激素调节

Digestion involves the neuroendocrine system, with the brain monitoring and releasing digestive hormones at distinct periods throughout the process.

In the stomach, during the gastric phase, when proteins are detected, glands release two hormones, gastrin and histamine, which stimulate the production of hydrochloric acid and increase gastric juices that break down food into chyme.

The arrival of chyme in the duodenum causes the release of several hormones, which shut down the digestive process in the stomach and will begin pacing the movement of chyme through the rest of the system.

For instance, gastric inhibitory peptide, or GIP, slows stomach churning. Secretin and cholecystokinin, or CCK, then induce the sphincter between the stomach and duodenum to close, limiting the release of chyme.

Secretin also inhibits gastric juice production and stimulates the release of bicarbonates from the pancreas to neutralize the acidity of the chyme, and CCK stimulates digestive enzymes from the pancreas and bile from the gallbladder.

Lastly, peptide YY is a hormone released by the ileum, the end of the small intestine, and the colon. It slows the movement of chyme into the colon so that water and electrolytes can be readily absorbed. Peptide YY is also an I'm full signal sent to the brain to halt the eating process.