerous
2. a cell is invaded by a virus
3. a cell has been transplanted from another individual
1. Name the three main lines of defense and give an example of each:
Line of Defense Example
Innate external defense (surface barriers) skin and mucous membranes
Innate internal defense cells and chemicals in body fluids
Adaptive defenses T and B cells
2. When the surface barriers (innate external defenses) are penetrated, what is the next line of defense? innate
internal defense
3. This defense mechanism (named in question 6) identifies enemies by recognizing markers unique to the
pathogens. When they are overwhelmed, they secrete chemical messengers to mobilize the adaptive
defenses.
4. B and T lymphocytes recognize pathogens by binding to them. What the lymphocyte recognizes is called
the antigenic determinant found on the antigen.
5. Specific B cells called plasma cells secrete antibodies, which bind to the antigens.
Humoral Versus Cellular Immunity
6. Humoral immunity is directed against pathogens in the extracellular fluid. This immunity involves B
lymphocytes.
7. Cellular immunity is directed against pathogens within the cells. This immunity involves T lymphocytes.
8. Which type of immunity involves antibodies? Humoral Immunity
9. Name three circumstances in which T cells would be activated against body cells:
1. a cell becomes cancerous
2. a cell is invaded by a virus
3. a cell has been transplanted from another individual
