transporting air to the exchange surfaces of the lungs including
alveolar ducts
alveolar sacs and finally the
alveoli
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A normal bronchiole usually 1mm or less in diameter. The wall consists of ciliated cuboidal epithelium and a layer of smooth muscle. Bronchioles divide into even smaller bronchioles, called terminal bronchioles, which are 0.5 mm or less in diameter and are primarily lined by club cells, and accompanied by a small number of ciliated cuboidal cells.. Respiratory bronchioles are the final division of the bronchioles within the lung and they are .5mm or less in diameter and contain a simple non ciliated cuboidal epithelium and a thin layer of smooth muscle Ashley Davidoff MD TheCommonVein.net lungs-0721
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Membranous Bronchiole Note folded respiratory folded epithelium resting upon connective tissue. Mucous glands and cartilage are not evident. Courtesy Dr. Armando Fraire TheCommonVein.net 32508
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As the terminal bronchial transitions to the respiratory bronchial the mucosa becomes non ciliated and cuboidal Ashley Davidoff TheCommonVein.net lungs-00676
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The Ductal System of the Acinus The diagram shows the ductal system of the acinus, starting with the tick walled terminal bronchiole (tb) that is the last duct of the conducting system of the airways. The respiratory bronchiole (rb) enters the secondary lobule and is the first duct to have diffusion capability. There can be 3 orders of rb’s, and they branch into alveolar ducts, which branch in turn to alveolar sacs until they reach the alveoli, which is the final destination. Courtesy Ashley DAvidoff MD 2019 lungs-0032-low res
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The Acinus, The Duct, and the Artery The pulmonary arteriole accompanies the airway as it carries oxygen from the trachea to the alveoli. They part ways at the alveoli where the pulmonary venule then takes the oxygenated blood from capillary network around the alveoli back to the left atrium. The intimate relationship of the airways and the pulmonary artery and their close approximation in size, is helpful in radiology, firstly to identify these structures and secondly to define disease such as heart failure and bronchiectasis. The acinus as shown in this image 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-0033-low res
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The 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 lungs-0036-low res
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The Secondary Lobule The arteriole and bronchiole lie in the center of the lobule. Pulmonary venules (red) and lymphatics (yellow). lie in the periphery of the lobule 42440b03 Davidoff Art Courtesy Ashley Davidoff MD
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NORMAL VS CENTRILOBULAR EMPHYSEMA STARTING AT THE RESPIRATORY BRONCHIOLE Ashley Davidoff MD
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Normal Acinus and Emphysema Image on the left shows normal size and appearance of terminal bronchioles and alveoli. On the right the image shows the effects on the respiratory bronchioles and when severe, on the alveoli as well Ashley Davidoff MD TheCommonVein.net
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CT scan of Normal Lungs and Lungs with Centrilobular Emphysema Caused by Cigarette Smoking Ashley Davidoff Art TheCommonVein.net
Magnified view of the upper lobes of a 66year female with centrilobular emphysema shows an expanded lobule with a centrilobular vessel in the middle characteristic of centrilobular emphysema Ashley Davidoff MD TheCommonvein.net
