Lentle R G, Janssen P W M
Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand.
J Comp Physiol B. 2008 Aug;178(6):673-90. doi: 10.1007/s00360-008-0264-x. Epub 2008 Apr 10.
The physical properties of digesta may influence mixing, efficiency of digestion, and absorption within the lumen of the intestine. We review how the physical properties of digesta change during transit through the various segments of the intestine, and how their influence on flow and mixing may be modulated by peristaltic activity. We examine how, in more fluid digesta, the solid and liquid phases interact to influence flow and mixing. Similarly, how in viscid digesta, shear strength, plasticity and elasticity of contained particulate material may influence the permeation of the fluid phase and secretions into and out of the digesta bolus. The manner in which the solid and liquid phases of digesta interact in a partly gaseous environment, such as the lower bowel, to influence bolus cohesion is also examined. Those mechanisms that promote the formation of a less viscous layer at the mucosal interface to promote plug flow are reviewed, and their effect on the efficiency of mixing and digestion discussed. It is recommended that in any future work investigating the character of mixing in the intestine, a wider range of appropriate digesta properties be measured and that, in investigations of intestinal movement, perfusates with similar characteristics to digesta be used.
食糜的物理特性可能会影响肠道内的混合、消化效率及吸收。我们综述了食糜在通过肠道各段的过程中其物理特性是如何变化的，以及蠕动活动如何调节它们对流动和混合的影响。我们研究了在流动性更强的食糜中，固相和液相如何相互作用以影响流动和混合。同样，在黏性食糜中，所含颗粒物质的剪切强度、可塑性和弹性如何影响液相及分泌物进出食糜团块的渗透。我们还研究了食糜的固相和液相在诸如下段肠道这样的部分气态环境中相互作用以影响食糜团块黏聚性的方式。我们综述了那些在黏膜界面促进形成黏性较低的层以促进栓塞流的机制，并讨论了它们对混合和消化效率的影响。建议在未来任何研究肠道内混合特性的工作中，测量更广泛的合适的食糜特性，并且在肠道运动研究中，使用与食糜特性相似的灌注液。
