It makes cleaning easier. Secretions build up on the inside which can be removed and easily cleaned and reinserted or replaced.
Infection is the biggest threat.
The air in the lungs may become drier, and more bacteria may enter the trachea.
They terminate at the alveolar sacs which contain the alveoli. Here inhaled O2 is exchanged for exhaled CO2 via the pulmonary veins (which transport de-oxygenated blood with CO2), to the pulmonary...
Tube (튜브 Tubeu), the 2003 South Korean action thriller film directed by Baek Woon-hak