A bronchus (plural bronchi, adjective bronchial) is a caliber of airways in the the respiratory tract that conducts air into the lungs. No gas exchange takes place in this part of the lungs.
The trachea (windpipe) divides into two main bronchi, the left and the right. These subdivide in two (left lung) or three (right lung) bronchi that each serve one lobe. The bronchi divide several more generations until they become bronchioles. There is a bronchus going to each segment of each lobe of the lung. Bronchi are generally greater than one millimetre in diameter.
There is still cartilage present in the bronchi, present as irregular rings in the larger bronchi (and not as regular as in the trachea), and as small plates and islands in the smaller bronchi. Smooth muscle is present continuously around the bronchi.
Role in disease
Bronchitis is viral or bacterial infection of the bronchi. Asthma is hyperreactivity of the bronchi with an inflammatory component, often in response to allergens. Chronic bronchitis (COPD) is smoking- or coal dust-induced chronic inflammation of the bronchi that leads to obstruction of the airways.
The bronchial arteries supply blood for the nutrition of the lung; they are derived from the thoracic aorta or from the upper aortic intercostal arteries, and, accompanying the bronchialtubes, are distributed to the bronchial glands and upon the walls of the larger bronchialtubes and pulmonary vessels.
Those supplying the bronchialtubes form a capillary plexus in the muscular coat, from which branches are given off to form a second plexus in the mucous coat; this plexus communicates with small venous trunks that empty into the pulmonary veins.
The bronchial vein is formed at the root of the lung, receiving superficial and deep veins corresponding to branches of the bronchial artery.
Share your thoughts, questions and commentary here
Want to know more? Search encyclopedia, statistics and forums:
Press Releases |
The Wikipedia article included on this page is licensed under the
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m