In this section, air is purified and humidified.
In the first section, the internal wall has several capillaries, which warm up the air because they carry blood.
Each tube enters a different lung.
Trachea
The walls of this tube are formed of cartilage that continually keeps it open.
The presence of nooks and crannies in this section of the respiratory tract increases the lenght of the journey air goes within the body, making it warmer.
They branch into progressively smaller ducts.
They are two airways.
Bronchi
Where air enters the body.
This area is common to the respiratory and digestive tracts. Foods continue their journey into the esophagus, while air passes into the larynx.
It has open cartilage rings at its back.
Larynx
It's about 12 cm long.
There's mucous present in the interior of this section that traps foreign particles in the air.
They don't have cartilage rings.
They end in tiny sacts, called pulmonary alveoli.
Nasal cavity
Bronchioles
On the sides of this airway there are tonsils, which produce white blood cells.
Entry to this area is regulated by a fibrous structure known as the epiglottis, which closes when food is being ingested to prevent the organism from choking or suffocating.
In this part of the respiratory tract there are certain cells with vibrating filaments know as cilia.
Pharynx