Bronchus
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Keilana
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Reverted edits by [[Special:Contributions/122.53.112.22|122.53.112.22]] to last version by Thijs!bot (using [[WP:HG|Huggle]])
{{Infobox Anatomy |
Name = {{PAGENAME}} |
Latin = |
GraySubject = 237 |
GrayPage = 1084 |
Image = Respiratory system complete numbered.svg|
Caption = Conducting passages. |
Image2 = Gray961.png |
Caption2 = Front view of cartilages of larynx, trachea, and bronchi. |
Precursor = |
System = respiratory |
Artery = [[bronchial artery]] |
Vein = [[bronchial vein]] |
Nerve = [[pulmonary branches of vagus nerve]] |
Lymph = |
MeshName = Bronchi |
MeshNumber = A04.411.125 |
DorlandsPre = b_23 |
DorlandsSuf = 12198294 |
}}
A '''bronchus''' (plural '''bronchi''', adjective '''bronchial''') is a caliber of airway in the [[respiratory tract]] that conducts air into the [[lung]]s.<ref>{{cite book
| last = Maton
| first = Anthea
| authorlink =
| coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright
| title = Human Biology and Health
| publisher = Prentice Hall
| date = 1993
| location = Englewood Cliffs, New Jersey, USA
| pages =
| url =
| doi =
| id =
| isbn = 0-13-981176-1}}</ref>
No [[gas exchange]] takes place in this part of the lungs.
==Anatomy==
The [[Vertebrate trachea|trachea]] (windpipe) divides into two main '''bronchi''' (also '''mainstem bronchi'''), the left and the right, at the level of the [[sternal angle]]. The [[right main bronchus]] is wider, shorter, and more vertical than the [[left main bronchus]]. The right main bronchus subdivides into three segmental bronchi while the left main bronchus divides into two. The lobar bronchi divide into [[tertiary bronchus|tertiary bronchi]]. Each of the segmental bronchi supplies a [[bronchopulmonary segment]]. A bronchopulmonary segment is a division of a lung that is separated from the rest of the lung by a [[connective tissue]] [[septum]]. This property allows a bronchopulmonary segment to be surgically removed without affecting other segments. There are ten segments per lung, but due to anatomic development, several segmental bronchi in the left lung fuse, giving rise to eight. The segmental bronchi divide into many [[primary bronchiole]]s which divide into [[terminal bronchiole]]s, each of which then gives rise to several [[respiratory bronchiole]]s, which go on to divide into 2 to 11 [[alveolar duct]]s. There are 5 or 6 [[alveolar sac]]s associated with each alveolar duct. The [[pulmonary alveolus|alveolus]] is the basic anatomical unit of gas exchange in the lung.
There is [[hyaline 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.
In the [[mediastinum]], at the level of the fifth [[thoracic vertebra]], the trachea divides into the right and left primary bronchi. The bronchi branch into smaller and smaller passageways until they terminate in tiny air sacs called alveoli.
The [[cartilage]] and [[mucous membrane]] of the primary bronchi are similar to that in the trachea. As the branching continues through the bronchial tree, the amount of [[hyaline cartilage]] in the walls decreases until it is absent in the smallest bronchioles. As the cartilage decreases, the amount of smooth muscle increases. The mucous membrane also undergoes a transition from ciliated pseudostratified columnar epithelium to simple [[cuboidal epithelium]] to simple [[squamous epithelium]].
The [[alveolar ducts]] and [[alveoli]] consist primarily of simple [[squamous epithelium]], which permits rapid diffusion of [[oxygen]] and [[carbon dioxide]]. Exchange of gases between the air in the lungs and the blood in the [[capillaries]] occurs across the walls of the alveolar ducts and alveoli.
==Role in disease==
[[Bronchitis]] is defined as inflammation of the bronchi. There are two main types: acute and chronic. Acute bronchitis is usually caused by viral or bacterial infections. [[Chronic bronchitis]] is a form of [[COPD]], usually associated with smoking or long-term exposure to irritants.
[[Asthma]] is hyperreactivity of the bronchi with an inflammatory component, often in response to [[allergen]]s.
While the left mainstem bronchus departs from the trachea at an angle, the right mainstem bronchus is almost a vertical continuation of the trachea. This anatomy predisposes the right lung to several problems:
*If food, liquids, or foreign bodies are aspirated, they often will lodge in the right mainstem bronchus. [[Aspiration pneumonia]] may result.
*If the [[endotracheal tube]] used for [[intubation]] is inserted too far, it usually lodges in the right mainstem bronchus. This allows ventilation of the right lung, but leaves the left lung useless.
*Patients with inadequate [[cough]] reflexes may develop chronic right middle lobe lung infections such as the [[Lady Windermere Syndrome]].
==Additional images==
[[Image:Bronchi.JPG|thumb|250px|cross sectional cut of a human secondary bronchus]]
<gallery>
Image:Gray503.png|Transverse section of thorax, showing relations of pulmonary artery.
</gallery>
==References==
* Moore, Keith L. and Arthur F. Dalley. ''Clinically Oriented Anatomy, 4th ed.'' (1999). ISBN 0-7817-5936-6
[[Category:Respiratory system]] [[Category:Thorax]]
{{Respiratory system}}
{{Lung}}
[[bg:Бронхи]]
[[ca:Bronqui]]
[[cs:Průduška]]
[[da:Bronkie]]
[[de:Bronchialsystem]]
[[dv:ވައި ނޮޅީގެ ކަފި]]
[[es:Bronquio]]
[[eo:Bronko]]
[[fr:Bronche]]
[[id:Bronkus]]
[[it:Bronco]]
[[he:סמפון]]
[[la:Bronchus]]
[[lt:Bronchas]]
[[mk:Бронхии]]
[[nl:Luchtpijpvertakking]]
[[no:Bronkietreet]]
[[pl:Oskrzela]]
[[pt:Brônquios]]
[[ru:Бронхи]]
[[fi:Keuhkoputki]]
[[sv:Bronk]]
[[uk:Бронхи]]