Fill in the Blanks Digestive System Online version exercise by Aitor Sanjuan Manzano 1 The is among the most important digestive organs and is located behind the stomach The is the heaviest and largest gland in the human body and is formed of four lobes . The hard and soft palates form the roof of the and the pour their secretions into the during the oral phase of digestion . At the , the diameter of the GI tract increases to form a hollow sac - like structure made of three layers of smooth muscle . These muscles are arranged in longitudinal , diagonal and circular layers . The is among the most important digestive organs and is located behind the . It secretes a large number of enzymes , involved in the digestion of carbohydrates , fats , and proteins .
New game