The human gastrointestinal tract harbors most of the microbial cells inhabiting the body, collectively known as the microbiota. These microbes have several implications for the maintenance of structural integrity of the gastrointestinal mucosal barrier, immunomodulation, metabolism of nutrients, and protection against pathogens. Dysfunctions in these mechanisms are linked to a range of conditions in the gastrointestinal tract, including functional gastrointestinal disorders, ranging from irritable bowel syndrome, to functional constipation and functional diarrhea. Irritable bowel syndrome is characterized by chronic abdominal pain with changes in bowel habit in the absence of morphological changes. Despite the high prevalence of irritable bowel syndrome in the global population, the mechanisms responsible for this condition are poorly understood. Although alterations in the gastrointestinal microbiota, low-grade inflammation and immune activation have been implicated in the pathophysiology of functional gastrointestinal disorders, there is inconsistency between studies and a lack of consensus on what the exact role of the microbiota is, and how changes to it relate to these conditions. The complex interplay between host factors, such as microbial dysbiosis, immune activation, impaired epithelial barrier function and motility, and environmental factors, including diet, will be considered in this narrative review of the pathophysiology of functional gastrointestinal disorders.

人的胃肠道具有居住在人体中的大多数微生物细胞，统称为微生物群。这些微生物对于维持胃肠道粘膜屏障的结构完整性，免疫调节，营养物质的代谢以及对病原体的保护具有若干意义。这些机制的功能障碍与胃肠道的一系列疾病有关，包括功能性胃肠道疾病，从肠易激综合征到功能性便秘和功能性腹泻。肠易激综合征的特征是慢性腹痛，在没有形态学改变的情况下肠习性改变。尽管全球人群中肠易激综合征的患病率很高，但导致这种情况的机制仍知之甚少。尽管胃肠道微生物群的改变，低度炎症和免疫激活与功能性胃肠道疾病的病理生理有关，但研究之间并不一致，并且对于微生物菌群的确切作用及其变化缺乏共识。与这些条件有关。在对功能性胃肠疾病的病理生理学的叙述性回顾中，将考虑宿主因素之间的复杂相互作用，例如微生物功能障碍，免疫激活，上皮屏障功能和运动受损以及环境因素（包括饮食）。在研究之间存在不一致的地方，并且在微生物群的确切作用是什么以及其变化如何与这些条件有关方面缺乏共识。在对功能性胃肠疾病的病理生理学的叙述性回顾中，将考虑宿主因素之间的复杂相互作用，例如微生物功能障碍，免疫激活，上皮屏障功能和运动受损以及环境因素（包括饮食）。在研究之间存在不一致的地方，并且在微生物群的确切作用是什么以及其变化如何与这些条件有关方面缺乏共识。在对功能性胃肠疾病的病理生理学的叙述性回顾中，将考虑宿主因素之间的复杂相互作用，例如微生物功能障碍，免疫激活，上皮屏障功能和运动受损以及环境因素（包括饮食）。