Here I will talk about the digestive system of my Kepler Bb humanoids.
The teeth are much stronger than bone(Strong enough that they can eat bones no problem). Other than that and all time tooth formation(so a loose adult tooth is no problem for them since another will grow in its place), they are pretty much human in the mouth.
Not much difference here besides length and time it takes for food to go down the esophagus.
This here is where it differs the most. There are actually 2 stomachs connected to each other but they each have different roles.
The first stomach is the one most likely to get infected and is where chemical and mechanical digestion take place.
The second stomach is less likely to get infected and is used as an antinausea defense. If the first stomach is too full, only a little bit of food goes to the second stomach. If the first stomach is infected, all the food goes to the second stomach. Here only chemical digestion takes place.
There is a sphincter that separates the 2 stomachs which I call the gastric sphincter. This is why food doesn't always go into the second stomach.
In the second stomach, once it gets full enough it starts pushing the partially digested food into the first stomach which then lets it through bit by bit into the intestines.
The liver, gall bladder, and pancreas are just like the esophagus in that there is little to no difference.
Here there are some differences. For 1, the small intestine has even more absorptive surface area than ours. Second, there are glands in the small intestine that secrete their own digestive juices. The large intestine has a longer appendix that isn't useless at all and won't burst simply from inflammation. So a humanoid can have appendicitis several times in its life without an appendicular rupture(rupture of the appendix). Other than that, the large intestine, rectum, and anus are just like ours except for size.
I will draw the whole digestive system in different states later but don't be surprised if it is a bad drawing. I am horrible at drawing the intestines.
Anyway, is it useful to have this gastric sphincter and second stomach as an antinausea defense and to have the second stomach push stored food into the first stomach instead of pushing it directly into the intestines?
Here are a few pictures of their digestive system(Liver, pancreas, and gall bladder not included):
You see how bad I am at drawing the intestines? None of these drawings are to scale.