Bronchus - Definition and Function

What is Bronchus, Definition and Function

Bronchus is a secondary branch of the airways that connect the LUNGS and the primary airway, the TRACHEA. The main bronchi branch directly from the trachea at about mid-lung, with the right main bronchus channeling air to the right lung and the left main bronchus directing air to the left lung. Each main bronchus nearly immediately branches into lobular bronchi, three in the right lobe and two in the left lobe. Bronchi become diminishingly smaller as they branch deeper into the lungs. Rings of CARTILAGE give larger bronchi rigidity and support. Smaller bronchi have fewer and thinner cartilage rings, and bronchioles, the tiniest of the bronchi, have thin walls of only smooth MUSCLE tissue with no cartilage. The bronchi are susceptible to irritation, INFLAMMATION, and INFECTION. When inflamed or irritated the bronchi can cause difficulty breathing (DYSPNEA).

For further discussion of the bronchi within the context of pulmonary structure and function please see the overview section “The Pulmonary System.”

See also ALVEOLUS; ASTHMA; BRONCHIECTASIS; BRONCHITIS.

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