The number of secondary bronchi is five.
The human respiratory system features a branching network of airways that deliver air to the lungs. The trachea splits into two main bronchi, which then further divide into secondary (or lobar) bronchi. These secondary bronchi supply air to the lobes of the lungs.
- The right lung has three lobes (superior, middle, and inferior), so it has three secondary bronchi.
- The left lung has two lobes (superior and inferior), so it has two secondary bronchi.
As stated in the provided reference, the right main bronchus branches into 3 secondary bronchi (right upper lobe bronchus, right middle lobe bronchus, right lower lobe bronchus). Since there are two secondary bronchi on the left, the total is five.
Therefore, there are a total of five secondary bronchi: three in the right lung and two in the left lung.
