What is the relative responsibility of each part (stomach, small intestine, large intestine) in overall water absorption? My understanding is that the stomach absorbs some water, the small intesting absorbs some, and the large intestine absorbs or excretes water depending on whether the body is overhydrated or underhydrated. I’m looking to find out where the bulk of water is absorbed (a) from food, and (b) if you just guzzle a whole lot of water.
I think there is much more absorption in the large intestine relative to the others, so that the system can carry an easily transported liquid. I think the ability of the upper tract to absorb water relates more to the need to rapidly fix dehydration than it does to normal operation. Don’t remember any cites, tho.