Fill in the Blank QuestionFill in the blank question.Each main (primary) bronchus branches into bronchi.

The correct answer to fill in the blank is secondary bronchi.

Explanation:

The human respiratory system includes the trachea, which divides into the left and right main (primary) bronchi. Each primary bronchus further divides into secondary bronchi, which are also known as lobar bronchi. The number of secondary bronchi corresponds to the number of lobes in the lungs; the right lung has three lobes and the left lung has two lobes, resulting in three right secondary bronchi and two left secondary bronchi. This branching structure allows for efficient distribution of air throughout the lung tissue, maximizing gas exchange in the alveoli. Therefore, each main bronchus branches into secondary bronchi as part of the hierarchical structure of the bronchial tree in the respiratory system.