The human organ primarily responsible for digestion is the stomach. After food is chewed and swallowed, it travels down the esophagus to the stomach, where the digestion process continues. The stomach secretes gastric juices, containing hydrochloric acid and digestive enzymes, to break down food further. This acidic environment helps to kill bacteria and activate enzymes required for digestion. The stomach's muscular walls churn food, mixing it with these enzymes to form a semi-liquid substance called chyme. From the stomach, chyme moves into the small intestine, where the majority of nutrient absorption occurs, showcasing the stomach's crucial role in the digestive system.