What is the position and function of the cartilage in the lungs?

Bronchus/bronchiole. The wind pipe or trachea branches of into left and right bronchus, they further divide into smaller bronchioles. These structures are made up of cartilage or soft bone and merely they act as a conduit for exchange of gases.
Support & structure. Your large central airways must conduct air to the smaller airways where gas exchange takes place. Without cartilage, there are wide swings of pressure in the chest that would otherwise collapse your trachea and bronchi. The cartilage serves to give some rigidity to airway walls so they stay open. People who lose the cartilage have tracheo- or bronchomalacia. It can be very serious, and debiliting.