Secondary lobule This picture shows us on the left with a white ring around us (we were the tallest) and the other couples who looked so much like us (also ringed). We called our tribe the “bronchovascular bundle” with the one part of the bundle being the progeny of the bronchus and the other the progeny of the pulmonary artery. In the distance at the periphery we could see the pairs from the other friendly tribe – the red pulmonary vein with its smaller yellow buddy the lymphatic. Behind them we could see the transparent window membrane through which we had peaked earlier. Oh my goodness!!! Look what has happened to my body!!!!!!!…… Ashley Davidoff MD. The Common Vein.net 42447b03b01
At this time we were already up in the air and on our journey. This is a picture of me, the terminal bronchiole in teal blue in the centre and my buddy the pulmonary arteriole in royal blue at the doorway of the polyhedral secondary lobule. We were told by our guide to prepare ourselves for a “centrilobular” entrance since our entry point was to be through the centre of this doorway. 42448b03 code lung pulmonary secondary lobule pulmonary lobule polyhedral septa interstitium normal anatomy histology Ashley Davidoff MD TheCommonVein.netSecondary lobule Here is a picture of the outside of the polyhedral pulmonary lobule from the side. It looked quite futuristic. Through the transparent side window we saw a couple similar to ourselves. From this vantage point the morphing did not look too different from what we had already been through – division after division – leaner and meaner. Ashley Davidoff MD. The Common Vein.net 42449b02
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 resSecondary lobule This picture was taken just before the real drama started. The image gives a sense of what was to come. You can see here in the house of the lobule that we were all dividing into smaller parts and were getting smaller and the picture was quite colorful and rosy. I fully expected to have intimate contact with the arteriole… but it did not happen as I expected…… Ashley Davidoff MD. The Common Vein.net 42447b05b02The Secondary Lobule 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-0036-low resSecondary Lobule – Lymphatics and Venules Travelling Together 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. 42440b03 Ashley Davidoff MD TheCommonVein.netThe Secondary Lobule Between 10 and 30 acini combine to form a secondary lobule which is between .5- 2 cms in diameter. It is subtended by a single lobar bronchiole (lb), and is accompanied by arterioles, venules, lymphatics and connective tissue. 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 disease processes. Courtesy Ashley Davidoff MD lungs-0035-low resThe Acinus The acinus is defined as a unit of lung consisting of a single first order respiratory bronchiole that subtending a cluster of alveoli reminiscent of a bunch of grapes or berries (acinus in Latin means berry) . The lobular bronchiole (lb) branches into the terminal bronchiole (tb), which then branches into the first order respiratory bronchiole (rb). Subsequent branching after the respiratory bronchiole, includes in order, the alveolar duct (ad), alveolar sac (as), and then finally the berry like alveoli. Courtesy Ashley Davidoff 2019 lungs-0030-low resThe Terminal Bronchiole This artistic rendition of the small parts of the lung shows the beginning of the peripheral system just before it enters the acinus. This duct is called the terminal duct and it is the last part of the ductal system that has no ability for gas exchange. After its first division, the bronchioles become the respiratory bronchioles, and they are the first in the system to have an ability to both transport the gases as well as enable gas exchange. Ashley Davidoff TheCommonVein.net 32645b04b05.8sAcinus. The acinus with its arborizations is shaped more like a bunch of grapes. Courtesy of: Ashley Davidoff, M.D 42650 TheCommonVein.netEmphysema A drawing showing the normal acinus in teal and the abnormal emphysematous acinus in green characterised by destruction of the septal walls, enlargement of the alveoli, and loss of elasticity. The absence of involvement of the respiratory bronchiole makes the pathological diagnosis of centrilobular emphysema. Ashley Davidoff MD TheCommonVein.net 32645
The Alveolus
Alveoli of the Lung – Factory Workers This is a drawing of a cluster of alveoli surrounded by the capillary network, fed by an arteriole in blue, and drained by a venule in red. The second image shows the exchange of life giving oxygen for the by product of metabolic activity – carbon dioxide Ashley Davidoff MD TheCommonVein.net 32165cThe alveolus – the center of the pulmonary universe
The five major layers that keep the air moving include the outer bony cage, the muscular layer represented in maroon, the pleural complex (orange yellow orange) the lung (blue) and surfactant within the alveolus. (pink) 42530b05b09b01a08
Ashley Davidoff art
by Ashley Davidoff MDAlveolus Cells and Capillaries of the Lung
“Alveolus Cells and Capillaries of the Lung” shows an alveolus with single cell lining and associated arteriole, capillary and venous circulation. The cool fresh air flows into the alveolus, and oxygen flows into the blue blooded arteriole converting into a red blooded venule. A breeze of carbon dioxide flows through the single celled alveolus and into the airways for expiration
by Ashley Davidoff MDAlveolus Cells and Capillaries of the Lung
“Alveolus Cells and Capillaries of the Lung” shows an alveolus with single cell lining and associated arteriole, capillary and venous circulation. The cool fresh air flows into the alveolus, and oxygen flows into the blue blooded arteriole converting into a red blooded venule. A breeze of carbon dioxide flows through the single celled alveolus and into the airways for expiration
by Ashley Davidoff MDAlveolus Cells and Capillaries of the Lung
“Alveolus Cells and Capillaries of the Lung” shows an alveolus with single cell lining and associated arteriole, capillary and venous circulation. The cool fresh air flows into the alveolus, and oxygen flows into the blue blooded arteriole converting into a red blooded venule. A breeze of carbon dioxide flows through the single celled alveolus and into the airways for expiration
by Ashley Davidoff MD
by Ashley Davidoff MD
Alveolus at a Cytologic Level
The diagram shows an alveolus (a) above, lined by a single layer of squamous cells, surrounded by a capillary with red cells which is also lined by a single layer of squamous endothelial cells . The images below show progressive magnification of the alveolar wall demonstrating the two thin layer of the alveolar membrane .
Courtesy Ashley Davidoff 2019
lungs-0028-low res
Type I Pneumocyte –
Squamous Cell
Ashley Davidoff MDType II Pneumocyte
Ashley Davidoff MDMacrophage
Ashley Davidoff MD