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 trachea, bronchi and bronchioles form the tracheobronchial tree â a system of airways that allow passage of air into the lungs, where gas exchange occurs.ey: Green â upper lobe, yellow â middle lobe, blue â lower lobe. It travels inferiorly into the superior mediastinum, bifurcating at the level of the sternal angle (forming the right and left main bronchi). As it descends, the trachea is located anteriorly to the oesophagus, and inclines slightly to the right.