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Vagal Afferent Innervation and the Regulation of Gastric Motor Function
Published in Sue Ritter, Robert C. Ritter, Charles D. Barnes, Neuroanatomy and Physiology of Abdominal Vagal Afferents, 2020
CCK is located in both endocrine cells and neurons within the GI tract. The endocrine cells are scattered evenly throughout the crypts and villi of the duodenum and proximal jejunum, with a few cells present in the ileum.70 The endocrine cells are in direct contact with the lumen of the intestinal glands and therefore will have direct access to nutrients. Fibers showing immunoreactivity for CCK are found in the mucosa, and the cell bodies are in the overlying submucosa and myenteric plexus.64 Immunoreactive fibers for CCK are rare in the stomach and there are no reports of cell bodies.
Exposure
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
Oral administration of drugs and toxins is by far the most popular route of exposure. Oral administration involves the presence of several physiological barriers, which must be penetrated or circumvented if an adequate blood concentration of the compound is to be achieved. The mucosal layers of the oral cavity, pharynx, and esophagus consist of stratified squamous epithelium, which serves to protect the upper gastrointestinal (GI) lining from the effects of contact with physical and chemical agents. Simple columnar epithelium lines the stomach and intestinal tracts, which function in digestion, secretion, and some absorption. Immediately underlying the epithelium is the lamina propria, a mucosal layer rich in blood vessels and nerves. Mucosa-associated lymphoid tissue (MALT) is layered within this level, where prominent lymphatic nodules sustain the presence of phagocytic macrophages and granulocytes. Salivary and intestinal glands contribute to the digestive process by secreting saliva and digestive juices. The submucosa, muscularis, and serosa complete the strata that form the anatomical envelope of the GI tract. Enteroendocrine and exocrine cells in the GI tract secrete hormones and in the stomach, secrete acid and gastric lipase. Tables 5.1 and 5.2 illustrate select toxic substances and routes of exposure, including dermal and ocular routes, and their suspected clinical effects.
Gastrointestinal Function and Toxicology in Canines
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
The large intestine has the same four coats as the small intestine, mucous, submucous, muscular and serous. The serous coat resembles that of the small intestine and while the muscular coat is similar to that found in the small intestine, is uniform in its thickness and consists of a thin outer longitudinal coat, a thicker inner circular layer of smooth muscle if observed to be present. The submucous coat does not differ significantly from that observed in the small intestine and small nerves, lymphatics, and blood vessels are located within it. The mucous coat, however, is significantly different from that observed in the small intestine as there are no intestinal villi and no aggregations of lymphoid tissue. However, solitary lymph nodules do exist and can be observed when viewing the dilated gut from the serosal aspect. Folds occur in the large intestine, but are only noticeable when it is highly contracted, as a minimal amount of distension is quite sufficient to remove them. These folds can be either circular or longitudinal in orientation, depending upon the type of contraction that the large intestine has undergone. The intestinal glands of the large intestine are longer and straighter than those found in the small intestine. There is also a significantly greater population of mucus-producing cells in the large intestine than found in the small intestine. A columnar epithelium lines the intestinal glands and is continuous with that which lines the mucosal surface of the lumen of the gut.
Zhizhu decoction alleviates slow transit constipation by regulating aryl hydrocarbon receptor through gut microbiota
Published in Pharmaceutical Biology, 2023
Yong Wen, Yu Zhan, Shiyu Tang, Fang Liu, Rong Wu, Pengfei Kong, Qian Li, Xuegui Tang
Histopathological analysis of the colonic tissue showed that the colonic tissue of mice in the control group had complete structures of mucosa, submucosa, muscularis and outer membrane, the mucosa was covered with single columnar epithelial cells, and a large number of intestinal glands were found in the lamina propria. However, in the model group, some areas of colonic tissue were characterized by mucosal necrosis, loss of epithelial cells in the necrotic area, necrotic of intestinal glands in the lamella propria, and the tubular structure was absent, only necrotic cell fragments and a few lymphocytes or neutrophils were observed. After treatment with all doses of ZZD and positive drugs, the damage to colonic tissue was significantly improved. The colon structure was relatively complete, the epithelial cells were arranged in a more orderly manner, and only a few intestinal glands were necrotic in the lamina propria, with slight inflammatory cell infiltration (Figure 2(A)). In addition, the thickness of mucosa tissue and muscle layers was also determined. The analysis revealed that compared with the control group, the tissue thickness was significantly reduced in the model group. However, the above effects were significantly reversed following mice treatment with different doses of ZZD (p < 0.05; Figure 2(B)).
Sinisan ameliorates colonic injury induced by water immersion restraint stress by enhancing intestinal barrier function and the gut microbiota structure
Published in Pharmaceutical Biology, 2023
Xiaoying Xu, Huimei Hu, Haizhou Zeng, Boyi Li, Qiuxiong Yin, Yupeng Jiang, Linquan Zang, Changlin Zhao, Guoqiang Qian
HE staining (Figure 1(B)) showed that the colon tissue structure of the control mice was clear, without edema or congestion, the mucosal epithelial cells were orderly arranged, the surface was smooth, the intestinal glands were normal, and there was no inflammatory cell infiltration. The WIRS mice had localized loss of colonic mucosal epithelium, wrinkled and detached, disturbed glandular structure, reduced cup cells, and inflammatory cell infiltration in the mucosal layer. Compared with the WIRS group, no edema was seen in the submucosa of the colon in the three groups of SNS pretreatment, lymphoid tissue was abundant, and inflammatory cell infiltration was reduced. Inflammatory cell infiltration increased in the SM group compared to the SL group. However, there was no inflammatory cell aggregation in the basal layer of the SH group. In comparison to the WIRS group, the DZ group had only a minor degree of inflammatory cell infiltration of the colon mucosa.
Comparative study on the gastrointestinal- and immune- regulation functions of Hedysari Radix Paeparata Cum Melle and Astragali Radix Praeparata cum Melle in rats with spleen-qi deficiency, based on fuzzy matter-element analysis
Published in Pharmaceutical Biology, 2022
Yugui Zhang, Jiangtao Niu, Shujuan Zhang, Xinlei Si, Tian-Tian Bian, Hongwei Wu, Donghui Li, Yujing Sun, Jing Jia, Erdan Xin, Xingke Yan, Yuefeng Li
The upper part of the small intestine starts from the pylorus of the stomach, and its lower part is connected with the large intestine via the ileocecal valve, which is divided into duodenum, jejunum and ileum. The HE staining results of duodenum, jejunum and ileum showed obvious injuries in SQD model compared with normal. The main reason may be related to the diarrhoea symptoms of SQD rats. Three parts of the small intestine had more crypt cells, the villi were shortened and indistinct, the villi tips were partially necrotic and detached, the villus epithelial cells were damaged and detached, and edoema was obvious. The intestinal glands were obviously degenerated, and the submucosa was slightly congested and severely oedematous, with a small amount of inflammatory cell infiltration. After treatment, the number, arrangement and morphological structure of glandular cells in each part of the small intestine were significantly improved, the length of villi increased, and edoema was relieved. In particular, HRPCM (18.9 g/kg) and ARPCM (18.9 g/kg) were more significant (Figure 10).