Over a tropical land region
Hope this helps :)
It seems that you have missed the necessary options to answer this question, but anyway here is the answer. Since the person spends several days in a hot, dry desert environment with little water available to drink, the kidneys' function during this time is that, the amount of urine produced is decreased in order to maintain the proper amount of water in the bloodstream. Hope this answer helps.
The term that is used to describe a chemical reaction in which water is produced or gained I believe is Dehydration Synthesis.
It has a neurotic....which on hydric pressure....releases.....and paralise the prey......and thus able to eat or defense as well !