Tennis Courts in the Human Body: A Review of the Misleading Metaphor in Medical Literature

Rao, Amogh Ananda; Johncy, Smilee

doi:10.7759/cureus.21474

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…For a 45 kg body mass ostrich, with a total volume off the lung of 1.6 l, 250 cm 3 of pulmonary capillary blood volume is exposed to air over a respiratory surface area of 183 m 2 across a tissue barrier 0.560 µm thin (Maina and Nathaniel, 2001): the respiratory surface area is about that of a singles tennis. Particularly in popular literature, the allegoric statement that the respiratory surface area of the human lung is equivalent to that of a tennis court (Koeppen et al, 2010) is greatly over-exaggerated (Rao and Johncy, 2022): the surface area which is ∼135 m 2 (average of the alveolar surface area and that of the pulmonary capillary endothelium) (Gehr et al, 1978) is not even close to that of a singles tennis court! : the definite measurements of a tennis court are 195.71 m 2 for a singles court and 260.86 m 2 for a doubles one (https://olympics.com/en/featured-news/tenniscourt-markings-dimensions-size-types-variety-surfacehard-gra ss-clay-accessed on 23-02-2022).…”

Section: Pulmonary Capillary Blood Volumementioning

confidence: 99%

Perspectives on the Structure and Function of the Avian Respiratory System: Functional Efficiency Built on Structural Complexity

Maina

2022

Front. Anim. Sci.

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Among the air-breathing vertebrates, regarding respiratory efficiency, the avian respiratory system rests at the evolutionary zenith. Structurally, it is separated into a lung that serves as a gas exchanger and air sacs that mechanically ventilate the lung continuously and unidirectionally in a caudocranial direction. Largely avascular, the air sacs are delicate, transparent, compliant and capacious air-filled spaces that are not meaningfully involved in gas exchange. The avian lungs are deeply and firmly attached to the vertebrae and the ribs on the dorsolateral aspects, rendering them practically rigid and inflexible. The attachment of the lung to the body wall allowed extreme subdivision of the exchange tissue into minuscule and stable terminal respiratory units, the air capillaries. The process generated a large respiratory surface area in small lungs with low volume density of gas exchange tissue. For the respiratory structures, invariably, thin blood-gas barrier, large respiratory surface area and large pulmonary capillary blood volume are the foremost adaptive structural features that confer large total pulmonary morphometric diffusing capacities of O2. At parabronchial level, the construction and the arrangement of the airway- and the vascular components of the avian lung determine the delivery, the presentation and the exposure of inspired air to capillary blood across the blood-gas barrier. In the avian lung, crosscurrent-, countercurrent- and multicapillary serial arterialization systems that stem from the organization of the structural parts of the lung promote gas exchange. The exceptional respiratory efficiency of the avian respiratory system stems from synergy of morphological properties and physiological processes, means by which O2 uptake is optimized and high metabolic states and capacities supported. Given that among the extant animal taxa insects, birds and bats (which accomplished volancy chronologically in that order) possess structurally much different respiratory systems, the avian respiratory system was by no means a prerequisite for evolution of powered flight but was but one of the adaptive solutions to realization of an exceptionally efficient mode of locomotion.

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Section: Pulmonary Capillary Blood Volumementioning

confidence: 99%

Perspectives on the Structure and Function of the Avian Respiratory System: Functional Efficiency Built on Structural Complexity

Maina

2022

Front. Anim. Sci.

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“…The mucosal barrier in the lung is barely one cell-layer thick epithelial surface and is one of the largest in the body ( 6 , 7 ). Mucosal defense of the lung includes the physical barrier of the epithelium and its intercellular junctions, mucociliary clearance, epithelial production of antimicrobial peptides (AMP) and oxidative agents as well as transport of IgA antibodies, as well as professional innate and adaptive immune cells, most of which are altered in COPD ( 8 ).…”

Section: Introductionmentioning

confidence: 99%

Mucosal immune alterations at the early onset of tissue destruction in chronic obstructive pulmonary disease

de Fays,

Geudens,

Gyselinck

et al. 2023

Front. Immunol.

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RationaleCOPD is characterized by chronic airway inflammation, small airways changes, with disappearance and obstruction, and also distal/alveolar destruction (emphysema). The chronology by which these three features evolve with altered mucosal immunity remains elusive. This study assessed the mucosal immune defense in human control and end-stage COPD lungs, by detailed microCT and RNA transcriptomic analysis of diversely affected zones.MethodsIn 11 control (non-used donors) and 11 COPD (end-stage) explant frozen lungs, 4 cylinders/cores were processed per lung for microCT and tissue transcriptomics. MicroCT was used to quantify tissue percentage and alveolar surface density to classify the COPD cores in mild, moderate and severe alveolar destruction groups, as well as to quantify terminal bronchioles in each group. Transcriptomics of each core assessed fold changes in innate and adaptive cells and pathway enrichment score between control and COPD cores. Immunostainings of immune cells were performed for validation.ResultsIn mildly affected zones, decreased defensins and increased mucus production were observed, along CD8+ T cell accumulation and activation of the IgA pathway. In more severely affected zones, CD68+ myeloid antigen-presenting cells, CD4+ T cells and B cells, as well as MHCII and IgA pathway genes were upregulated. In contrast, terminal bronchioles were decreased in all COPD cores.ConclusionSpatial investigation of end-stage COPD lungs show that mucosal defense dysregulation with decreased defensins and increased mucus and IgA responses, start concomitantly with CD8+ T-cell accumulation in mild emphysema zones, where terminal bronchioles are already decreased. In contrast, adaptive Th and B cell activation is observed in areas with more advanced tissue destruction. This study suggests that in COPD innate immune alterations occur early in the tissue destruction process, which affects both the alveoli and the terminal bronchioles, before the onset of an adaptive immune response.

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Green CO2 technology for the preparation of aerogel dry powder loaded with beclomethasone dipropionate

Duong,

López-Iglesias,

Bianchera

et al. 2024

Journal of CO2 Utilization

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Tennis Courts in the Human Body: A Review of the Misleading Metaphor in Medical Literature

Cited by 3 publications

References 24 publications

Perspectives on the Structure and Function of the Avian Respiratory System: Functional Efficiency Built on Structural Complexity

Perspectives on the Structure and Function of the Avian Respiratory System: Functional Efficiency Built on Structural Complexity

Mucosal immune alterations at the early onset of tissue destruction in chronic obstructive pulmonary disease

Green CO2 technology for the preparation of aerogel dry powder loaded with beclomethasone dipropionate

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