The organ primarily responsible for digestion in the human body is the stomach. Once food passes through the esophagus, it enters the stomach, where it is mixed with gastric juices, containing hydrochloric acid and digestive enzymes. This process breaks down food into a semi-liquid substance called chyme, which is then gradually released into the small intestine. The stomach plays a significant role in the digestive process, contributing to both the mechanical and chemical breakdown of food before further digestion and absorption occur in the intestines. Overall, the stomach is vital for efficient digestion and nutrient absorption.