Final answer:
Prolonged exercise in a hot, humid environment can lead to severe dehydration, resulting in symptoms such as extreme thirst and a dry tongue.
Step-by-step explanation:
When exercising in a hot and humid environment, prolonged dehydration can occur. Dehydration refers to the loss of water from the body without adequate replacement. Some of the effects of severe dehydration include excessive water loss due to sweating, increased concentration of extracellular fluid, extreme thirst, hot and dry body, and dry tongue.