This slit is the glottis and allows air to pass from the mouth into the lungs. Make a longitudinal incision through the body wall of the frog on the ventral surface. Make two transverse slits at the top and bottom of the cut. Fold the body wall back to examine the digestive organs. The stomach is a whitish, crescent-shaped structure which is connected with the mouth by the esophagus.
Food enters the mouth, passes into the esophagus, and then into the stomach where digestion begins.
The pyloric constriction at the posterior end of the stomach separates the stomach form the small intestine. That part of the small intestine immediately following the stomach is the duodenum. The duodenum forms a loop which passes upward under the liver and is continuous with the highly coiled ileum. Near the posterior part of the digestive tract, the intestine is enlarged to form the large intestine . Enzymes bring about digestion.