Question

How is food prevented from going into the lungs while swallowing?

Answer 1

By the presence of a flap like structure called epiglottis which prevents the entry of food in wind pipe.

Answer 2

When we swallow food, it goes into the food pipe. To prevent food from entering the lungs, a flap called the epiglottis closes the lung pipe and thus, food doesn't enter your lungs.