Abstract:
:A braced framework of tubular struts, in the walls and air spaces of frog lungs, suspends the respiratory surface and holds the lung open at zero transmural pressure withstanding imploding forces created by abdominal viscera, much as would the supports of a bell tent. The struts are tubes, having a larger second moment of area than do solid struts of the same cross-sectional area, and so are stronger, and contain pulmonary vessels within a flexible wall. The orthogonal arrangement of the struts in the framework, explained in part by Maxwell's Lemma and Michell's Theorem, strengthens the framework and minimizes its weight; orthogonality is maintained as the lungs change size. A model is presented, in which a frog might control pre- and post-pulmonary vascular resistances and, hence, blood volume in the struts, without compromising pulmonary perfusion. Such adjustments could vary the area of lung and the extent of perfused capillaries exposed to pulmonary gas, helping match the lung's surface area, weight and metabolic load to activity.
journal_name
Bull Math Bioljournal_title
Bulletin of mathematical biologyauthors
Lawry Jdoi
10.1006/bulm.1999.0104subject
Has Abstractpub_date
1999-07-01 00:00:00pages
683-700issue
4eissn
0092-8240issn
1522-9602journal_volume
61pub_type
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