esophagus tube

The esophagus is an elastic tube, which measures about 25 centimeters long. Leads the food from the back of the throat to the stomach. But in the back of the throat is also the trachea, which allows air to enter and exit your body. When you swallow a ball of food and crushed or softened some liquid, a barb of a special fabric called epiglottis closes the opening in the trachea to ensure that the food enters the esophagus, rather than the trachea. 

If you've ever drunk a little too fast, you've started coughing and someone said that the drink "you'll be gone by the other side", which meant that person is the liquid you had come into the trachea by mistake . This happens when the epiglottis does not give you time to close, and you'll be coughing involuntarily (without thinking about it) to clear the trachea.