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.
Respiratory System. The upper respiratory tract (upper airway) consists of the nose, mouth, sinuses, and throat. The lower respiratory tract consists of the trachea, bronchial tubes, and the structures inside the lungs. Credits. Primary Medical ReviewerE.