Jensen Bjarke, H Smit Theodoor
Department of Medical Biology, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands.
J Cardiovasc Dev Dis. 2018 Sep 8;5(3):46. doi: 10.3390/jcdd5030046.
That form and function are related is a maxim of anatomy and physiology. Yet, form-function relations can be difficult to prove. Human subjects with excessive trabeculated myocardium in the left ventricle, for example, are diagnosed with non-compaction cardiomyopathy, but the extent of trabeculations may be without relation to ejection fraction. Rather than rejecting a relation between form and function, we may ask whether the salient function is assessed. Is there a relation to electrical propagation, mean arterial blood pressure, or propensity to form blood clots? In addition, how should the extent of trabeculated muscle be assessed? While reviewing literature on trabeculated muscle, we applied Tinbergen's four types of causation-how does it work, why does it work, how is it made, and why did it evolve-to better parse what is meant by form and function. The paper is structured around cases that highlight advantages and pitfalls of applying Tinbergen's questions. It further uses the evolution of lunglessness in amphibians to argue that lung reduction impacts on chamber septation and it considers the evolution of an arterial outflow in fishes to argue that reductions in energy consumption may drive structural changes with little consequences to function. Concerning trabeculations, we argue they relate to pumping function in the embryo in the few weeks before the onset of coronary circulation. In human fetal and postnatal stages, a spectrum of trabeculated-to-compact myocardium makes no difference to cardiac function and in this period, form and function may appear unrelated.
形态与功能相关是解剖学和生理学的一条准则。然而，形态 - 功能关系可能难以证明。例如，左心室小梁化心肌过多的人类受试者被诊断为致密化不全型心肌病，但小梁化程度可能与射血分数无关。与其否定形态与功能之间的关系，我们或许应该问是否评估了显著的功能。它与电传导、平均动脉血压或形成血栓的倾向有关系吗？此外，应如何评估小梁化肌肉的程度呢？在回顾有关小梁化肌肉的文献时，我们应用了廷伯根的四种因果关系类型——它是如何工作的、为什么会这样工作、它是如何形成的以及为什么会进化——来更好地剖析形态和功能的含义。本文围绕一些案例展开，这些案例突出了应用廷伯根问题的优点和缺陷。它还利用两栖动物无肺现象的进化来论证肺的退化会影响心室间隔，并且考虑鱼类动脉流出的进化来论证能量消耗的减少可能会推动结构变化而对功能影响不大。关于小梁化，我们认为在冠状动脉循环开始前的几周胚胎期，它们与泵血功能有关。在人类胎儿期和出生后阶段，一系列小梁化心肌到致密心肌的情况对心脏功能并无影响，在此期间，形态和功能可能看起来没有关联。
