Welcome, today I shall write on respiration. Air
enters the body either through the mouth or the
nostrils (external openings leading to the nasal
cavity). The mouth and the naval cavity opens
into the pharynx. Pharynx is a short passageway,
which branches at the end in two directions. One
leads to the digestive tract, and the other to the
larrynx (voice box) and the lower air pathways.
Glottis is the entrance to the larynx. During
swallowing, a flap (epiglottis) covers the glottis to
prevent food and liquid from entering the air
pathways. When the glottis opens, air enters the
larynx. The larynx leads to the trachea (wind
pipe) which branches into two bronchi (singular:
bronchus), the air tubes that enter the lungs.
Each bronchus branches repeatedly within the
lungs to form smaller air tubes. All these air tubes
are kept open by incomplete rings of cartilage to
allow air flow. The smaller air tubes are called
bronchioles. Very fine branches of the
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