lungs
The Secondary Lobule
Ashley Davidoff MD TheCommonVein.net lungs-0751
Artistic 3D Rendering Anatomy of the Distal Airways.
The lobular (most distal of the subsegmental airways give rise to the terminal bronchiole which give rise to the membranous airways. These include in order, the respiratory bronchiole, alveolar ducts and alveolar sacs
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The Structure of the Acinus is reminiscent of the morphology of a bunch of grapes.
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The Structure of the Acinus is reminiscent of the morphology of multiple berries and fruits including the strawberry , grapes and mulberry or blackberry.
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The Acinus, The Duct, and the Artery
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The Acinus
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Anatomy of the Distal Airways in Color and in the Black and White of Radiology
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Small Airways
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 2mm or less .  It divides into the respiratory bronchiole (rb) a transitional airway which then advances into the alveolar ducts(ad) and alveolar sacs (as)   Diseases isolated to the small airways do not affect the alveoli and hence there is peripheral sparing Ashley Davidoff MD TheCommonVein.net lungs-0749
The Acinus, The Duct, and the Artery
Ashley Davidoff TheCommonvein.net  lungs-0033
The diagram shows the structure of the airways and alveoli at the level of the secondary lobule. The terminal bronchiole (tb- pink) enters the secondary lobule and terminates in the respiratory bronchiole (rb purple) which lies in the center of the the secondary lobule (centrilobular). It gives rise to alveolar duct (ad yellow)which gives rise to the alveolar sac (as, teal blue. Finally the as terminates in the alveoli (a white)
Courtesy Ashley Davidoff MD
lungs-0028-low res
Artistic 3D Rendering Anatomy of the Distal Airways.
The lobular (most distal of the subsegmental airways give rise to the terminal bronchiole which give rise to the membranous airways. These include in order, the respiratory bronchiole, alveolar ducts and alveolar sacs
Ashley Davidoff TheCommonvein.net lungs-0004
The Acinus with a lobular bronchiole, terminal bronchioles, respiratory bronchioles and alveoli. (alveolar duct and alveolar sacs are not shown)
Ashley Davidoff The CommonVein.net lungs-0002

Diseases

COVID

INHALATION
The virus enters the lungs and travels to the smallest parts of the lungs, tiny lung sacs called the alveoli where oxygen exchange takes place
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CELLULAR INVASION
Corona virus invades the cells of the alveoli by using its spike glycoproteins. These spike proteins attach to the cell membrane and the virus can then enter the cell.
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INFLAMMATION
The virus replicates and invades more cells of the alveoli
As COVID-19 causes inflammation of the the lungs, infected fluid fills the lungs thus disrupting gas exchange.
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PROGRESSION
and progresses to involve more and more lung
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NORMAL VS CENTRILOBULAR EMPHYSEMA STARTING AT THE RESPIRATORY BRONCHIOLE
Ashley Davidoff MD
TheCommonVein.net lungs-0038