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Cheon HL, Kizilova N, Flekkøy EG, Mason MJ, Folkow LP, Kjelstrup S. The nasal cavity of the bearded seal: An effective and robust organ for retaining body heat and water. J Theor Biol 2024; 595:111933. [PMID: 39260737 DOI: 10.1016/j.jtbi.2024.111933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 08/19/2024] [Accepted: 08/29/2024] [Indexed: 09/13/2024]
Abstract
We report the effects of varying physiological and other properties on the heat and water exchange in the maxilloturbinate structure (MT) of the bearded seal (Erignathus barbatus or Eb) in realistic environments, using a computational fluid dynamics (CFD) model. We find that the water retention in percent is very high (about 90 %) and relatively unaffected by either cold (-30 °C) or warm (10 °C) conditions. The retention of heat is also high, around 80 % . Based on a consideration of entropy production by the maxilloturbinate system, we show that anatomical and physiological properties of the seal provide good conditions for heat and water exchange at the mucus lining in the seal's nasal cavity. At normal values of tidal volume and maxilloturbinate (MT) length, the air temperature in the MT reaches the body temperature before the air has left the MT channels. This confers a safety factor which is expected to be helpful in exercise, when ventilation increases.
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Affiliation(s)
- Hyejeong Lee Cheon
- Department of Physics, Norwegian University of Science and Technology, NTNU, Høgskoleringen 5, Trondheim, NO-7491, Norway
| | - Nataliya Kizilova
- PoreLab, Department of Physics, Norwegian University of Science and Technology, NTNU, Høgskoleringen 5, Trondheim, NO-7491, Norway; Institute of Aeronautics and Applied Mechanics, Warsaw University of Technology, Nowowiejska 24, Warsaw, 00-665, Poland
| | - Eirik G Flekkøy
- PoreLab, Department of Physics, University of Oslo, Sem Sælandsvei 24, Oslo, N-0371, Norway; PoreLab, Department of Chemistry, Norwegian University of Science and Technology, NTNU, Høgskoleringen 5, Trondheim, NO-7491, Norway
| | - Matthew J Mason
- Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK
| | - Lars P Folkow
- Department of Arctic and Marine Biology, UiT - the Arctic University of Norway, Framstredet 39, Tromsø, 9019, Norway
| | - Signe Kjelstrup
- PoreLab, Department of Chemistry, Norwegian University of Science and Technology, NTNU, Høgskoleringen 5, Trondheim, NO-7491, Norway.
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Cheon HL, Kjelstrup S, Kizilova N, Flekkøy EG, Mason MJ, Folkow LP. Structure-function relationships in the nasal cavity of Arctic and subtropical seals. Biophys J 2023; 122:4686-4698. [PMID: 38101406 PMCID: PMC10754691 DOI: 10.1016/j.bpj.2023.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/04/2023] [Accepted: 11/15/2023] [Indexed: 12/17/2023] Open
Abstract
The heating and moistening of inhaled air, and the cooling and moisture removal from exhaled air, are crucial for the survival of animals under severe environmental conditions. Arctic mammals have evolved specific adaptive mechanisms to retain warmth and water and restrict heat loss during breathing. Here, the role of the porous turbinates of the nasal cavities of Arctic and subtropical seals is studied with this in mind. Mass and energy balance equations are used to compute the time-dependent temperature and water vapor profiles along the nasal passage. A quasi-1D model based on computed tomography images of seal nasal cavities is used in numerical simulations. Measured cross-sectional areas of the air channel and the perimeters of the computed tomography slices along the nasal cavities of the two seal species are used. The model includes coupled heat and vapor transfer at the air-mucus interface and heat transfer at the interfaces between the tissues and blood vessels. The model, which assumes constant blood flow to the nose, can be used to predict the temperature of the exhaled air as a function of ambient temperature. The energy dissipation (entropy production) in the nasal passages was used to measure the relative importance of structural parameters for heat and water recovery. We found that an increase in perimeter led to significant decreases in the total energy dissipation. This is explained by improved conditions for heat and water transfer with a larger complexity of turbinates. Owing to differences in their nasal cavity morphology, the Arctic seal is expected to be advantaged in these respects relative to the subtropical seal.
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Affiliation(s)
- Hyejeong L Cheon
- PoreLab, Department of Physics, Norwegian University of Science and Technology, NTNU, Trondheim, Norway
| | - Signe Kjelstrup
- PoreLab, Department of Chemistry, Norwegian University of Science and Technology, NTNU, Trondheim, Norway.
| | - Nataliya Kizilova
- PoreLab, Department of Physics, Norwegian University of Science and Technology, NTNU, Trondheim, Norway; V.N. Karazin Kharkov National University, Kharkov, Ukraine
| | - Eirik G Flekkøy
- PoreLab, Department of Physics, University of Oslo, Oslo, Norway
| | - Matthew J Mason
- Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, UK
| | - Lars P Folkow
- Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø, Norway
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