Objectives:

• Use the resources on the world wide web to investigate the relationships between changes in tissues and specific diseases.
• Take a look at two examples of homeostasis which is the human body's ability to meet changing demands by making adjustments in specific physiological and metabolic activities.

Approach:

• I have selected four topics about which I have been curious to find out more. For each topic I will pose a question that extends beyond the information presented in the text. I will offer you some URLs where you can investigate additional information on each topic. You can use CUT and PASTE to bring information, including graphics, back to this web page to include in your answers in addition to the writing that you do. You do not have to do the questions in order. As is common on the web, there is always more that you can find to investigate beyond the suggestions I am providing for you.

Dr. Paul Tabor

OK, here are the questions:

1. The liver is an organ that has vital importance for the body. It is a dynamic filter for our blood among other things. When liver tissue is damaged, the tissue that grows back can be scar tissue and this is called cirrhosis. The scar tissue can not function to filter, infact it may act to inhibit blood flow in the liver. Is it possible to regenerate liver tissue to replace the cirrhosis? Is there a connection between the deficiency caused by the most common inherited form of liver disease and the damage to liver tissue? How can this disease be treated?

2. Tissues change as we age and no tissue shows this better that our skin (look at slide #21). What changes occur in our skin as we age (view the slide "Skin, Well Differentiated Squamous Cell Carcinoma - 4X)? Can we identify some factor that is responsible for the change in our skin tissue cells?

3. In many biology text books the discussion of homeostasis in humans usually includes the regulation of blood glucose levels by the liver's response to insulin and the production and storage of glycogen, and the regulation of body temperature by the physiological changes in the body directed via nerve impulses controlled by the hypothalamus. But, there are many other interesting processes that fall in the catagory of homeostasis. Do you think your body has a homeostatic response to loud noise to protect your hearing. After you have heard a rock band performance do you notice that your ears ring and you have a temporary hearing loss. Is this actually a homeostatic mechanism to save your hearing? What are the specific physiological adaptations your ears have made?

4. Another interesting homeostatic response is one that atheletes wish to optimized. It is the mechanism your body uses to increase the supply of oxygen to your muscle cells when you exercise, particularly when you go skiing in the mountains where the oxygen levels are lower because of altitiude. When the partial pressure of oxygen changes with altitude, the blood will have proportionally lower dissolved oxygen. How does the body respond to balance the concentration of oxygen in the blood? This mechanism increases the oxygen delivery capabilities of your body. But can the oxygen that is available be more efficiently extracted by the cells in the tissues where it is needed? A related response is the cardiovascular homeostasis associated with math anxiety. This web site gives the procedure for you to measure your own response to the stress of a test.