Break down organic nutrients so that they can be absorbed into the body organic nutrients can be carbohydrates, proteins, fats, water, vitamins, and minerals. Mouth salivary glands esophagus stomach stomach liver gallbladder pancreas small intestine large intestine rectum secretion: stores and concentrates undigested material and absorbs salt and water, site where the defecation reflex is triggered. The stomach function stomach liquefies, mixes, and stores each bolus of food from the meal. The stomach secretes a variety of substances. Mucus: secreted by cells in the body and antrum of the stomach, protects the linings of the stomach from the extremely acid environment that is produced by hcl. Hcl: secreted by cells in the stomach body, begins to denature the complex proteins and connective tissue molecules found in meat, kills bacteria. Cells in the body of the stomach produce pepsinogen: when converted to its active form pepsin by the hcl, it begins to digest large protein molecules.