Geist N R
Department of Zoology, Oregon State University, Corvallis, 97331-2914, USA.
Physiol Biochem Zool. 2000 Sep-Oct;73(5):581-9. doi: 10.1086/317750.
Nasal respiratory turbinates are complex, epithelially lined structures in nearly all birds and mammals that act as intermittent countercurrent heat exchangers during routine lung ventilation. This study examined avian respiratory turbinate function in five large bird species (115-1,900 g) inhabiting mesic temperate climates. Evaporative water loss and oxygen consumption rates of birds breathing normally (nasopharyngeal breathing) and with nasal turbinates experimentally bypassed (oropharyngeal breathing) were measured. Water and heat loss rates were calculated from lung tidal volumes and nasal and oropharyngeal exhaled air temperatures (T(ex)). Resulting data indicate that respiratory turbinates are equally adaptive across a range of avian orders, regardless of environment, by conserving significant fractions of the daily water and heat budget. Nasal T(ex) of birds was compared to that of lizards, which lack respiratory turbinates. The comparatively high nasal T(ex) of the lizards in similar ambient conditions suggests that their relatively low metabolic rates and correspondingly reduced lung ventilation rates may have constrained selection on similar respiratory adaptations.
鼻腔呼吸鼻甲是几乎所有鸟类和哺乳动物中由上皮组织构成的复杂结构，在常规肺通气过程中充当间歇性逆流热交换器。本研究考察了栖息在温带湿润气候中的五种大型鸟类（体重115 - 1900克）的鸟类呼吸鼻甲功能。测量了正常呼吸（鼻咽呼吸）以及实验性绕过鼻甲呼吸（口咽呼吸）的鸟类的蒸发失水率和耗氧率。根据肺潮气量以及鼻腔和口咽呼出气体温度（T(ex)）计算出水和热的损失率。所得数据表明，无论环境如何，呼吸鼻甲在一系列鸟类目中都具有同等的适应性，因为它们能节省大量的每日水和热预算。将鸟类的鼻腔T(ex)与缺乏呼吸鼻甲的蜥蜴的鼻腔T(ex)进行了比较。在相似环境条件下，蜥蜴相对较高的鼻腔T(ex)表明，它们相对较低的代谢率以及相应降低的肺通气率可能限制了对类似呼吸适应性的选择。
