why do we need water for body digestion?

Question

regarding enzymes etc...

Answer 1

In many stages of the digestive system, organs form special enzymes to break down the food into the molecules our bodies need. These special chemicals need to be "carried" to the alimentary canal from the organs that produce them; water is used. So, a large part of saliva is water (the enzyme in saliva is amylase). The stomach releases pepsin (an enzyme to break down protein) with water; the bile salts (formed in the liver and stored in the gall bladder) contain water, and the pancreas, which makes lipases (to break down fats), proteases (to break down proteins) and several other enzymes, releases the enzymes to the small intestine with water via a duct.
By the way, the enzymes are often released in a non-functioning form, that needs to be converted to an active form in the digestive system, but this is usually achieved by a protease.

Answer 2

A physician would give a better answer, the only liquids which people consume (deliberately) in significant quantities are water, ethyl alcohol and various oils. Water and alcohol are absorbed on a time scale of seconds to minutes through the mouth, stomach and digestive tract. The oils are huge molecules, so I'd guess like any other greasy food they get absorbed in the upper digestive tract. Some of them, perhaps the longest and most nonpolar, are not absorbed at all --- cf. the old-time remedy of mineral oil for constipation --- so there should be some average time-before-what's-left-is-excreted such as you're looking for, and my (wild) guess is that it would not differ substantially from that for food.
You can define an average lifetime in the body for alcohol, since the natural level is zero. Rough guidelines are widespread in the context of drunk driving laws. But this is not really possible for water. One's body is normally full up to the brim with water, and there's no way for the body to distinguish between water molecules recently absorbed and molecules that've been moping around since the Beatles split up. Thus the water entering the toilet bowl after the pit stop is not in general the same water as was in the big coke.
If you were to consider for water just the average time between drinking and peeing, it would seem to depend strongly on how well hydrated the body was before the drink, and how much was drunk. During sustained heavy
exertion in the sun and dry air one can easily drink a pint of water an hour without peeing at all. On the other hand, if one is willing to drink enough water fast enough, so as to establish a high excess of body water one can pee 8 ounces 15 minutes or less after drinking 8 ounces.

Answer 3

Water is needed

1. To dissolve the reactants and products - reactions take place in an aqueous enironment.

2. chemical digestion involves hydrolysis of large molecules into simple ones. Hydrolysis uses water as a reactant. eg starch + water ---> Glucose

3. The products of digestion diffuse from the gut into the blood vessels in aqueous solution

4. Water serves to activate the hydrolytic enzymes

Answer 4

Water activates the enzymes. It dissolves them allowing them to release their unique and specific properties relative to digestion of certain foods.

Actually and factually digestion starts in the mouth with a substance called pytalin. I think that's the name of the disgestive juice. ptyalin: a digestive enzyme found in saliva that begins the digestion of starches in the mouth