1. The polar bear is immense. However, it has an elongated, tapered neck and head. Contrast this body feature with the feature of a bicycle helmet. Discuss the impact on energy expenditure during land and water based movement. What features enable them to be more efficient in marine rather than terrestrial activity?
  2. The polar bear is truly evolving into, or can already be categorized as, a marine animal. Describe the muscle adaptations of marine mammals compared to land-based mammals.
  3. Energy turnover in skeletal muscle is a direct function of work performed. Oxygen uptake and power are linearly related. Arterial O2 content rather than tension is critical for regulation. Explain the role of hemoglobin in O2 content and possible adaptations by the polar bear.
  4. Considering their diet, what are the polar bearís fuels during exercise? How does the fuel affect their physical performance? Consider their frequency, intensity, duration, and type of physical activity.
  5. Describe activities that a human would have do to equate to the physical activity level (kcal.kg-1. day-1) of a polar bear.
  6. When diving, specific physiological responses are noted. Identify them. There appears to be no O2 conservation. What physiological attributes allow the polar bear to dive for periods that they do, especially in contrast to humansí abilities (approx. 1 minute, 5 meters)?
  7. The arctic environment is typically viewed as cold and pristine. However, many pollutants have been identified in the polar bearís food chain. Since the polar bear is at the top of the food chain, how have the contaminants affected them?
  8. For many species, an important adaptation during periods when food is unavailable is a reliance on previously accrued body-lipid stores for metabolizable energy. Polar bears undertake some of the most extreme fasts known for any mammal and have evolved impressive metabolic and morphological adaptations to fasting. The extreme variability in feeding regimen of polar bears also makes them an excellent model for investigating the mechanisms by which large mammals realize economies in nutrient expenditures during fasting. Some of the potential benefits to be gained from research include: 1) new insights into the physiological and morphological means that mammals use to conserve energy while fasting; 2) deeper understanding of lipid metabolism in carnivores, a major physiological constraint on survival and reproduction in this group; 3) determination of the fate of organochlorine contaminants and their metabolites in the tissues. The consequences of organochlorine contaminant kinetics during extended fasting are essentially unknown for any mammal. 4) development of allometric models of foraging tactics for large carnivores; 5) development of a model of the parental investment strategies of polar bears through continuing investigations into their breeding system and lactational energetics. During dormancy, the polar bear is better described as "fasting" rather than "starving": explain the metabolic differences.
  9. This species, Ursus, have brown fat (may also be in human infants but never fully substantiated). What unique metabolic properties does brown fat have?
  10. The chloride ion is important to acid-base balance and oxygenation of the polar bear. Describe its physiological roles.
  11. Explain the thermoregulatory adaptations of the polar bear. Although they are referred to as hibernators, they maintain their body temperature within a few degrees and so are not true hibernators. How do they maintain their body temperature during dormancy? What specific role might protein metabolism play?
  12. Decreased mechanical use of the skeleton results in osteoporosis. Are there unique metabolic adaptations of dormant polar bears to protect them against osteoporosis?
  13. When polar bears are in torpor, they lose very little lean body mass (LBM). Explain the exquisite metabolic adaptations that allow them to maintain LBM.
  14. Explain the unique composition of the polar bearís lactating milk. How does the sow maintain water balance?
  15. The polar bear has distinctive seasonal changes in hormones. Specifically address thyroid hormone (and various subtypes), opioids, and anabolic steroid hormones.
  16. Explain renal function of the polar bear during dormancy. How do they handle nitrogenous waste?