When shooting at deer with bow and arrow, aim for the heart regions. If the deer "jumps the string" by dropping sharply before bounding away, the arrow will still the lungs.
The problem with that is that if the deer is 10 yards or less and you are above 20 feet in the tree, then you are more than likely going to just get one lung if you do that. When a deer is in close like that you really need to aim a little high at the bottom of the top third of the deer. IMO If a deer is out further then by all means aim lower. I usually aim at the top of the bottom third of the deer when they are 20+ yards