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Physiology of the Human Biliary System
Published in Wenguang Li, Biliary Tract and Gallbladder Biomechanical Modelling with Physiological and Clinical Elements, 2021
The GB has two major functions: (1) bile storage and (2) bile modification. Although liver cells produce around 1 litre of bile each day, the sphincter of Oddi remains closed until chyme enters the duodenum. In this case, bile cannot flow along the CBD; it has to enter the CD for storage within the expandable GB. This kind of bile movement is named as refilling. When bile stays in the GB, much of the water in bile is absorbed, and bile salts and other components become increasingly concentrated. Consequently, the composition of bile gradually changes. Although bile is secreted continuously, bile release into the duodenum occurs only under the stimulation of cholecystokinin (CCK). In the absence of CCK, the sphincter of Oddi is closed and bile produced by the liver reaches the GB through both the CHD and the CD. When chyme enters the duodenum, CCK is released, but the amount secreted highly depends on the amount of lipids contained in chyme. CCK relaxes the sphincter of Oddi and stimulates contractions in the walls of the GB. These contractions push bile into the duodenum (small intestine) (Martini 2001). This process is called emptying.
Regulation of Blood Glucose
Published in Robert B. Northrop, Endogenous and Exogenous Regulation and Control of Physiological Systems, 2020
The description of glucoregulation begins by first discussing the protein hormone insulin. Insulin is produced by the pancreatic beta cells in response to elevated plasma (blood) glucose concentration. The release rate of insulin into the portal circulation can be modeled by the system shown in Figure 7.2. A fast, rectified, single time constant path is in parallel with a slow, two-pole lag path. The former path describes the dynamics of immediate, stored insulin release in response to a sudden increase in blood glucose concentration [BG]. The two-pole, slow path with the transport lag term models the metabolic activation of beta cells to synthesize new insulin for release. At a normal, resting [BG] = 90 mg/dl, the beta cells secrete insulin at a rate QI = 10 ng/min/kg body weight of insulin. At very high [BG] > 500 mg/dl, QI saturates at about 20 times normal, or 200 ng/min/kg body weight.59 A number of substances associated with eating other than [BG] increase the insulin secretion rate. These substances include the amino acids lysine and arginine as well as the gastrointestinal hormones gastrin, secretin, cholecystokinin, and gastric inhibitory peptide. Also, the hormones glucagon, Cortisol, and growth hormone increase QI or potentiate the action of [BG] on insulin secretion.59
Clinical Effects of Pollution
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
Impaired gallbladder bile acid production977 and biliary cirrhosis, an inflammatory liver disease characterized by obstruction of the bile duct,978 have been shown to co-occur with celiac disease. CYP enzymes are crucial in the production of bile acids.979 An obiligatory CYP enzyme in bile acid synthesis, CYP27A, has been identified as being identical to the mitochondrial vitamin D3 activating enzyme.980 In Kemppainen et al.,981 64% of men and 71% of women with celiac disease were found to be vitamin D3 deficient, manifested as low spinal bone mineral density. Celiac disease is associated with impaired gall bladder function and decreased pancreatic secretions982,983 along with recurrent pancreatitis.984 Abnormalities in bile acid secretion have been found in children suffering from celiac disease.985 Celiac patients exhibit abnormally low synthesis of cholecystokinin,986 but it has also become apparent that the gall bladder is less responsive to stimulation of contraction by cholecystokinin.982 A reversible defect of gallbladder emptying and cholecystokinin release has been identified in association with celiac disease.987 These pathologies may be related to impaired CYP enzyme activity induced by glyphosphate.
Patient-specific fluid–structure interaction model of bile flow: comparison between 1-way and 2-way algorithms
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Alex G. Kuchumov, Vasily Vedeneev, Vladimir Samartsev, Aleksandr Khairulin, Oleg Ivanov
The motor functions of the gallbladder and biliary tract are closely integrated with the rest of the digestive system by neurohormonal mechanisms that include the vagus and splanchnic nerves and various hormones among them cholecystokinin (CCK). The gallbladder contracting and discharging bile into the duodenum during fasting and digestive periods is controlled by CCK release (Çerçi et al. 2009).