The parts of the respiratory system that divide into smaller and smaller tubes in a pattern resembling a tree are the bronchi and bronchioles.

Here's a breakdown:

* Trachea: The windpipe, which carries air from the throat to the lungs, divides into two main branches called bronchi.

* Bronchi: These two branches, one for each lung, further divide into smaller and smaller tubes called bronchioles.

* Bronchioles: These continue to branch out, eventually becoming microscopic tubes called terminal bronchioles.

This branching pattern, often referred to as the bronchial tree, is crucial for efficiently delivering air to the alveoli, tiny air sacs in the lungs where gas exchange occurs.