Special structures of the avian digestive tube

Question

Describe the special structures of the avian digestive tube and their relevant functions?

Answer 1

The digestive tube of birds consists of special structures, in this sequential order: the crop, the proventriculus and the gizzard. The crop consists of the function of temporary storage of ingested food and it is a much dilated region of the avian esophagus. The proventriculus is the chemical stomach of birds where food is mix with digestive enzymes. The gizzard is a muscular pouch which serves as a mechanical stomach where the food is ground to raise the exposure region of the food particles for the digestive enzymes to perform.