The normal human lung: ultrastructure and morphometric estimation of diffusion capacity

Gehr, Peter; Bachofen, M; Weibel, Ewald R.

doi:10.1016/0034-5687(78)90104-4

Cited by 556 publications

(339 citation statements)

References 22 publications

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“…Kumar et al [19] considered honeycomb shapes for acinar geometries to investigate particle transport in these regions. Other studies also considered a polyhedral shape for alveoli models [20] [21]. Several 3D geometrical models of the alveolus airways have been previously completed.…”

Section: Geometrymentioning

confidence: 99%

Investigation of the Effects of Emphysema and Influenza on Alveolar Sacs Closure through CFD Simulation

Aghasafari¹,

Ibrahim²,

Pidaparti³

2016

JBiSE

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Emphysema and influenza directly affect alveolar sacs and cause problems in lung performance during the breathing cycle. In this study, the effects of Emphysema and Influenza on alveolar sac's air flow characteristics are investigated through Computational Fluid Dynamics (CFD) simulation. Both normal and Emphysemic alveolar sac models with varying collapsed volumes resulting from influenza virus replication were developed. Maximum, area average pressure, and wall shear stress (WSS) in collapsed and open alveolar sacs models were compared. It was found that a collapse at half of the volume at the bottom of the alveolar sacs' models would cause a decrease in average and maximum pressure values and yield higher WSS values for fluid flow during the breathing cycle. On the other hand, a quarter volume collapse at the bottom and side of the model resulted in higher values for average and maximum pressure and WSS. Additionally, results also showed that a combination of alveolar sacs closure and Emphysema would generally lead to an increase in fluid pressure and average WSS during breathing. Maximum WSS was observed during exhalation and maximum WSS decrease occurred during inhalation. Findings are in good agreement with previous studies and suggest that emphysema and influenza virus affect fluid flow and may contribute to alveolar sac closure. However, more realistic simulations should include the fluid-solid interaction studies.

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Section: Geometrymentioning

confidence: 99%

Investigation of the Effects of Emphysema and Influenza on Alveolar Sacs Closure through CFD Simulation

Aghasafari¹,

Ibrahim²,

Pidaparti³

2016

JBiSE

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“…Burri, 1985; Brain, 1996), it has a respiratory surface area (RSA) of ~140 m 2 (about the size of a tennis court) which is located in the acini that lie no more than 40 to 50 cm from the external environment (air) (e.g. Weibel, 1984), and the thickness of the blood-gas (tissue) barrier (BGB) (harmonic mean thickness, ht) is 0.62 μm, a value about one-fiftieth of the thickness of a foolscap paper or that of a human head hair (Gehr et al, 1978(Gehr et al, , 1990a. By weight, each day, more than 20 kg of air enters and leaves the human body, a load that far exceeds that of food and water ingested during the same time period (Brain, 1996).…”

Section: General Considerationsmentioning

confidence: 99%

Cellular Defences of the Lung: Comparative Perspectives

Maina¹

2012

Respiratory Diseases

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'Our lungs are highly complex organs that are exquisitely specialized for gas exchange and host defense.' Rawlins (2010) 1. Introduction General considerationsThe most important function of the lung is to acquire molecular oxygen and eliminate carbon dioxide. Except probably for the gastrointestinal system, no other organ in the body interacts with the external environment as constantly and as intimately as the respiratory system. For example, during a 24 hour period, at rest, the human lung is ventilated ~25,000 times with ~20,000 L of air (e.g. Burri, 1985; Brain, 1996), it has a respiratory surface area (RSA) of ~140 m 2 (about the size of a tennis court) which is located in the acini that lie no more than 40 to 50 cm from the external environment (air) (e.g. Weibel, 1984), and the thickness of the blood-gas (tissue) barrier (BGB) (harmonic mean thickness, ht) is 0.62 μm, a value about one-fiftieth of the thickness of a foolscap paper or that of a human head hair (Gehr et al., 1978(Gehr et al., , 1990a. By weight, each day, more than 20 kg of air enters and leaves the human body, a load that far exceeds that of food and water ingested during the same time period (Brain, 1996). Depending on the level of air pollution, different types and quantities of foreign particulates and microbial pathogens are inhaled. While large RSA and thin BGB increase gas exchange, the concomitant downside to these structural properties is that they make the lung a leading portal of entry and therefore attack by pathogenic micro-organisms, damage by allergens and particulates, and injury by noxious gases (e.g. Brain, , 1992Lambrecht et al. 2001;Garn et al., 2006). The inhaled particulates are deposited on the epithelial lining of the conducting airways and that of the peripheral air spaces where they are retained for various durations before they are removed or destroyed (e.g. Geiser et al., 1988; Gehr et al., 1990 a, b). Brain (1996) observed that 'the lung is unique in that the marriage between environment and lung disease is profound. The respiratory system threfore forms a huge challenge to the body's immune integrity (e.g. von Garnier and Nicod, 2009 , 1993;Schwartz, 1994;Brunekreef et al., 1995;Ware, 2000;Pope, 2000;Nemmar et al., 2002;Pope et al., 2002;Suwa et al., 2002;Schulz et al., 2005;Kaufman, 2010;Brook et al., 2010; van den Hooven et al., 2011;Kampfrath et al., 2011 gc.ca/ccdpc-cpcmc/crdmrc/facts_gen_e.html). According to the Canadian Lung Association (CLA), the economic burden of respiratory disease in the Country is ~3 billion ($US) dollars (http://www.bukisa.com/articles/455926_lung-health-occupational-healthincidence#ixzz1I4jwMvBX). Based on net changes in gross domestic product (GDP) growth forecasts, the estimated annual cost of SARS (Sudden Avian Respiratory Syndrome) in Asia exceeds 10 billion dollars ($US) (Lee and McKibbin, 2003;Fan, 2003;McKibbin and Sidorenko, 2006) and according to the World Bank's estimates, an influenza pandemic may result in a loss (expenditure) of 800 billion dollars ($US) (Brahm...

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“…The right lung was inflation fixed at 20 cmH 2 O (Gehr et al 1978) via the trachea with 4% paraformaldehyde/2% glutaraldehyde in phosphate buffered saline (PBS, pH 7.3). When the fixation pressure reached a plateau, usually with 25 min, the trachea was occluded and the right lung was submerged in buffered fixative and stored at 4 o C overnight.…”

Section: Harvesting Of Lung Tissuesmentioning

confidence: 99%

Computer‐assisted stereology: Point fraction of lung parenchyma and alveolar surface density in fetal and newborn sheep

et al. 2003

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Summary:The aim of this study was to determine the accuracy of a new computer-assisted stereological technique in obtaining structural information of the lung. We compared the point fraction of lung parenchyma (P p ) and alveolar surface density (S v ) obtained by established manual point/intercept counting methods and compared them with those obtained using a computer-assisted method. Lung tissues obtained from normally grown fetal sheep (n=6) and from newborn lambs with severe lung hypoplasia (n=5) were inflation fixed via the trachea and processed for light microscopy. In verification-of-technique experiments, P p and S v correlated well with known values. There was a significant linear correlation between manual and computerassisted stereological measurements for values of P p (r 2 = 0.92) and S v (r 2 = 0.98). Our data lead us to believe that the computer-assisted stereological technique described in this study provides accurate estimates of P p and S v and hence may be a valuable tool for evaluating the effects of factors upon structural development of the lung.

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The normal human lung: ultrastructure and morphometric estimation of diffusion capacity

Cited by 556 publications

References 22 publications

Investigation of the Effects of Emphysema and Influenza on Alveolar Sacs Closure through CFD Simulation

Investigation of the Effects of Emphysema and Influenza on Alveolar Sacs Closure through CFD Simulation

Cellular Defences of the Lung: Comparative Perspectives

Computer‐assisted stereology: Point fraction of lung parenchyma and alveolar surface density in fetal and newborn sheep

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