hat prevents food and water from entering the trachea and the lungs. It stays open during breathing, allowing air into the larynx. During

The structure that prevents food and water from entering the trachea and the lungs is the epiglottis. Here are the steps explaining how it works:

1. The epiglottis is a flap of tissue located at the base of the tongue, in front of the entrance to the larynx (voice box).

2. When you are not eating or drinking, the epiglottis stays open to allow air to pass into the larynx and then the trachea (windpipe) for respiration.

3. When you swallow, the action of swallowing causes the epiglottis to close over the opening of the larynx. This prevents food and water from entering the trachea and the lungs, directing it instead into the esophagus (food pipe) and then the stomach.

4. Once the act of swallowing is completed, the epiglottis opens again to allow for breathing.

So, the epiglottis plays a crucial role in ensuring that the processes of eating/drinking and breathing do not interfere with each other.