Disorders of the small intestine and vermiform appendix
Alfred Cuschieri, George Hanna in Essential Surgical Practice, 2015
Anatomy The small intestine is divided into three anatomical portions: duodenum, jejunum and ileum. However, in surgery, the duodenum, which forms the first 25 cm, is considered with the stomach because of various pathologies which affect both organs, such as peptic ulceration. At postmortem the average length of the small intestine in situ is about 7 m, with a reported range of 4.3-10.3 m when the measurement is made along the antimesenteric border. These estimates have to be regarded as approximate and are certainly not exact in view of the distensibility of the small intestine, the flaccid state after death and indeed the method of measurement (usually by tape) used in these postmortem studies. The length of the intestine (less the duodenum) when measured along its attached or mesenteric border, is only 4.6 m.
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.
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.
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.
Distribution of Disaccharidases, Alkaline Phosphatase, and Some Intracellular Enzymes along the Human Small Intestine
Published in Scandinavian Journal of Gastroenterology, 1975
N.-G. Asp, E. Gudmand-Höyer, B. Andersen, N.-O. Berg, A. Dahlqvist
Asp, N.-G., Gudmand-Höyer, E., Andersen, B., Berg, N.-O. & Dahlqvist, A. Distribution of disaccharidases, alkaline phosphatase, and some intracellular enzymes along the human small intestine. Scand. J. Gastroent. 1975, 10, 647-651. The longitudinal distribution of various enzymes along the human small intestine was studied by analysis of biopsies from different parts of the small intestine, obtained from 13 patients during shunt-operation for severe obesity. Alkaline phosphatase and 3 glycolytic enzyme activities studied were rather uniformly distributed along the small intestine. Acid β-galactosidase and hetero β-galactosidase activities were highest in the proximal small intestine with a gradual decline throughout the intestine. The activity in the distal ileum was about half of the maximum activity. Maltase, isomaltase, sucrase, and trehalase activity had a broad maximum in the proximal and middle small intestine with a rather sharp decrease in the distal ileum. Lactase activity had a more pronounced maximum in the middle intestine with a pronounced decrease towards the proximal and distal ends. The disaccha-ridase activities in surgical biopsies taken 5 cm distal to the ligament of Treitz were about 10% higher than in peroral biopsies taken just at the ligament.
Atresia of the small intestine in lambs and calves
Published in New Zealand Veterinary Journal, 1978
W.T. Clark, J.E. Cox, M.J. Birtles
The literature on congenital atresia of the small intestine in calves and lambs is briefly reviewed. Lesions resembling those described in clinical cases were produced experimentally by occluding the blood supply to the intestine in foetal lambs. Histological examination of the small intestine proximal to the induced atresia revealed a reduction in the length of the villi with distension of blood vessels and lymphatics. Distal to the lesion the intestine had a normal histological structure.