Beginning of Essay
The human, earthworm, and grasshopper digestive systems all have some similarities, as well as some differences. In the human digestive system, the process begins at the oral cavity (mouth). The mouth contains the teeth, tongue, and the salivary glands. The sa ....

Middle of Essay
.... The gastric glands secrete gastric juices. Hydrochloric acid is released which deactivates the salivary amylase, in turn stopping the chemical breakdown of starch into maltose. Pepsinogen, which is an inactive enzyme, will change to pepsin, an active enzyme, when mixed with hydrochloric acid. Pepsin breaks down proteins, forming chains of amino acids called polypeptides. Chyme, a mixture of churned food, mucus, and digestive enzymes, is formed and will pass through the pyloric sphincter into the small intestine. The small intestine is made up of three parts called the duodenum, jejunum, and ileum. All three parts aid in peristalsis. They also h ....