Explain how both the digestive system and the urinary system work to conserve water in the human body.

Everything that we eat and drink contains some percentage of water. So, to start, you have to know that the human body has receptors which estimate if we have enough water in our blood and cells in general. From these receptors, the information travels through the neurons to the part of the brain that is responsible for activation of different responses. 

The digestive system is important because in its lower parts, liquids are absorbed and inserted in the bloodstream. Then through the bloodstream, they travel to all parts of the body and are absorbed by cells as needed. When blood passes through the body, it gets to the kidneys where water and electrolytes are filtered, reabsorbed if needed and excreted through the urine. 

Now, if the brain has a signal that the body has a lack of liquids, it activates hormones which influence the bloodstream in both the digestive and the urinary system. In this case, the digestive system will absorb more liquids from food because the hormones will make the blood vessels in the digestive area larger, and on the other hand, we will produce less urine because the kidneys will get an assignment from the brain to filter liquids, but to reabsorb them again as much as possible. 

Not sure what you mean by this question

That would be a working theory.