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.
Digestive system: The alimentary canal and accessory digestive organs. Organs of the digestive system are divided into two main groups: organs within the alimentary canal and accessory digestive organs. The alimentary canal, which is also called the gastrointestinal (GI) tract or gut, is the entire length of tube that winds through the body from the mouth to the anus.