The gastrointestinal tract, also called the digestive tract or alimentary canal, is a series of hollow organs interconnected in a long tube. It is a part of the digestive system, which is a complex organ system located throughout most of the body. The gastrointestinal tract is located in the head, neck, thoracic and abdominal cavities, as well as in the pelvis.

Overall, the gastrointestinal tract provides passage and storage of the digested food. It is responsible for mechanical and chemical food procession, absorption of nutrients and water, and excretion of the undigested remains. The gastrointestinal tract starts with the oral fissure and mouth and ends with the anal canal and anus. The length of a human digestive tract varies, but it usually is about 26 to 33 feet (8 to 10 meters) long and includes the following structures:

• Oral cavity - has two parts:
  • Oral vestibule - formed by the lips, cheeks, gums and teeth;
  • Oral cavity proper - composed of the palate, tongue and salivary glands;
• Pharynx - made of three portions:
  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• Esophagus (Read more!)
• Stomach (Read more!)
• Small intestine (Read more!) - it consists of the following three portions:
  • Duodenum
  • Jejunum
  • Ileum
• Large intestine (Read more!) - subdivided into the following parts:
  • Cecum and vermiform appendix
  • Colon
    • Ascending colon
    • Transverse colon
    • Descending colon
    • Sigmoid colon
  • Rectum
  • Anal canal

Accessory organs of digestive system

In addition to the gastrointestinal tract, the digestive system also includes several accessory organs (mostly various glands) that aid in the digestion process. They are located along the length of the gastrointestinal tract, mainly within the abdominal cavity. The accessory organs of the digestive system include the following structures:

• Salivary glands
  • Minor salivary glands
  • Major salivary glands
    • Submandibular salivary glands
    • Sublingual salivary glands
    • Parotid salivary glands
• Liver (Read more!)
• Pancreas (Read more!)
• Gallbladder (Read more!)
• Biliary tree

The accessory organs produce various enzymes and, therefore, help to break down the food.