Airways
Follow air from the nose and mouth through the passages that lead it into the lungs.
Upper and lower airways
The airways are divided into the upper airway, which includes the nose, mouth, and pharynx, and the lower airway, which includes the larynx, trachea, and bronchi.
The airway as a branching structure
Air passes through progressively narrower tubes on its way to the lungs.
Entry points
Air enters through the nasal cavity or oral cavity, where it is warmed, moistened, and partially filtered.
Shared passage
The pharynx is shared with the digestive system, while the larynx contains the vocal cords and marks the entrance to the lower airway.
The windpipe
The trachea is a rigid tube reinforced by cartilage rings that keeps the airway open.
Branching tubes
The trachea divides into bronchi, which branch repeatedly into smaller bronchioles that lead toward the alveoli.
The airways form a branching tree.
Air travels through progressively smaller tubes, similar to branches of a tree, until it reaches the alveoli.
Keeping the airway open and clean
Cartilage rings keep the trachea and large bronchi from collapsing, while mucus and tiny hair-like cilia trap and move particles out of the airway.
Why the airway path matters
Because the pharynx is shared between breathing and swallowing, and the larynx protects the lower airway, this pathway plays a role in both breathing and protecting the lungs from food and liquids.
Airways are the body's air-delivery system.
Every breath must pass through this branching pathway before it can reach the alveoli for gas exchange.