Chief cells are a vital part of the digestive and skeletal systems of the human body. They are found in the stomach and in the parathyroid. They secrete substances necessary for certain biological functions.
Gastric chief cells, those found in the stomach, secrete pepsinogen and chymosin to help digest proteins and break them into amino acid chains. Pepsinogen is a zymogen that converts into pepsin once it meets the acidic environment of the stomach. The pepsin then breaks proteins down into smaller amino acid chains that the body can absorb and utilize to repair cells and muscles.
Parathyroid chief cells produce and secrete parathyroid hormone to increase the body's calcium levels. Without this hormone, the body's calcium levels could drop and the bones could become brittle.