Question

(a)The two openings of pharynx, one leading to trachea and other to oesophagus, lie very close
to each other. Yet food we swallow normally does not enter our trachea. Why?
(b) What is the role of hydrochloric acid in human digestive system?

Answer 1

• This is because the entrance to the trachea is guarded by a flap called the epiglottis. When the bolus reaches the junction of the pharynx then the larynx or the voice box which is located at the entrance of the trachea is pulled upward to bring it close to the back of the tongue and then the flap closes the opening of the trachea.

• The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins. The acidic gastric juice also kills bacteria.