Hormones and the gastrointestinal tract

The gastrointestinal tract is the largest endocrine organ in the body, with its component cells dispersed along its length rather than being clustered in glands. Gut peptides integrate gastrointestinal function by regulating the actions of the epithelium, muscles, and nerves, affect the growth and development of the gut and—as has emerged comparatively recently—they also have a major role in appetite control. There is little evidence that many gut peptides act as hormones in a classical endocrine fashion: many are autocrine, regulating the function of the cell secreting them, or paracrine, influencing the behaviour of neighbouring cells of different types....