Exhalation Mechanics and the Evolution of Aspiration Breathing in Tetrapods

布雷纳德9419892 具有许多相互作用部分的复杂生物系统的进化机制一直吸引着生物学家 从查尔斯达尔文开始。 这项研究的目标是确定一个这样复杂的系统，用于呼吸的呼吸泵， 具有 期间改变 脊椎动物 进化 爬行动物、鸟类和哺乳动物通过吸气泵来扩张它们的肺部，在某些情况下，肋骨和横膈膜肌肉扩张胸腔并将空气吸入肺部。 呼吸空气的鱼缺乏吸气呼吸所必需的肋骨和横膈膜结构。 它们将空气吸入口腔并压缩，迫使空气进入肺部。 口腔泵仅使用头部区域的肌肉，而抽吸泵仅使用胸部和腹部区域的肌肉。 两者之间的过渡是一个复杂系统中的重大变化。 然而，一些两栖动物似乎是中间型的，用头部肌肉吸气，用身体肌肉呼气。 这项研究将 确定是否使用身体肌肉 呼气是大多数两栖动物的共同特征，因此可能是嘴泵呼吸和吸气呼吸之间的进化步骤。 压力传感器，肌肉活动传感器，空气流量传感器，和X射线视频将被用来确定通风模式的代表现存的两栖动物的所有三个订单。 研究结果将验证这样一个假设，即利用身体肌肉进行呼气是两栖动物的祖先特征，因此可能是进化的中间阶段。 的 抽吸泵。 从长远来看，这项研究将有助于确定导致复合体重组的行为，形态和神经变化的顺序 生理功能系统 一 新环境

Brainerd 9419892 The mechanism by which complex biological systems with many interacting parts evolve has engaged biologists since Charles Darwin. The goal of this research is to determine how one such complex system, the respiratory pump used for breathing, has changed during vertebrate evolution. Reptiles, birds, and mammals ventilate their lungs with an aspiration pump in which ribs, and in some cases a diaphragm muscle, expand the chest cavity and suck air into the lungs. Air-breathing fish lack the rib and diaphragm structures that are necessary for aspiration breathing. They take air into the mouth cavity and compress it, forcing air into the lungs. Mouth pumps use only muscles of the head region while aspiration pumps use only muscles of the chest and abdominal regions. The transition between the two is a significant change in a complex system. Some amphibians, however, appear to be intermediate, using head muscles for inhalation and body muscles for exhalation. This research will determine whether the use of body muscles for exhalation is common to most species of amphibians, and thus is a probable evolutionary step between mouth pump and aspiration breathing. Pressure transducers, muscle activity transducers, air flow transducers, and x-ray video will be used to determine ventilation patterns in representatives of all three orders of extant amphibians. The results will test the hypothesis that use of body muscles for exhalation is an ancestral character of the amphibians, and hence a probable intermediate stage in the evolution of the aspiration pump. In the long term, this research will aid in identifying the sequence of behavioral, morphological and neural changes that resulted in a reorganization of a complex physiological system for function in a new environment.