Stomach

Stomach sits under the ribs on the left side like a letter J. When we swallow, food travels down the esophagus and enters the stomach through a one-way door called the lower esophageal sphincter. The stomach can stretch to hold a large meal, then shrink back down as it empties.

Its walls contain three layers of muscle that squeeze in gentle waves called peristalsis. These motions stir food with gastric juice to form a creamy mixture named chyme. The juice includes hydrochloric acid to unfold proteins and enzymes like pepsin to cut them into smaller pieces. Mucus coats the lining so the acid does not harm the tissue.

Glands in the stomach also release hormones. Ghrelin reminds the brain when the stomach is empty, while gastrin signals the cells to make more acid when food arrives. When chyme is ready, the pyloric sphincter at the bottom opens a little at a time so the small intestine can handle each portion.

The stomach works closely with other organs. The pancreas adds enzymes, and the liver sends bile once the chyme reaches the duodenum. If food moves too quickly, we may feel cramps, and if it lingers too long, we may feel bloated. Balanced meals with fiber, protein, and water help the stomach move steadily.

Taking care of the stomach means eating slowly, avoiding large amounts of greasy or spicy foods when they cause discomfort, and washing hands to keep germs away. Doctors can use endoscopy to look at the lining, test for the bacterium Helicobacter pylori, or prescribe medicine that lowers acid if needed.