Air enters through the nose and mouth and passes through the pharynx into the larynx (where the vocal cords are located). Food entering the mouth also passes through the pharynx. It is prevented from entering the lungs by the epiglottis, which folds down over the larynx when swallowing.
From the larynx air enters the trachea which splits into the right and left main bronchi which enter the right and left lungs. The bronchi keep branching into many smaller airways, the smallest of which is the bronchiole (not shown). From the bronchioles branch the alveoli or “air sacs”.
The diaphragm is an important muscle used for breathing.
