The organ primarily responsible for digestion is the stomach. Located between the esophagus and the small intestine, the stomach plays a crucial role in breaking down food and facilitating digestion. It achieves this through the secretion of gastric juices, which contain hydrochloric acid and digestive enzymes that help to chemically break down food, particularly proteins. The muscular walls of the stomach also churn the food, mixing it with these digestive juices to create a semi-liquid substance known as chyme. This process prepares the food for further digestion in the small intestine, where nutrients are absorbed into the bloodstream.