Most WHO departments have their own procedures for supporting research in priority areas-these vary from requesting letters of intent to issuing a call for proposals to commissioning research.
In humans and other mammals, the anatomical features of the respiratory system include trachea, bronchi, bronchioles, lungs, and diaphragm. Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood.
The bronchial tree is an essential part of the respiratory system. It consists of several interacting structures, such as the bronchi, bronchioles, and alveoli. These structures work together to provide a network system between the lungs and the trachea.Without this system, a person could not breathe properly.he primary bronchi also branch off, forming two smaller bronchial tubes known as the lobar bronchi, or secondary bronchi. There are three lobar bronchi on the right side and two on the left. The bronchiole treeâs parts continue reducing in size as these secondary bronchi become smaller tubes known as the bronchioles.