1. Defense Against Infectious Disease Megan Harris IB Bio 6 June 2008 Megan Harris IB Bio 6 June 2008

2. Explain how skin and the mucous membrane act as barriers. The skin and mucous membranes counter pathogens with chemical defenses. In humans secretions from sweat glands give the sin a pH ranging from 3 to 5. Mucus, the fluid secreted by cells, also traps microbes and other particles the contact it. Microbes present in food or water, or those in swallowed mucus, must contend with the highly acidic environment.

3. Outline how phagocytic leucocytes ingest pathogens in blood and in body tissue. Cells of a tissue inured by physical damage or bacteria release a chemical signal such as histamine and prostaglandins. In response to the signals nearby capillaries dilate and become more permeable. Fluid and clotting elements move from the blood to the site, and clotting begins. Other factors released by various kinds of cells attract phagocytes form the blood. When the phagocytic cells arrive at the site they consume pathogens and cell debris and the tissue heals. Campbell Book: pg. 903 Fig. 43.5 Cells of a tissue inured by physical damage or bacteria release a chemical signal such as histamine and prostaglandins. In response to the signals nearby capillaries dilate and become more permeable. Fluid and clotting elements move from the blood to the site, and clotting begins. Other factors released by various kinds of cells attract phagocytes form the blood. When the phagocytic cells arrive at the site they consume pathogens and cell debris and the tissue heals. Campbell Book: pg. 903 Fig. 43.5

4. Explain the difference between antigens and antibodies. Antigens are foreign macromolecule that does not belong to the host organism and that elicits an immune response while an antibody is an antigen-bonding immunoglobulin that functions as the effector in an immune response.

5. Explain antibody production. Antibodies are produced by B cells. The term antigen is a contraction of antibody-generator.

6. Outline the effects of HIV on the immune system. People with AIDS are highly susceptible to opportunistic diseases, infections, cancers that take advantage of the immune system and cause the body’s system to collapse. Campbell Book: pg. 336 Fig. 18.7 People with AIDS are highly susceptible to opportunistic diseases, infections, cancers that take advantage of the immune system and cause the body’s system to collapse. Campbell Book: pg. 336 Fig. 18.7

7. Vocab!!! Immune System Antibody Antigen Immune System Antibody Antigen HIV Mucous membrane Phagocyte Leukocyte Host cell Virus