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.
Bile Duct Cancer
Dongyou Liu in Tumors and Cancers, 2017
The bile ducts are thin tubes of 10-12.5 cm in length that connect the liver, gallbladder, and small intestine. The bile ducts are divided into two sections: intrahepatic and extrahepatic. The intrahepatic bile ducts are small ducts located within the liver. The extrahepatic bile ducts include part of the right and left hepatic ducts outside the liver. The main function of the bile ducts is to collect bile produced in the liver and to carry the bile via the cystic duct to the gallbladder for storage and via the distal extrahepatic bile duct and through the pancreas to the small intestine. Tumors of the intrahepatic bile ducts arise from the biliary epithelium of small intrahepatic ductules or large intrahepatic ducts near the bifurcation of the right and left hepatic ducts. Tumors of the extrahepatic bile ducts occur in the common bile duct located between the point where the cystic duct joins the common hepatic duct and the ampulla of Vater.
Use of everted sacs of mouse small intestine as enzyme sources for the study of drug oxidation activities
Published in Xenobiotica, 2000
C. Emoto, H. Yamazaki, S. Yamasaki, N. Shimada, M. Nakajima, T. Yokoi
1. The use of everted sacs of the small intestine as an enzyme source for the study of the first-pass metabolism of xenobiotics by cytochrome P450s (P450, CYP) is described. Several drug oxidation activities for testosterone, chlorzoxazone, tolbutamide, bufuralol and warfarin were observed when everted sacs (1-cm segment) from different parts of mouse small intestine were incubated with an NADPH-generating system and each substrate. 2. Most of the drug hydroxylase activities resided in the upper part of mouse small intestine and these activities were much higher than those of intestinal microsomes. Drug oxidation activities decreased along the distance from the upper part of the small intestine except for warfarin hydroxylation. 3. Testosterone 6β-hydroxylation in the everted sacs exhibited the highest catalytic activities among the drug oxidations tested here. In the upper part of the small intestine, the testosterone 6β-hydroxylase activities of everted sacs subjected once to freezing and thawing were substantially decreased compared with the untreated everted sacs. 4. Testosterone 6β-hydroxylase activities in the everted sacs of the small intestine were significantly inhibited by ketoconazole. Immunoreactive proteins using anti-CYP3A antibodies were detected in the upper and middle parts of the small intestine. 5. The results demonstrated that the upper part of the mouse small intestine serves as the major site for intestinal P450 mediated first-pass metabolism. Everted sacs of the small intestine are therefore useful for the study of drug metabolism as well as of transport and absorption.
Effects of polychlorinated biphenyls on porphyrin synthesis and cytochrome p—450—dependent monooxygenases in small intestine and liver of Japanese quail
Published in Journal of Toxicology and Environmental Health, 1987
C. L. Miranda, M. C. Henderson, J.‐L. Wang, H. S. Nakaue, D. R. Buhler
The effects of acute exposure to polychlorinated biphenyls (PCBs) on porphyrin synthesis and cytochrome P‐450‐dependent monooxygenases in the small intestine and liver were studied in male Japanese quail. The birds were dosed orally with the PCB mixture, Aroclor 1242, or the individual PCB isomers, 2,4,2’,4'‐tetrachlorobiphenyl (2‐TCB) and 3,4,3’,4'‐tetrachlorobiphenyl (3‐TCB), and were killed 48 h later. All the PCB compounds caused a significant increase in porphyrin content and δ‐aminolevulinic acid synthetase (ALA‐S) activity in the small intestine and liver. Increases in porphyrins were greater in the small intestine than in liver. However, a smaller increase in ALA‐S activity occurred in the small intestine than in liver, suggesting that ALA‐S induction is not a major mechanism for the increased porphyrin content of small intestine. All the test compounds significantly increased the cytochrome P‐450 content of liver. In the small intestine, cytochrome P‐450 content was increased by Aroclor 1242 and 2‐TCB but not by 3‐TCB. The activity of 7‐ethoxyresorufin O‐deethylase, however, was increased by all test compounds in both liver and small intestine. In contrast, there was a striking difference between small intestine and liver in the induction of 7‐ethoxycoumarin O‐deethylase (ECOD) activity by Aroclor 1242. In the liver, ECOD activity was unchanged or decreased, but in the small intestine, ECOD activity increased linearly with dose. No tissue difference in ECOD activity was observed after treatment with 2‐TCB or 3‐TCB. These findings suggest that acute exposure to a given PCB results in marked differences between small intestine and liver in porphyrin metabolism and in the induction of cytochrome P‐450 isozymes and associated monooxygenases.
Effect of dietary genistein on antioxidant enzyme activities in SENCAR mice
Published in Nutrition and Cancer, 1996
Dietary administration of the soybean isoflavone genistein (50 and 250 ppm) for 30 days significantly increases the activities of antioxidant enzymes in various organs of SENCAR mice. Feeding a 250‐ppm genistein diet to SENCAR mice significantly increases the activities of catalase in small intestine, liver, and kidney, the activities of superoxide dismutase and glutathione peroxidase in skin, and the activity of glutathione reductase in skin and small intestine. Feeding 50 ppm genistein to SENCAR mice results in elevated catalase activity in the small intestine and increases glutathione‐S‐transferase activities in skin, small intestine, liver, kidney, and lung. Dietary genistein s greatest enhancement of antioxidant enzyme activities occurred in skin and small intestine. Our results suggest that dietary genistein enhances the activities of antioxidant enzymes in various organs, which may be a mechanism(s) of genistein's chemopreventive action.