The rectum and anus are the final stages of the digestive tract. The rectum is the last straight section of the large intestine before reaching the anus.The anus is the opening at the lower end of the digestive tract that controls the expulsion of feces. Read on to learn more about the rectum and anus, and their role in digestion.he rectum and anus are the final stages of the digestive tract. The rectum is the last straight section of the large intestine before reaching the anus.