Physiology of the Gastrointestinal Tract Including Splanchnic Blood Flow and Tonometry

The primary functions of the gastrointestinal (GI) system are the digestion/absorption of nutrients and the elimination of waste material (Table 1). A 70-kg adult consumes approximately 800 to 1000 g of food and 1200 to 1500mL of water per day, while excreting approximately 50 g of undigested material and 100mL of water per day.