What structure seals off the windpipe to prevent food from entering?

The epiglottis is a crucial structure that acts as a protective flap at the base of the tongue. Its primary function is to seal off the windpipe (trachea) during swallowing, which prevents food and liquids from entering the respiratory tract. When you swallow, the epiglottis folds down to cover the trachea, allowing food to pass into the esophagus instead. This mechanism is essential for ensuring that the airway remains clear and that aspirated food or liquid does not cause choking or respiratory complications.

In contrast, alveoli are the tiny air sacs in the lungs responsible for the exchange of oxygen and carbon dioxide. The trachea is the windpipe itself, a passageway for air, and is not responsible for sealing off during swallowing. The mediastinum is an anatomical region in the chest that contains the heart, major blood vessels, and other structures, but it does not play a role in preventing food from entering the airway. Each of these structures serves distinct functions in the respiratory or cardiovascular system, highlighting the specific role of the epiglottis in swallowing.