The Comparative Physiology of Respiratory Mechanisms

Krogh, August

doi:10.2307/j.ctv5rdxfn

Cited by 78 publications

(23 citation statements)

References 37 publications

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“…The ventilatory mechanics of the avian and mammalian respiratory systems are fundamentally similar (Krogh, ; King, ; Comroe, ; Gordon et al, ; McLelland, ; Kardong, ). Described very early by Soum () and Zimmer () and more recently expounded by Brackenbury (,, , ); King & Molony (); Fedde (); King & McLelland (), and Scheid & Piiper (), the air sacs respond to changes in the volume of the coelomic (the thoracoabdominal or the visceral) cavity generated by contractions and relaxations of the intercostal muscles: the air is drawn into the lung and the air sacs when the volume of the coelomic cavity increases, a change that causes the pressure in the body cavity and the air sacs to fall below atmospheric whereas air is expelled from the respiratory system after the respiratory muscles relax, causing the volume of the coelomic cavity to decrease and the pressure in the body cavity to exceed that in the atmosphere (Kadono, Okada & Ono, ; Fedde, Burger & Kitchell, ; James et al, ; King & McLelland, ).…”

Section: Airflow In the Avian Respiratory Systemmentioning

confidence: 99%

Pivotal debates and controversies on the structure and function of the avian respiratory system: setting the record straight

Maina

2016

Biological Reviews

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Among the extant air-breathing vertebrates, the avian respiratory system is structurally the most complex and functionally the most efficient gas exchanger. Having been investigated for over four centuries, some aspects of its biology have been extremely challenging and highly contentious and others still remain unresolved. Here, while assessing the most recent findings, four notable aspects of the structure and function of the avian respiratory system are examined critically to highlight the questions, speculations, controversies and debates that have arisen from past research. The innovative techniques and experiments that were performed to answer particular research questions are emphasised. The features that are outlined here concern the arrangement of the airways, the path followed by the inspired air, structural features of the lung and the air and blood capillaries, and the level of cellular defence in the avian respiratory system. Hitherto, based on association with the proven efficiency of naturally evolved and human-made counter-current exchange systems rather than on definite experimental evidence, a counter-current gas exchange system was suggested to exist in the avian respiratory system and was used to explain its exceptional efficiency. However, by means of an elegant experiment in which the direction of the air-flow in the lung was reversed, a cross-current system was shown to be in operation instead. Studies of the arrangement of the airways and the blood vessels corroborated the existence of a cross-current system in the avian lung. While the avian respiratory system is ventilated tidally, like most other invaginated gas exchangers, the lung, specifically the paleopulmonic parabronchi, is ventilated unidirectionally and continuously in a caudocranial (back-to-front) direction by synchronized actions of the air sacs. The path followed by the inspired air in the lung-air sac system is now known to be controlled by a mechanism of aerodynamic valving and not by anatomical valves or sphincters, as was previously supposed. The structural strength of the air and blood capillaries is derived from: the interdependence between the air and blood capillaries; a tethering effect between the closely entwined respiratory units; the presence of epithelial-epithelial cell connections (retinacula or cross-bridges) that join the blood capillaries while separating the air capillaries; the abundance and intricate arrangement of the connective tissue elements, i.e. collagen, elastin, and smooth muscle fibres; the presence of type-IV collagen, especially in the basement membranes of the blood-gas barrier and the epithelial-epithelial cell connections; and a putative tensegrity state in the lung. Notwithstanding the paucity of free surface pulmonary macrophages, the respiratory surface of the avian lung is well protected from pathogens and particulates by an assortment of highly efficient phagocytic cells. In commercial poultry production, instead of weak pulmonary cellular defence, stressful husbandry practices such a...

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Section: Airflow In the Avian Respiratory Systemmentioning

confidence: 99%

Pivotal debates and controversies on the structure and function of the avian respiratory system: setting the record straight

Maina

2016

Biological Reviews

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“…Oxygen diffuses rapidly from tracheal endings to the mitochondria of end cells because of a high diffusivity of O 2 in air compared to fluids and because most insects actively ventilate their tracheal system. Gas phase diffusion is an important process in insect respiration, first discussed by August Krogh (393-395). Convection further aids gas exchange (370, 393, 395, 626, 680, 723, 778, 804, 818).…”

Section: Section 2 Air Breathing In Invertebrates: Transitions From mentioning

confidence: 99%

“…Gas phase diffusion is an important process in insect respiration, first discussed by August Krogh (393-395). Convection further aids gas exchange (370, 393, 395, 626, 680, 723, 778, 804, 818). In small insects or those with low metabolic rate, diffusion is sufficient to meet metabolic demands whereas in large or in metabolically active insects ventilation is necessary.…”

Section: Section 2 Air Breathing In Invertebrates: Transitions From mentioning

confidence: 99%

Evolution of Air Breathing: Oxygen Homeostasis and the Transitions from Water to Land and Sky

Hsia

Schmitz

Lambertz

et al. 2013

Comprehensive Physiology

282

147

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Life originated in anoxia, but many organisms came to depend upon oxygen for survival, independently evolving diverse respiratory systems for acquiring oxygen from the environment. Ambient oxygen tension (PO2) fluctuated through the ages in correlation with biodiversity and body size, enabling organisms to migrate from water to land and air and sometimes in the opposite direction. Habitat expansion compels the use of different gas exchangers, for example, skin, gills, tracheae, lungs, and their intermediate stages, that may coexist within the same species; coexistence may be temporally disjunct (e.g., larval gills vs. adult lungs) or simultaneous (e.g., skin, gills, and lungs in some salamanders). Disparate systems exhibit similar directions of adaptation: toward larger diffusion interfaces, thinner barriers, finer dynamic regulation, and reduced cost of breathing. Efficient respiratory gas exchange, coupled to downstream convective and diffusive resistances, comprise the “oxygen cascade”—step-down of PO2 that balances supply against toxicity. Here, we review the origin of oxygen homeostasis, a primal selection factor for all respiratory systems, which in turn function as gatekeepers of the cascade. Within an organism's lifespan, the respiratory apparatus adapts in various ways to upregulate oxygen uptake in hypoxia and restrict uptake in hyperoxia. In an evolutionary context, certain species also become adapted to environmental conditions or habitual organismic demands. We, therefore, survey the comparative anatomy and physiology of respiratory systems from invertebrates to vertebrates, water to air breathers, and terrestrial to aerial inhabitants. Through the evolutionary directions and variety of gas exchangers, their shared features and individual compromises may be appreciated.

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“…Although we found a positive correlation between the number of embryos and oxygen consumption rate, it does not necessarily imply that mussels had increased ventilation rates. In filter-feeding bivalves, the ventilatory flow is scaled to feeding requirements and greatly exceeds requirements for gas exchange (Krogh, 1941). Oxygen uptake becomes coupled to ventilation only at low flow rates, where the diffusive resistance is increased by a thickening of the diffusive boundary layer on the gill surface (Barker Jørgensen et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Energetic costs in the relationship between bitterling and mussels in East Asia

Methling

Douda

Liu

et al. 2018

Biological Journal of the Linnean Society

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Bitterling fishes and unionid mussels are involved in a two-sided co-evolutionary association. On the one side, bitterling exploit unionids by ovipositing in their gills. On the other side, unionids develop via a larval stage (glochidium) that attaches to fish gills. Both interactions are parasitic and expected to have negative consequences for the host. Here, we examine the effects of this association on the metabolic rates of mussel and fish hosts by measuring oxygen uptake rates (MO 2). Measurements were performed on two widespread and broadly coexisting species, namely the rose bitterling Rhodeus ocellatus and Chinese pond mussel Sinanodonta woodiana. As predicted, we observed an increase in routine MO 2 in mussels parasitized by bitterling, but only when hosting early stages of bitterling embryos that reside in the interlamellar space of the gills and obstruct water circulation. Hosting later-stage bitterling embryos (that reside in the suprabranchial cavity outside the host gills) was not associated with a higher routine MO 2. We did not observe an acute negative effect of glochidial infestations on maximal oxygen uptake rate (MO 2 max), but glochidia-infested bitterling showed consistently lower oxygen consumption rates during recovery from MO 2 max. Our results suggest that acute costs of this mutually parasitic relationship might be mitigated, at least in part, by adaptations to limit infestation rates.

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The Comparative Physiology of Respiratory Mechanisms

Cited by 78 publications

References 37 publications

Pivotal debates and controversies on the structure and function of the avian respiratory system: setting the record straight

Pivotal debates and controversies on the structure and function of the avian respiratory system: setting the record straight

Evolution of Air Breathing: Oxygen Homeostasis and the Transitions from Water to Land and Sky

Energetic costs in the relationship between bitterling and mussels in East Asia

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