These results were obtained by measuring the body temperature of people exercising on a hot and humid day.
What mechanism could result in the changes seen during the rest periods?
Correct Answer: \( \boxed{\mathbf{C}} \)
During the rest periods, body temperature falls because vasodilation increases blood flow to the skin, allowing more heat to be lost to the surroundings. This cooling mechanism helps regulate body temperature after exercise, especially in hot conditions.
How is the regulation of blood glucose levels carried out by hormones released from the pancreas?
| Option | Deviation of blood glucose level from normal | Hormone secreted by pancreas | Effect |
|---|---|---|---|
| A | higher | glucagon | muscles break down glycogen into glucose |
| B | higher | insulin | small intestine slows glucose absorption |
| C | lower | glucagon | liver converts glycogen to glucose |
| D | lower | insulin | kidney reabsorbs more glucose |
The dark areas in the PET/CT scans show increased activity of brown adipose tissue at 2 °C. How does brown adipose tissue help regulate body temperature?
Correct Answer: \( \boxed{\mathbf{D}} \)
Brown adipose tissue (brown fat) carries out non-shivering thermogenesis. It contains many mitochondria with uncoupling protein 1 (UCP1), which allows energy from the oxidation of fatty acids to be released as heat instead of being used to produce ATP. This helps maintain body temperature in cold conditions.
