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Normal lung histology
This image is a panoramic view of the lung showing secondary lobules and interlobular septa. Within the interalveolar septae, one sees small venules and lymphatics.Courtesy Armando Fraire MD. 32649b
code lung pulmonary alveoli alveolus secondary lobule interlobular septa vein lymphatic histology
interstitium interstitial
Courtesy of: Armando Fraire, M.D. Ashley Davidoff TheCommonVein.net
32649b
Keywords:
lung pulmonary alveoli alveolus secondary lobule interlobular septa vein lymphatic histology interstitium interstitial normal copyright 2009 all rights reserved
The segments form the secondary lobules.
Normal lung histology. This image of the lung periphery shows secondary lobules and interlobular septa. Within the interlobular septae, one sees small venules and lymphatics. The matrix of the lobule contains alveoli.
Courtesy of: Armando Fraire, M.D. Ashley Davidoff TheCommonVein.net
The arteries and airways pair up and travel together from the interlobular septa to the hilum. The pulmonary lobule, also called the secondary lobule is a structural unit surrounded by a membrane of connective tissue, and it is smaller than a subsegment of lung but larger than an acinus. This diagram shows two secondary lobules lying side by side. The pulmonary arteriole (royal blue) and bronchiole (pink) are shown together in the centre of the lobule (“centrilobular”), while the oxygenated pulmonary venules (red) and lymphatics (yellow) are peripheral and also form a formidable and almost inseparable pair.
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Ashley Davidoff MD
TheCommonVein.net
3D image of the polyhedral shapes secondary lobule with a centrilobular bronchovesicular bundle Ashley Davidoff MD. The Common Vein.net lungs-0003
Ashley Davidoff MD TheCommonVein.net
The top image (a) shows an anatomic drawing of a secondary lobule of the lung subtended by a lobular bronchiole (lb) and arteriole (pa). The interlobular septum contains the venule (red) lymphatic (yellow) and septum (maroon)
The anatomical specimen of the lung (b) shows normal intralobular parenchyma while image c shows the centrilobular arteriole (navy blue) and centrilobular bronchiole (teal) and interlobular venule (red) and lymphatics (yellow) The interlobular septum is slightly thickened
Ashley Davidoff TheCommonVein.net
The secondary lobule is housed in a connective tissue framework in which run the lymphatic and venular tributaries . Together these 3 structures form the interlobular septum.
The lobar arteriole enters the framework, accompanied by the lobar bronchiole, and they all run together and form the interlobular septa. This structure measures between .5cms and 2cms and is visible on CT scan.
It is important in clinical radiology since many of the structures can be identified in health, and more particularly in disease, enabling the identification and characterization of many pathological processes.
Courtesy Ashley Davidoff MD The CommonVein.net lungs-0735
The secondary lobule is subtended by the lobular arteriole (a) and the lobular bronchiole (b) which which in turn branches into the respiratory bronchioles, alveolar ducts, and nd alveolar sacs (c) The acinus (d) consists of a respiratory bronchiole and its associated alveolar ducts, sacs, and alveoli and represents the functional unit of the lung.
The secondary lobule is drained by the pulmonary venule (e) which runs in the interlobular septum also containing the lymphatics (f). The whole unit is housed and surrounded by a connective tissue framework (g) . The latter 3 structures form the interlobular septum.
Ashley Davidoff MD TheCommonVein.net lungs-0751
The diagram allows us to understand the the components and the position of the small airways starting in (a) which is a secondary lobule that is fed by a lobular bronchiole(lb) which enters into the secondary lobule and divides into terminal bronchioles (tb) which is the distal part of the conducting airways, and at a diameter of Ashley Davidoff MD TheCommonVein.net lungs-0744
Image a shows the airways starting in the trachea and continuing to the mainstem bronchi, lobar bronchi, segmental bronchi, and subsegmental bronchi,. The subsegmental bronchi have 3 subsequent generations until the bronchiole is reached. The terminal bronchiole is the last of the transporting airways and is considered the most proximal small airway with a diameter of 2mm or less, and it gives rise to the respiratory bronchiole which is the feeding airway for the acinus . The acinus is the functional unit of the lung.
Image b is a 3D reconstruction of a CT scan showing the proximal airways from the trachea to the segmental airways.
Image c shows the structures that make up the acinus and the other parts of the small airways, starting with the respiratory bronchiole (rb) . The diagram in d, shows the detail of the small airways that participate in gas exchange, including the respiratory bronchiole, (rb) alveolar duct, (ad) and alveolar sac (as)
Image e shows the secondary lobule made from about 20-30 acini, arising from a single lobular bronchiole accompanied by a single pulmonary arteriole (pa).. Structure that surround and enclose the secondary lobule include the pulmonary venule, (red) lymphatics,(yellow) and a fibrous septum (pink).
Ashley Davidoff MD TheCommonVein.net
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