I see it a bit like this photo. You eat your food, it is digested and afterwards it is disposed of. However, if no-one empties the garbage can it is not so good. My Mr. Swiss suffered from diverticulitis for a few years until the garbage can needed some repair work, although repairs meant removing the parts that were no longer working as smooth as they should be. It was quite painful. After an operation and removal of 28 cm of the colon, the garbage can was back in order. This was about 20 years ago and no more problems.