A morphometric analysis of the lung of a species of bat

Maina, John N.; King, A. S.; King, D.Z.

doi:10.1016/0034-5687(82)90002-0

Cited by 45 publications

(22 citation statements)

References 26 publications

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“…The sources of data for birds are given in Table 1. Those of the non-flying mammals are mainly from Gehr et al (1981) and those of bats come from Maina et al (1982b), Maina and King (1984), and Maina et al (1991) flying mammals and bats, birds have much thinner bloodgas barriers (Fig. 54).…”

Section: Morphometrymentioning

confidence: 96%

The design of the avian respiratory system: development, morphology and function

Maina

2015

J Ornithol

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The avian respiratory apparatus is separated into a gas exchanger (the lung) and ventilators (the air sacs). Synchronized bellows-like movements of the cranial and caudal air sacs ventilate the lung continuously and unidirectionally in a caudocranial direction. With the lungs practically rigid, after their insertion into the ribs and the vertebrae and on attaching to the membranous horizontal septum, surface tension is not a constraining factor to the intensity that the gas exchange tissue can subdivide. Delicate, transparent, capacious and avascular, the air sacs are not directly involved in gas exchange. The airway system comprises of a three-tiered system of passageways, namely a primary bronchus, the secondary bronchi and the tertiary bronchi (parabronchi). The crosscurrent system is formed by the perpendicular arrangement between the mass (convective) air flow in the parabronchial lumen and the centripetal (inward) flow of the venous blood in the exchange tissue; the countercurrent system consists of the centrifugal (outward) flow of air from the parabronchial lumen into the air capillaries and the centripetal (inward) flow of blood in the blood capillaries, and; the multicapillary serial arterialization system is formed by the blood capillaries and the air capillaries where venous blood is oxygenated in succession at the infinite number of points where the respiratory units contact exchange tissue. Together with the aforementioned systems, features like large capillary blood volume, extensive respiratory surface area and thin bloodgas barrier accord high pulmonary diffusing capacity of O 2 that supports the high metabolic capacities and energetic lifestyles of birds.

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Section: Morphometrymentioning

confidence: 96%

The design of the avian respiratory system: development, morphology and function

Maina

2015

J Ornithol

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“…a, Alveoli. Scale bar is 10 m. [From Maina et al (152).] B: lung of a bushbaby, Galago senegalensis, showing type 2 (granular) pneumocytes (g) located at intercapillary junctions away from the blood-gas barrier.…”

Section: Sporadic Attenuation In the Design Of The Blood-gas Barriermentioning

confidence: 99%

“…i, Interstitial cell; e, epithelial cell. Scale bar is 15 m. [From Maina et al (152).] E: blood capillaries (v) in the lung of a bat, Cynopterus brachyotis.…”

Section: Sporadic Attenuation In the Design Of The Blood-gas Barriermentioning

confidence: 99%

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Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier

Maina¹,

West²

2005

Physiological Reviews

177

159

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In gas exchangers, the tissue barrier, the partition that separates the respiratory media (water/air and hemolymph/blood), is exceptional for its remarkable thinness, striking strength, and vast surface area. These properties formed to meet conflicting roles: thinness was essential for efficient flux of oxygen by passive diffusion, and strength was crucial for maintaining structural integrity. What we have designated as "three-ply" or "laminated tripartite" architecture of the barrier appeared very early in the evolution of the vertebrate gas exchanger. The design is conspicuous in the water-blood barrier of the fish gills through the lungs of air-breathing vertebrates, where the plan first appeared in lungfishes (Dipnoi) some 400 million years ago. The similarity of the structural design of the barrier in respiratory organs of animals that remarkably differ phylogenetically, behaviorally, and ecologically shows that the construction has been highly conserved both vertically and horizontally, i.e., along and across the evolutionary continuum. It is conceivable that the blueprint may have been the only practical construction that could simultaneously grant satisfactory strength and promote gas exchange. In view of the very narrow allometric range of the thickness of the blood-gas barrier in the lungs of different-sized vertebrate groups, the measurement has seemingly been optimized. There is convincing, though indirect, evidence that the extracellular matrix and particularly the type IV collagen in the lamina densa of the basement membrane is the main stress-bearing component of the blood-gas barrier. Under extreme conditions of operation and in some disease states, the barrier fails with serious consequences. The lamina densa which in many parts of the blood-gas barrier is <50 nm thin is a lifeline in the true sense of the word.

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“…For example, bats have retained, but highly honed, the mammalian (bronchoalveolar) lung. 64,[99][100][101][102] The adage that "necessity is the mother of invention" is as much relevant to natural selection as it is in the advances in human engineering. In what can be termed "evolutionary erosion", when need has justified it, gas exchangers have been deconstructed and earlier and simpler designs readopted.…”

Section: Resultsmentioning

confidence: 99%

Comparative respiratory physiology: the fundamental mechanisms and the functional designs of the gas exchangers

Maina¹

2014

OAAP

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Acquisition of molecular oxygen (O 2 ) from the external fluid media (water and air) and the discharge of carbon dioxide (CO 2 ) into the same milieu is the primary role of respiration. The functional designs of gas exchangers have been considerably determined by the laws of physics which govern the properties and the flux of gases and the physicochemical properties of the respiratory fluid media (water or air and blood). Although the morphologies of gas exchangers differ greatly, certain shared structural and functional features exist. For example, in all cases, the transfer of O 2 and CO 2 across the water/air-blood (tissue) barriers occurs entirely by passive diffusion along concentration gradients. In the multicellular organisms, gas exchangers have developed either by evagination or invagination. The arrangement, shape, and geometries of the airways and the blood vessels determine the transport and exposure of the respiratory media and, consequently, gas exchange. The thickness of the water/air-blood (tissue) barrier, the respiratory surface area, and volume of pulmonary capillary blood are the foremost structural parameters which determine the diffusing capacity of a gas exchanger for O 2 . In fish, stratified design of the gills and internal subdivision of the lungs increase the respiratory surface area: the same adaptive property is realized by different means. A surface active phospholipid substance (surfactant) lines the respiratory surface. Adaptive specializations of gas exchangers have developed to meet individual survival needs.

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A morphometric analysis of the lung of a species of bat

Cited by 45 publications

References 26 publications

The design of the avian respiratory system: development, morphology and function

The design of the avian respiratory system: development, morphology and function

Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier

Comparative respiratory physiology: the fundamental mechanisms and the functional designs of the gas exchangers

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