Why shouldn't you laugh loudly when eating?

Both the air inhaled by the nose and the food chewed will pass through the pharynx and then go their separate ways. Air will enter the trachea and food will enter the esophagus (the trachea is located in front of the esophagus), which is determined by the epiglottic cartilage below the throat. When we inhale, the epiglottic cartilage will stay still and let air enter the trachea; When we swallow, on the one hand, the soft palate will extend backwards, preventing food from entering the nasal cavity; On the other hand, when the larynx rises, epiglottic cartilage covers the trachea and larynx like a door, so that food can enter the esophagus. Therefore, people joke when eating, and when swallowing, epiglottis can't cover the larynx and make food enter the trachea, causing severe cough.

So the answer is: when food enters the digestive tract through the esophagus, epiglottic cartilage below the throat covers the trachea and larynx like a door, allowing food to enter the esophagus.