The large intestine
Paul Ong, Rachel Skittrall in Gastrointestinal Nursing, 2017
This chapter describes the embryonic development and gross anatomy of the large intestine and rectum. It explores the mechanisms governing motility within the large intestine and defaecation. The chapter also describes the processes governing absorption of water, electrolytes, vitamins and minerals. It provides the process governing the formation of faeces and defaecation. The chapter examines the physiological effects of ageing on the structure and function of the large intestine and rectum. It presents common developmental abnormalities of the large intestine and rectum. The chapter also discusses common disorders of the large intestine and rectum. It explains the pathogenesis of common colonic and rectal disorders. The large intestine starts at the point where chyme enters through the ileocaecal valve into the caecum. The histology of the large intestine shares many features of the small intestine. Large intestine receives the end products of digestion from the ileum which are predominantly water and cellulose.
Malignant tumours
Ian Talbot, Ashley Price, Manuel Salto-Tellez in Biopsy Pathology in Colorectal Disease, 2Ed, 2006
The majority of malignant tumours of the large intestine are adenocarcinomas. Other less common tumours with the same histogenesis, but with differing histological appearances, i.e. adenosquamous carcinoma and squamous carcinoma, resemble adenocarcinoma in clinical behaviour and may logically be grouped together with adenocarcinoma. With an adequate biopsy colonic carcinomas do not usually present any diagnostic difficulty, but problems may arise in deciding if small irregular fragments contain malignant glands or whether the tissue is part of an adenoma. Questions such as this and other diagnostic problems are discussed in Chapter 16.
The small intestine
Paul Ong, Rachel Skittrall in Gastrointestinal Nursing, 2017
This chapter describes the embryonic development and gross anatomy of the small intestine. It discusses the histology and physiological function of the small intestine. The chapter explores the mechanisms governing motility within the small intestine. It examines the mechanisms governing the digestion and absorption of carbohydrates, proteins, fats, minerals, water and electrolytes. The chapter provides the physiological effects of ageing on the structure and function of the small intestine. It also discusses common developmental abnormalities of the small intestine. The chapter explains the pathogenesis of common small intestine disorders. The chapter also describes common disorders of the small intestine. The structure of the small intestine is similar to other regions of the digestive tract except that it has three specialist structures which are adaptions that help define its function. The small intestine is the longest part of the digestive tract stretching from the pyloric sphincter to the ileocaecal valve where it joins the large intestine.
Expression of iron absorption genes in mouse large intestine
Published in Scandinavian Journal of Gastroenterology, 2005
Ken Takeuchi, Ingvar Bjarnason, Abas H. Laftah, Gladys O. Latunde-Dada, Robert J. Simpson, Andrew T. McKie
Objective The large intestine has been reported to have a capacity for iron absorption and expresses genes for iron absorption normally found in the duodenum. The importance and function of these genes in the large intestine are not understood. We therefore investigated the cellular localization and regulation of expression of these genes in mouse caecum and colon. Material and methods Gene expression was measured by real-time PCR using RNA extracted from iron-deficient and hypoxic mouse large intestine, compared to controls. Protein localization and regulation were measured by immunohistochemistry using frozen sections of the large intestine from the same mice. Results Dcytb (duodenal ferric reductase) was expressed at very low levels in the large intestine, compared to the duodenum, while Ireg1 and DMT1 were expressed at significant levels in the large intestine and were increased in iron-deficient caecum, proximal and distal colon, with the most significant increases seen in the distal colon. Hypoxia increased Ireg1 expression in the proximal colon. Immunohistochemistry detected significant levels of only IREG1, which was localized to the basolateral membrane of colonic epithelial cells. Conclusions Iron absorption genes were expressed at lower levels in mouse caecum and colon than in the duodenum. They are regulated by body iron requirements. Colonic epithelial cells express basolateral IREG1in the same fashion as in the duodenum and this protein could regulate colonic epithelial cell iron levels.
Comparative Assessment of Intestinal Transport of Hydrophilic Drugs Between Small Intestine and Large Intestine
Published in Drug Delivery, 1997
Hiroaki Yuasa, Kenji Matsuda, Yukie Kimura, Naomi Soga, Jun Watanabe
Intestinal passive transport of several hydrophilic drugs (and probe compounds) was examined in the large intestine (colon), in comparison with that in the small intestine, in an effort to obtain basic information for developing rational colonic drug delivery strategies. The drugs tested were polyethylene glycol (PEG 900), L-glucose, D-xylose, 5-fluorouracil (5-FU) and urea. In everted intestinal sacs, the uptake of every drug was larger in the small intestine than in the large intestine, although by various extents. The uptake of urea was larger than those of D-xylose and L-glucose in both the small intestine and large intestine and associated with a larger large intestine (LI)/small intestine (SI) uptake ratio. Assuming that passive transport via the paracellular route (or aqueous pore) is predominant for them, the large intestine may have smaller paracellular (or aqueous) pores, restricting the transport of those monosaccharides compared with smaller molecules such as urea by a larger extent in the large intestine than in the small intestine. The passive transport of 5-FU was significantly larger than those of the monosaccharides in both the small intestine and large intestine and associated with a larger LI/SI uptake ratio, even though 5-FU has a molecular weight close to that of the monosaccharides. 5-FU may be transported predominantly by transcellular diffusion, because its oil-to-water partition coefficient is about 200 times larger than those of the monosaccharides. Although transport mechanisms, including transport pathways, are yet to be fully clarified, drugs with physicochemical properties similar to those of 5-FU or urea may be more feasible for colonic drug delivery than those with physicochemical properties similar to those of monosaccharides.
Development of Peristaltic Crawling Robot with Artificial Rubber Muscles Attached to Large Intestine Endoscope
Published in Advanced Robotics, 2012
Taro Nakamura, Yuya Hidaka, Masato Yokojima, Kazunori Adachi
The number of large intestine cancer patients has been increasing steadily. An endoscope can be used to diagnose as well as to treat the diseased part of the intestine. A large intestine endoscope is used mainly to examine cancer of the large intestine. However, many doctors have problems handling an endoscope. To resolve this issue, there is demand for a robotic application to assist in inserting the endoscope and straightening the slack from the intestine. We propose a robot that imitates the peristaltic crawling of an earthworm and uses an artificial rubber muscle as an actuator. By attaching the robot to an existing endoscope, it will be possible to move the endoscope forward and pull up the intestine simultaneously, while retaining the functions of the existing endoscope. In this paper, we test the forward and pulling movements of a sliding-air-tube robot in a large intestine of model to evaluate its performance. From these experiments, the robot equipped with the endoscope of 11 mm in the diameter can be moved at the speed that satisfies it. Further, air-emit function is added to this robot and its performance in the large intestine of a dead swine is evaluated. Result of accomplishing experiment by using imitation of endoscope of 8 mm, this robot showed that it had the ability to move the endoscope.