Center of Applied Space Technology and Microgravity (ZARM), University of Bremen, Am Fallturm 2, 28359 Bremen, Germany.
Life Quality Engineering Interest Group, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, Jiangsu 215123, PR China.
J Biomech. 2021 Mar 30;118:110293. doi: 10.1016/j.jbiomech.2021.110293. Epub 2021 Feb 4.
Stomach is one of the most important organs in human gastro-track. To better understand the operation of human-stomach, the process of mixing and emptying of gastric contents is simulated using a numerical method. The numerical results confirm that a fast pathway is located close to the lesser curvature of the stomach when water is emptied. However, this fast pathway doesn't exist when the gastric contents are composed of water and food boluses with different properties. The muscle contractions enhance the mixing of light food boluses and water, while they have limited effects on heavy food boluses. As a result, the foods are distributed in layers; heavy food boluses are located in the bottom layer. Besides the gastric motility and high viscosity of foods, the food matrix made of heavy food particles is also important to the formation of the Magenstrasse (stomach road). The food matrix and the zone of wrinkles behave like a porous medium which has higher flow resistance to the light food particles than to the water, leading to faster emptying of water. The water is emptied along the stomach wall since the flow resistance in the stomach wrinkles is smaller than the one in the food matrix. This mechanism is supported by the numerical results, while it might interpret the phenomena observed in the experiments.
胃是人体胃肠道中最重要的器官之一。为了更好地了解人体胃的运作方式，使用数值方法模拟了胃内容物的混合和排空过程。数值结果证实，当水排空时，靠近胃小弯的位置存在快速通道。然而，当胃内容物由具有不同特性的水和食物团块组成时，这个快速通道并不存在。肌肉收缩增强了轻食物团块和水的混合，但对重食物团块的混合效果有限。因此，食物分层分布，重食物团块位于底层。除了胃动力和食物的高粘度外，由重食物颗粒组成的食物基质对于 Magenstrasse（胃路）的形成也很重要。食物基质和褶皱区域的行为就像一个多孔介质，对轻食物颗粒的流动阻力高于对水的流动阻力，导致水更快地排空。由于胃褶皱中的流动阻力小于食物基质中的流动阻力，水沿着胃壁排空。这一机制得到了数值结果的支持，同时也可以解释实验中观察到的现象。
