What prevents the trachea and the bronchi from collapsing?

cbse
breathing

#1

(i) What prevents the trachea and the bronchi from collapsing?
(ii) Name the epithelium and the cells present in the walls of trachea, bronchi and bronchioles,


#2

(i) Cartilaginous rings are incomplete from behind which supports the walls of the trachea and the bronchi to prevent them from collapsing.
(ii) Pseudostratified ciliated columnar epithelium is rich in mucous secreting cells.