I'm guessing Liver.
If it was in the stomach, we wouldn't get belly aches. If it were in the large intestine, we wouldn't poop. So that's my guess.
Answer:
The entry of food into the stomach.
Explanation:
Gastric secretion is triggered by the act of eating which is called as reflex phase and the entry of food into the stomach called a gastric phase. The entry of the food particles into the small intestine also helps to control the secretion of gastric called an intestinal phase.
The secreted fluid in the small intestine contains some ions, acids, etc such as pepsinogen, intrinsic factor, bicarbonate, hydrochloric acid, and mucus. The reflex phase or cephalic phase helps to stimulate parasympathetic neurons that release acetylcholine chemical, then it produces the higher secretion of gastric juice.
You can't have a carrier with a dominant pedigree because other wise than individual or organism would be afflicted by the gene and render them incapable of being a carrier. A carrier is an individual/organism that has a normal phenotype (meaning it is not afflicted by said gene) but is carrying the gene that could cause disease or whatever the affect may be. In this case the gene would have to be homozygous recessive to be expressed. Hopefully this helps!