A relatively stable internal environment is essential for the survival of cells, which make up the body systems in humans. These body systems, in turn, work collectively to maintain the internal environment shared by all cells. This maintenance of a stable internal environment is called homeostasis. Homeostasis involves holding the chemical composition and physical state of the body within optimal ranges, responding to any changes that shift this internal environment from its set point. The following graph depicts changes that might occur during the maintenance of body temperature within a 24-hour period, as measured in the arms of a healthy human. The dotted line through the middie of the graph indicates the desired, or optimal, body temperature. Changes in body temperature during a 24-hour period, as measured in the arms Maximum survivable level Minimum survivable level The letters along the graph note different periods. Identify the perlods that each of the following statements describe. Check all that apply. B. G. A strong compensatory response returns body temperature to desirable levels. An external or internal factor starts to move body temperature away from the set point. Now, consider the following graph depicting the changes in body temperature that occur during the same day, measured in the brain rather than the arms. Now, consider the following graph depicting the changes in body temperature that occur during the same day, measured in the brain rather than the arms. Changes in body temperature during the same 24-hour period, as measured in the brain Maximum survivable level Minimum survivable level Compare the two graphs, whose axes are on the same scale. While the same basic trends occur in both parts of the body, they are pronounced in the arms. In addition, the brain appears to be tolerant of wide changes compared with the body temperature in the arms. In this example, body temperature is maintained in a dynamic steady state, meaning that, although body temperature compensatory physiological responses can help deviations from optimal levels, thereby keeping body temperature at a somewhat constant level.