Diagrams Alveoli | The Common Vein

lungs

The 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) by Ashley Davidoff MD TheCommonVein.net lungs-0014 aka 42530b05b09b01a08

The Squamous Epithelium of the Alveolus
The diagram shows an alveolus, lined by a single layer of squamous cells,
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Exchange of Gases Across the Alveolar Membrane
The diagram shows an alveolus, 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 show exchanges of oxygen and carbon dioxide through the alveolar membrane .
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Alveolus as a Part of the Acinus
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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.
key words
key words RS lung alveolus respiratory bronchiole artery vein pulmonary capillary normal anatomy histology drawing
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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 .
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A Floating Alveolus
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The Alveolus 3D
This drawing demonstrates the open mouth view of the alveolus, which is surrounded by its tree like capillary network. The lining single layer of squamous cells (pneumocytes) can be seen peaking through the vessels.
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The Alveolus 3D
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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
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The Secondary Lobule With Normal Alveoli
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Cellular Makeup of the Normal Alveolus
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The Alveolus
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Alveoli in an Acinus of a Secondary Lobule
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Normal Alveoli in the The Secondary Lobule
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The Acinus, The Duct, and the Artery
The pulmonary arteriole (pa) accompanies the lobular bronchiole (lb). The arteriole transports deoxygenated blood and the bronchiole carries oxygen from the trachea to the alveoli.
They part ways at the alveoli
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Disease

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Inflamed Alveoli
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Hyaline Membrane
A hyaline membrane evolves covering the damaged surface of the alveolus. This impedes gas exchange
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Result of Cellular Response and Associated Tissue Injury
The damage to the endothelium of the capillary results in bleeding into the alveoli. The severe tissue damage and fluid exudation results in protein rich intra-alveolar fluid . The fibroblasts start to lay down collagen as part of the early repair process
Ashley Davidoff
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Result of Cellular Response
The cells of the immune system release cytokines, chemotactic agents and proteases. Immune cells , macrophages and fibroblasts are attracted to the interstitium. Some of proinflammatory agents are toxic to the cell lining causing damage to the surfactant, type 1 pneumocytes and the capillary endothelium. There is progressive edema.
Ashley Davidoff
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Early Events in the Pathophysiology of the ARDS
The initial injury results in an acute severe inflammatory response consisting hyperemia , edema with migration initially of neutrophils in the first 6-24 hours followed by monocytes (24-48hours). The intra -alveolar macrophages are activated.
Ashley Davidoff
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ARDS ? Causes
The lung is injured either by direst causes most commonly pneumonia, aspiration or from inhalation of toxic substances. Severe systemic illnesses, most commonly sepsis with shock, and severe trauma are considered indirect causes.
Ashley Davidoff
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Pathophysiology of Cigarette Smoking on Medium Sized Airways, Small Airways and Alveoli
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NORMAL VS CENTRILOBULAR EMPHYSEMA STARTING AT THE RESPIRATORY BRONCHIOLE
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The Red Snapper – Mycobacterium TB vs the Alveolar Macrophage – Initial Encounter
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Smoking and the Alveolus –
The effect of the proteases and and elastases cause destruction of the alveoli and loss of elasticity, and therefore overall function. The destruction leads to bullous disease
The accumulation of smokers macrophage, and in the case of Langerhans cell histiocytosis leads to space occupation of the alveoli also reducing function
Ashley Davidoff
TheCommonVein.net
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Understanding Radiology and the Alveoli

Filled and Half-Filled Alveoli – Differences in Appearance on CT
When the alveoli are fully filled with fluid, tumor, or pus for example, the overall net density will be white, and when adjacent to air filled airways, air bronchograms are visible (left side of image)
When the alveoli are only partially filled, the density of the fluid added to the density of the air results in an overall gray density, and when positioned next to air filled bronchi, there is insufficient contrast to create an air bronchogram and sufficient to enable visualization of the blood vessels. This is called ground glass opacification
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Ground Glass as a result of Cellular Accumulations in the Alveoli
When there are extensive ceelular accumulations in the alveoli, such as adenocarcinoma with lepidic growth, Langerhans cells or other macrophages, the overall net density of the region of involvement will be gray, and when adjacent to the black air filled airways, a ground glass appearance will be apparent
Ashley Davidoff
TheCommonVein.net
ssb = subsegmental bronchiole
tb = terminal bronchiole
rb = respiratory bronchiole
as = alveolar duct
as = alvelar sac
is = anteralveolar septum
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Ground Glass as a result of Interstitial Disease –
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Radiology of Consolidations
Black White and Gray Densities
The filling of alveoli with fluids or cells results in a density that is ?white? on X-ray and CT scan and is in distinct contrast to the black of the air filled airways. This contrast results in an air bronchogram. The smaller airways in a normal patient are not usually visualized because the ?black? of the of the airways and the black of the air filled alveoli does not create a contrast.
Ashley Davidoff MD TheCommonvein.net
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Radiology of Ground Glass and and Solid Consolidations
Black White and Gray Densities
An air filled alveolus appears as black, a fluid filled alveolus appears as white and a a half filled alveolus appears as gray
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Anatomy of the Distal Airways in Color and in the Black and White of Radiology
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Interstitial changes (red parts of alveoli ) representing either infiltration into the interstitium or inflammatory changes in the interalveolar interstitium
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Alveolitis
Diagram shows inflammation (red ) in the walls of the alveoli with thickening of the interlobular septa (maroon) . The increased density in the interalveolar septa and interlobular septa results in a ground glass opacity with and crazy paving appearance on CT scan
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Alveolitis
Diagram shows inflammation (red ) in the walls of the alveoli. The increased density in the interalveolar septa results in a ground glass opacity on T scan
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Acute Inflammation ? The Basics
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Hypersensitivity Pneumonitis is a disease that most commonly affects the midlung field Next in frequency are the upper lung field and lastly diffuse involvement. Anatomically the small airways and the alveoli are affected with inflammation and granulomas are present
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Types of Fluid Accumulations and Appearance as Ground Glass Infiltrates
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Types of Fluid Accumulation in the Alveoli
The acute inflammatory process results in fluid exudation into the alveoli which can take the form of a serous transudate, and exudate or in the form of mucus, and when severe (eg ARDS) can result in tissue and vessel destruction and could be be blood tinged. Infected fluid could be mucoid or purulent. The extent of filling the alveoli results either in a ground glass appearance when partially filled or a consolidation when filled.
Ashley Davidoff MD TheCommonVein.net
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Consolidation Caused by Fluid Accumulation Consolidation is the replacement of air with solid material resulting in obscuration of blood vessels and airway walls The replacement may be due to fluids including transudate, exudate, mucus, pus, blood, or a combination but may also be replaced by aspirated material or tumor
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Half Filled Cellular Accumulation in the Alveolus
Ground Glass Opacity (GGO) Caused by Cellular Accumulation with Partial Filling of the Alveolus Ground glass opacification may be caused by partial filling of the alveolus with cellular material with partial replacement of air with solid material with the net density being gray rather than white if the alveolus were fully filled. The black of the airway nor the white of the vessels may blend with the gray density and hence they are not visualized in ground glass opacities.
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Pneumonia
The collage provides a perspective of purulent accumulation in the small airways and the alveoli that results in consolidation. A process that increases the density of the lungs to a net “white” regional density will result in a consolidation and in this case when the fluid is infected it is labelled “pneumonia” The net result on CT is air bronchograms within the non aerated dense lung tissue.
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Alveolar Proteinosis

Accumulation of proteinaceous material in the alveoli, impairing gas exchange and leading to respiratory failure. Extensive thickening of interlobular septa leading to crazy paving appearance. Half filled alveoli lead to ground glass appearance
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The collage provides a perspective of disease of the small airways and the alveoli that results in ground glass appearance on Xray. A process that increases the density of the lungs to a net “gray” regional density will result in a ground glass opacity whether it is inflammation of the walls ((second column) fluid within the lumen of the small air ways and alveoli (3rd column) or whether it is fibrosis in the walls of the small airways or alveolar septa (last column alveoli. The net result on CT is a ground glass opacity (bottom row). In fibrosis there are secondary changes which include bronchiolectasis in this case, but other associated changes may include reticulations or centrilobular nodules
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Fibrotic Diseases

Intralobular, interstial – interalveolar fibrosis (white) between the alveoli
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Progressive, Diffuse Intralobular, interstitial – interalveolar fibrosis (white) between the alveoli
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Honeycomb Lung
In patients with interstitial lung disease, the inflammatory process and interstitial fibrotic disease progresses and the walls between the alveoli are destroyed causing large subpleural, variably sized, subpleural, thick walled, stacked, cystic spaces . The appearance is reminiscent of a honeycomb and indicates end stage fibrosis
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NSIP

Ground Glass as a result of Interstitial Disease –
When there are extensive interstitial fibrotic changes in the interstitial compartments of the lung which include the and the interalveolar septa, and the supporting interstitium of the lung between the acini and small airways, the overall net density of the region of involvement will be gray, and when adjacent to the black air filled airways, a ground glass appearance will be apparent
Ashley Davidoff
TheCommonVein.net
ssb = subsegmental bronchiole
tb = terminal bronchiole
rb = respiratory bronchiole
as = alveolar duct
as = alvelar sac
is = anteralveolar septum
Ashley Davidoff
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COVID 19

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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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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The Devil is in the Chest and Lungs and has One Mission
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Eosinophilic Pneumonia

TCV