Definition: Phyllobranchial is a medical term that refers to a type of organ or tissue located in the upper part of the gastrointestinal tract. This area is known as the phyllobranchial region and is responsible for producing digestive enzymes such as amylase, proteolytic enzymes like pepsin, and lipases. The phyllobranchial region plays an important role in the digestion process by breaking down food into smaller pieces that can be absorbed more easily by the small intestine.