Information on the STomach

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Dear Joel,

The stomach dissolves things you eat with a combination of enzymes and hydrochloric acid (HCl). The acidity of HCl (typically pH is around 1 in the stomach) is often enough to get things started. The enzyme pepsin, secreted by the "chief" cells of the stomach, is called a proteolytic enzyme because it chops up proteins (proteo- for protein, and lysis is cutting).
Check out this web site for a good overview to get you started: http://users.rcn.com/jkimball.ma.ultran ... ml#stomach

The stomach moves during digestion because it is made of smooth muscle, which responds to nerves in the autonomic nervous system (the part of the nervous system that is not consciously controlled - think "automatic") and to the hormone gastrin, which is released into the bloodstream by the stomach itself. Both stimulation by the parasympathetic division of the autonomic nervous system and the arrival of gastrin in blood vessels around the stomach tell the smooth muscles in the stomach to move, which churns the contents.

"Stomach lining" simply refers to the cells lining the inside of the stomach wall. The stomach lining is made up of parietal cells, "chief" cells, and mucus-secreting cells, each with their own functions. (Look at that web site I gave you to get an idea of what they do.)

Keep in mind that not a lot of absorption happens in the stomach. Most things you eat are absorbed in the small intestine. However, some analgesics like aspirin are absorbed through the stomach, which is why they work so fast.

I hope this helps you. Good luck!

Heather