Critical thinking
1. After learning that sweat evaporation results in loss of calories, an anatomy and physiology student enters a sauna to try to lose weight. He reasons that a liter (about a quart) of water weighs 1000 g, which is equivalent to 580,000 cal, or 580 kcal, of heat when lost as sweat. Therefore, instead of reducing his diet by 580 kcal/day, he believes that losing a liter of sweat every day in the sauna will cause him to lose about a pound of fat a week. Will this approach work? Explain.
2. Thyroid hormone increases the activity of the sodium-potassium pump. If a person produced excess amounts of thyroid hormone, how would basal metabolic rate, body weight, and body temperature be affected? How would the body attempt to compensate for the changes in body weight and temperature?
3. Why are athletes advised not to take alcohol before a race, especially in hot climate?
4. Who is better protected against extreme heat: a person in clothes or one without clothes?
5. In some diseases, an infection causes a high fever, resulting in a crisis state. Once body temperature begins to return to normal, the person is on the way to recovery. If you were looking for symptoms in a person who had just passed through the crisis state, would you look for dry, pale skin or flushed, wet skin? Explain.
6. What special problems would result from the loss of 50%of a person's functional skin surface? How might this person's environment be modified to compensate partially for such a loss?
7. A premature infant typically lacks subcutaneous adipose tissue. Also, the surface area of an infant's body is relatively large compared to its volume. How do these factors affect the ability of an infant to regulate its body temperature?
8. As a rule, a superficial partial-thickness burn is more painful than one involving deeper tissues. How would you explain this observation?
9. Which of the following would result in the more rapid absorption of a drug: a subcutaneous injection or an intradermal injection? Why?
10. What methods might be used to cool the skin of a child experiencing a high fever? For each method you list, identify the means by which it promotes heat loss—radiation, conduction, convection, or evaporation.
11. How would you explain to an athlete the importance of keeping the body hydrated when exercising in warm weather?
12. Everyone's skin contains about the same number of melanocytes even though people come in many different colors. How is this possible?
13. How is skin peeling after severe sunburn protective? How might a fever be protective?
14. Why would collagen and elastin added to skin creams be unlikely to penetrate the skin—as some advertisement simply they do?
15. Which of the following would result in the more rapid absorption of a drug: a subcutaneous injection or an intradermal injection? Why?