An athlete's body must regulate water, salts, and glucose during exercise.
In which specific part of the nephron does the selective reabsorption of glucose normally take place?
During a long-distance run, an athlete loses a large volume of water through sweat.
State how the concentration of ADH in the blood changes in response to this dehydration.
Describe the effect of this change on the kidneys and the resulting urine.
The table below shows information about three types of sports drinks:
| Sports drink | Solute concentration relative to blood | Carbohydrate mass per 100textmL100\\text{ mL}100textmL (g) | Speed of absorption |
|---|---|---|---|
| Hypotonic | Lower | <3<3<3 | Very fast |
| Isotonic | Same | 4−84-84−8 | Fast |
| Hypertonic | Higher | >8>8>8 | Slow |
An athlete drinks a hypertonic sports drink 45 minutes before starting a long-distance race. After completing the race, the athlete drinks an isotonic sports drink.
Explain the biological reasons behind the athlete's choice and timing of these drinks.