What are the multiple guesses?
One function is to help regulate digestion.
The most immediate thing you can do is move the player you suspect is in heat stroke (usually they are flushed, and dry, because the heat has compromised heat regulation. They are also more than likely to be down), to a cool, well ventilated, Air conditioned area. You need to bring down their body temperature as quickly as possible. At least if this unavailable move him into a car, blast the A/C, and have a towel soaked with water placed on him.
