To better understand upper gastrointestinal bleeding, it helps to understand the anatomy of the esophagus and stomach.

The esophagus is a muscular tube that pushes food to the stomach. The stomach is a large pouch that receives food from a meal. The stomach slowly pushes the food into the small intestine, which absorbs nutrients from the food. The food passes through the small intestine and into the large intestine, which absorbs water from the food. The small intestine is about 18 feet (3.5 m) long and the large intestine is about 5 feet (1.5 m) long.

Gastrointestinal anatomy:

• Esophagus and stomach
• Intestines and other abdominal organs
• Blood vessels of the intestines
• Entire gastrointestinal tract