Furness John B
Digestive Physiology and Nutrition Laboratories, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia.
Department of Anatomy & Physiology, University of Melbourne, Parkville, VIC, Australia.
Adv Exp Med Biol. 2022;1383:165-177. doi: 10.1007/978-3-031-05843-1_16.
All life forms must gain nutrients from the environment and from single cell organisms to mammals a digestive system is present. Components of the digestive system that are recognized in mammals can be seen in the sea squirt that has had its current form for around 500my. Nevertheless, in mammals, the organ system that is most varied is the digestive system, its architecture being related to the dietary niche of each species. Forms include those of foregut or hindgut fermenters, single or multicompartment stomachs and short or capacious large intestines. Dietary niches include nectarivores, folivores, carnivores, etc. The human is exceptional in that, through food preparation (>80% of human consumption is prepared food in modern societies), humans can utilize a wider range of foods than other species. They are cucinivores, food preparers. In direct descendants of simple organisms, such as sponges, there is no ENS, but as the digestive tract becomes more complex, it requires integrated control of the movement and assimilation of its content. This is achieved by the nervous system, notably the enteric nervous system (ENS) and an array of gut hormones. An ENS is first observed in the phylum cnidaria, exemplified by hydra. But hydra has no collections of neurons that could in any way be regarded as a central nervous system. All animals more complex than hydra have an ENS, but not all have a CNS. In mammals, the ENS is extensive and is necessary for control of movement, enteric secretions and local blood flow, and regulation of the gut immune system. In animals with a CNS, the ENS and CNS have reciprocal connections. From hydra to human, an ENS is essential to life.
所有生命形式都必须从环境中获取营养物质，从单细胞生物到哺乳动物都有消化系统。哺乳动物消化系统中被认可的组成部分在海鞘中也能看到，海鞘保持当前形态已有约5亿年。然而，在哺乳动物中，变化最多样的器官系统是消化系统，其结构与每个物种的饮食生态位相关。形式包括前肠或后肠发酵者、单腔或多腔胃以及短或宽敞的大肠。饮食生态位包括食蜜动物、食叶动物、食肉动物等。人类很特殊，通过食物加工（在现代社会，超过80%的人类食物是加工食品），人类能够利用比其他物种更广泛的食物。他们是烹饪食物者，食物加工者。在简单生物的直系后代中，如海绵动物，没有肠神经系统，但随着消化道变得更加复杂，它需要对其内容物的移动和同化进行综合控制。这是由神经系统实现的，特别是肠神经系统（ENS）和一系列肠道激素。肠神经系统最早在刺胞动物门中被观察到，以水螅为代表。但水螅没有任何可被视为中枢神经系统的神经元集合。所有比水螅更复杂的动物都有肠神经系统，但并非所有动物都有中枢神经系统。在哺乳动物中，肠神经系统广泛存在，对于控制运动、肠道分泌和局部血流以及调节肠道免疫系统是必要的。在有中枢神经系统的动物中，肠神经系统和中枢神经系统相互连接。从水螅到人类，肠神经系统对生命至关重要。
