Reindeer ( Rangifer tarandus ) have evolved elaborate nasal turbinate structures that are perfused via a complex vascular network. These are subject to thermoregulatory control, shifting between heat conservation and dissipation, according to the animal’s needs. The three-dimensional design of the turbinate structures is essential in the sense that they determine the efficiency with which heat and water are transferred between the structure and the respired air. The turbinates have already a relatively large surface area at birth, but the structures have yet not reached the complexity of the mature animal. The aim of this study was to elucidate the structure–function relationship of the heat exchange process. We have used morphometric and physiological data from newborn reindeer calves to construct a thermodynamic model for respiratory heat and water exchange and present novel results for the simulated respiratory energy losses of calves in the cold. While the mature reindeer effectively conserves heat and water through nasal counter-current heat exchange, the nose of the calf has not yet attained a similar efficiency. We speculate that this is probably related to structure-size limitations and more favourable climate conditions during early life. The fully developed structure–function relationship may serve as inspiration for engineering design. Simulations of different extents of mucosal vascularization suggest that the abundance and pattern of perfusion of veins in the reindeer nasal mucosa may contribute to the control of temperature profiles, such that nasal cavity tissue is sufficiently warm, but not excessively so, keeping heat dissipation within limits.

中文翻译：

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成年和新生驯鹿呼吸的能量效率

驯鹿 (Rangifer tarandus) 进化出了精致的鼻甲结构，这些结构通过复杂的血管网络进行灌注。这些受体温调节控制，根据动物的需要在保温和散热之间转换。鼻甲结构的三维设计至关重要，因为它们决定了热量和水在结构和呼吸空气之间传递的效率。鼻甲在出生时就已经有较大的表面积，但结构还没有达到成熟动物的复杂程度。本研究的目的是阐明热交换过程的结构-功能关系。我们使用新生驯鹿小牛的形态测量和生理数据构建了呼吸热和水交换的热力学模型，并提供了模拟小牛在寒冷中呼吸能量损失的新结果。虽然成熟的驯鹿通过鼻腔逆流热交换有效地保存热量和水分，但小牛的鼻子还没有达到类似的效率。我们推测这可能与结构尺寸限制和早期生活中更有利的气候条件有关。充分发展的结构-功能关系可以作为工程设计的灵感。对不同程度的粘膜血管化的模拟表明，驯鹿鼻粘膜中静脉的丰度和灌注模式可能有助于控制温度分布，