The organ in the human body responsible for digestion is the stomach. The stomach plays a crucial role in the digestive process, breaking down food into a semi-liquid form called chyme. It secretes gastric juices, including hydrochloric acid and digestive enzymes, that help break down proteins and kill harmful bacteria. The stomach's muscular walls contract to mix and churn food, facilitating digestion. After the stomach, chyme moves into the small intestine, where further digestion and nutrient absorption occur. The efficiency of the stomach is vital to overall health, providing the body with the necessary nutrients for energy and growth.