Final answer:
The GI tract is a long tube extending from the mouth to the anus, measuring about 9 meters in adults, and includes both the upper (mouth to stomach) and lower (small and large intestines) divisions.
Step-by-step explanation:
The Gastrointestinal (GI) tract, also known as the digestive tract, is a crucial part of the human digestive system. It is a continuous tube approximately 9 meters (30 feet) long in adults and connects the mouth to the anus. The GI tract includes the upper gastrointestinal tract—comprising the mouth, pharynx, esophagus, and stomach—and the lower gastrointestinal tract—which includes the small and large intestines. The small intestine is notable for being about 4.6 to 6.9 meters long, depending on gender, and is where most chemical digestion and nutrient absorption occur. The large intestine, which averages about 1.5 meters in length, is responsible for water and salt absorption and preparing waste for elimination.