Alveolar duct
1892714
214122271
2008-05-22T05:00:57Z
Nakon
676502
Reverted edits by [[Special:Contributions/Paxillian|Paxillian]] ([[User talk:Paxillian|talk]]) to last version by 139.102.150.90
{{Infobox Anatomy |
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Caption = Detailed drawing of the alveoli from '''[[Gray's Anatomy]]''', 1918 - Schematic longitudinal section of a [[primary lobule]] of the [[lung]] (anatomical unit);<BR>r. b [[respiratory bronchiole]];<BR>al. d alveolar duct; at atria;<BR>a. s [[alveolar sac]];<BR>'a' alveolus or air cell;<BR>p. a.: [[pulmonary artery]];<BR> p. v [[pulmonary vein]];<BR>l [[lymphatic]];<BR>l. n [[lymph node]].] |
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Caption2 = Part of a secondary lobule from the depth of a human [[lung]], showing parts of several [[primary lobules]].<BR>1, [[bronchiole]];<BR>2, respiratory bronchiole;<BR>3, alveolar duct;<BR>4, [[atria]];<BR>5, [[alveolar sac]];<BR>6, [[alveolus]] or air cell:<BR>m, [[smooth muscle]];<BR>a, branch [[pulmonary artery]];<BR>v, branch [[pulmonary vein]];<BR>s, [[septum]] between [[secondary lobules]]. |
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'''Alveolar ducts''' are the tiny end ducts of the branching airways that fill the [[lung]]s. Each lung holds approximately 1.5 to 2 million of them. The tubules divide into two or three [[alveolar sac]]s at the [[distal]] end. They are formed from the confluence openings of several alveoli. Distal terminations of alveolar ducts are atria which then end in alveolar sacs.
In human anatomy, respiratory [[bronchioles]] exists proximal to the alveolar ducts. The epithelial lining consists of smooth muscle knobs covered by nonciliated, simple cuboidal cells. The smooth muscle constricts under parasympathetic innervation and relax under sympathetic innervation.
==Additional images==
[[Image:Alveolar duct2.JPG|thumb|250px|left|human alveolar duct]]
<gallery>
Image:Illu bronchi lungs.jpg|Bronchi, bronchial tree, and lungs
</gallery>
==External links==
* {{eMedicineDictionary|Alveolar+duct}}
* {{AnatomyAtlasesMicroscopic|11|229}} - "Alviolar Duct and Alveolar Sacs"
* {{BUHistology|13607loa}} - "Respiratory System: lung (sheep), alveolar duct "
* {{UCDavisOrganology|respiratory/lung/lung7/lung3}} - "Mammal, lung (EM, Medium)"
* {{USCHistology|lng/c_29}}
{{respiratory-stub}}
{{Lung}}