I was listening to the zoology Digestion class, and this is when the teacher put the following question on us:

Question

The Question is simple:
When we eat food, it goes into the stomach through the oesophagous. The food is made acidic, and many enzymes (proteins) are secreted, in order ro digest the food.
The food reaches the intestine, where many nutrients are absorbed. Including some of the secretions made in the stomach. ( Not all are absorbed, since many of the enzymes are macro-molecules. So, they wouldnt be able to pass the absorbing membrane).
The tricky part is that Intestines also secrete (coupled with the secretions of Liver, Gall bladder, and pancreas, which join the main tract, after stomach).. So, the food (or whatever the material is called in the intestine) is rich with the body secreted enzymes (which are incidentally protein rich). Does the body absorb all these back?, and If yes, How?..
Why does the body need to secrete all those protein rich enzymes, when it can conserve straight away?..
The most important thing is- What happens to intestinal secretions?absorbed by Rectum?

Answer 1

I think that you answered part of the question yourself. All the secreted digestive enzymes , which are organic catalysts (chemically proteins), are composed of molecules too large to be absorbed into the circulatory system. It's OK, as long as we keep eating foods rich in protein the body will manufacture more
enzymes as needed. I believe that all of the excess enzymes and bile (which is not an enzyme) is simply egested through the anus as part of the fecal matter. The only material that is
absorbed into the blood form the large intestine (colon)
is water (water conservation here). The function of the rectum is waste storage,
nothing is absorbed there.
By way of definitions: chewed food in mouth prior to swallowing- Bolus.
Stomach contents- Chyme (low pH)
Small intestinal contents- Chyle (alkaline secretions raises pH)

Answer 2

Well, I'm non poopologist but here's a partial answer. It takes money to make money (only replace "energy" where it says "money"). Remember that digestive enzymes are.. enzymes. While the transcription and translation of that enzyme are costly, the enzyme can then catalyze the breakdown and release of energy sources 1000s of times. The pay back well outweighs that cost of production.

As for the non-proteinacous acids and secretions (bile salts, cholestorol, etc) my guess is that they just pass. Again, they're cheep compared to what they make available - especially if you've just had a nice NY strip... MAN I'M HUNGRY NOW.