Food 2.0 L/day Saliva 1.5 L/day 1.5 L/day 消化道的液体平衡 Digestive secretions are mostly water 1 L/day Presented to lumen HCOS) with the average of small intestine 8.5 L/day amounts indicated here. Note that only Proximal Presented to colon: 100 ml are excreted by colon in feces. so the by colon 1.9 L/day mechanisms for water absorption are efficient (recall the kidneys primary role in water and Excreted osmotic homeostasis消化道的液体平衡 Digestive secretions are mostly water, with the average amounts indicated here. Note that only 100 ml are excreted in feces, so the mechanisms for water absorption are efficient (recall the kidneys’ primary role in water and osmotic homeostasis)