The structure that prevents food from entering the lungs is called the epiglottis. This flap-like cartilage is located at the base of the tongue and covers the entrance of the larynx during swallowing. When a person eats or drinks, the epiglottis folds down to seal off the trachea, directing food and liquids into the esophagus instead. This mechanism is vital for preventing aspiration, which can lead to choking or respiratory infections. The epiglottis plays a crucial role in maintaining the separation between the digestive and respiratory systems, ensuring that the airway remains clear during the swallowing process.