Gosh, I think many things fit this description but the one that comes to mind is the circulatory system. I begins with large vessels (arteries) and continues to branch into smaller and smaller tubes (capillaries) like the branches of a tree.
bronchi
it divides into two bronchis and the the aveioli
Bronchioles
bonchi
bronchioles
it divides into two bronchis and the the aveioli
it divides into two bronchis and the the aveioli
Because branching into smaller and smaller tubes increases the surface area that the lings have to enable them to absorb oxygen.
By I only ought be able skills and tomorrow morning to be able skills
The bronchial tubes (or bronchi) are the large tubular structures within the lungs. These carry air into the lungs from the trachea. They branch into smaller tubes called bronchioles, and then to the smallest tubes that contain the alveoli (air sacs) of the lungs.
Bronchioles
Bronchi are the two tubes that branch off into each lung.