Liver bile secretion

Before leaving the liver, a large proportion of the bile acids are activated with CoA and then conjugated with the amino acids g/ycine or taurine (2 cf A). In this way, cholic acid gives rise to glycocholic acid and taurocholic acid. The liver bile secreted by the liver becomes denser in the gallbladder as a result of the removal of water (bladder bile 3). 

Bile is produced continuously by the liver bile salts are secreted by the hepatocytes and the water, sodium bicarbonate, and other inorganic salts are added by the cells of the bile ducts within the liver. The bile is then transported by way of the common bile duct to the duodenum. Bile facilitates fat digestion and absorption throughout the length of the small intestine. In the terminal region of the ileum, the final segment of the small intestine, the bile salts are actively reabsorbed into the blood, returned to the liver by way of the hepatic portal system, and resecreted into the bile. This recycling of the bile salts from the small intestine back to the liver is referred to as enterohepatic circulation. 

The return of the bile salts to the liver from the small intestine is the most potent stimulus of bile secretion. In fact, these bile salts may cycle two to five times during each meal. The intestinal hormone secretin, which is released in response to acid in the duodenum, enhances aqueous alkaline secretion by the liver. Secretin has no effect on the secretion of bile salts. During the cephalic phase of digestion, before food even reaches the stomach or intestine, parasympathetic stimulation, by way of the vagus nerve, promotes bile secretion from the liver. 

Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile adds and salts, cholesterol, and electrolytes. It aids digestion of fats in the duodenum. [NIH]... 

Bile acids aid in the digestion of dietary lipids. They are made in the liver and secreted into the small intestine in the bile where they emulsify lipids. 

As partially digested proteins pass through the duodenum on the way to the intestine, they mix with secretions from both the pancreas and the liver (bile). 

Liver disease or injury may impair bile secretion and thereby lead to accumulation of certain drugs, for example probenecid, digoxin, and diethylstilbestrol. Impairment of liver function can lead to decreased rates of both drug metabolism and secretion of drugs into bile. These two processes, of course, are frequently interrelated, since many drugs are candidates for biliary secretion only after appropriate metabolism has occurred. 

Well absorbed from the G1 tract. Protein binding 26%. Undergoes extensive first-pass liver metabolism to active metabolite. Eliminated via bile, secreted into G1 tract via intestine, and excreted in urine. Removed by hemodialysis. Half-life 3-4 hr metabolite, 8-13 hr. 

Certain drugs are excreted in urine only in small amounts but appear in high concentrations in the bile for example, erythromycin, novobiocin, tetracycline, phenolphthalein etc. The abnormality or any disease related to liver may impair bile secretion which can lead to the accumulation of certain drugs like probenecid, digoxin etc. This can also lead to decreased drug metabolism and decreased rates of secretion of drugs into bile. 

Carduus marianus L. Flavonlignans (silymarin), poly acetylenes.99 Protect the liver, stimulate secretion of bile, increase breast-milk production. An antidepressant. 

This formula can clear heat, transform dampness and reduce jaundice. It is used to treat damp-heat in the Spleen, Stomach, Liver and Gall Bladder which obstructs bile secretion. The manifestations are jaundice with a fresh tangerine color, slight abdominal distension, thirst and difficult urination, a yellow, sticky tongue coating and a deep, rapid pulse. 

As well as the above-mentioned functions, this herb has other functions that can be used as a reference in selecting herbs in a formula. It is an aromatic herb, and is able to penetrate damp-heat, clear damp-heat and promote bile secretion. It can be used as deputy in a formula when there is damp-heat in the Upper- and Middle-Jiao, the symptoms of which are fullness in the chest and epigastric region, jaundice and reduced appetite, such as in malaria and hepatitis. In addition, Yu Jin can spread the Liver-Qi, clear the Liver-heat and eliminate irritability. It can be selected to treat headache and a tight sensation in the chest caused by Qi and blood stagnation and damp-heat obstruction. 

Bile is an aqueous solution of bile salts, inorganic salts, bile pigments, fats, cholesterol, and others. The physiology of bile secretion is not simple, as it involves the active excretion of organic solutes from the blood to the bile. Bile is collected directly from the liver cells through separate channels, without being mixed with blood. The liver cell membrane incorporates extremely fine passages that permit bile secretion. 

There are a number of factors that affect the absorption of foreign compounds from the gut or their disposition one factor, which is of particular importance, is the aqueous solubility of the compound in the nonionized form. With very lipid-soluble compounds, water solubility may be so low that the compound is not well absorbed (Table 2), because it is not dispersed in the aqueous environment of the gastrointestinal tract. In relation to this, a factor of particular importance in absorption of chemicals from the gut is the presence of bile, which is produced in the liver and secreted into the small intestine. This contains detergent-like substances, which will facilitate the dispersal of lipid-soluble chemicals in the aqueous medium of the intestine. 

Impaired liver function or blocked bile secretion causes bilirubin to leak from the liver into the blood, resulting in a yellowing of the skin and eyeballs, a con-... 

Dietary cholesterol, together with triacylglycerols, is absorbed from the intestinal tract and enters the large lipoprotein chylomicrons (see Fig. 21-1). Absorption of cholesterol is incomplete, usually amounting to less than 40% of that in the diet. Absorption requires bile salts and is influenced by other factors.186 As it is needed cholesterol is taken from the plasma lipoproteins into cells by endocytosis. Much of the newly absorbed cholesterol is taken up by the liver. The liver also secretes cholesterol, in the form of esters with fatty acids, into the bloodstream. 

FIG. 1 Movement of cholesterol (CHOL) and bile acids (BA) between the liver and small intestine. CHOL and BA in the liver are secreted into the gallbladder where they are stored temporarily until a fat-containing meal causes their secretion into the intestinal lumen. BA are absorbed with high efficiency (95%) and are recycled back to the liver via the hepatic portal vein. CHOL is absorbed less efficiently (50-60%) and must be incorporated into lipoproteins (chylomicrons) for transport back to the fiver via the systemic circulation. Accumulation of CHOL in the liver can promote secretion of CHOL into plasma, thus increasing LDL-CHOL concentration. Loss of CHOL and BA in feces represents the primary route of CHOL elimination from the body. 

The extract from Berberis vulgaris as well as that of the alkaloids berberine, oxyacanthine, berbamine, jatrorrhizine, and columbamine stimulate secretion of the bile (480, 481). The strongest effect was produced by berberine, followed by berbamine and oxyacanthine. The choleretic effect of berberine was also studied by Vartazaryan (482). Turova et al. (483) examined the effect of berberine on 225 patients with chronic cholecystitis. Peroral doses of 5-20 mg three times daily before meals over a period of 24-48 hours caused disappearance of the clinical symptoms, decrease in the level of bilirubin, and increase in the bile volume in the gall bladder. Berberine also had a favorable effect in patients with toxic hepatitis induced by intoxication. No side effects were observed on the liver functions or the blood composition. The effect of berberine on the stimulation of bile secretion was also studied by Samaj et al. (484). 

Bile salts are produced in the liver and secreted into the intestinal lumen forming mixed micelles with lecithin, monoglycerides, fatty adds and cholesterol. Because... 

The view that this is true net biosynthesis of fibrinogen is supported by a variety of ancillary observations. Fibrinogen biosynthesis is suppressed in the presence of metabolic analogs, such as L-ethionine and puromycin, most markedly by the latter in spite of the maximal stimulus for production. Mitomycin C, which is believed to interfere with biosynthetic processes in the nucleus, also caused some suppression of fibrinogen biosynthesis. The isolated perfused liver in the presence of any of the three inhibitors used continues to function in an apparently normal manner in terms of bile secretion, linear urea production, amino acid oxidation, and glucose utilization. The effects of these inhibitors on the biosynthesis of the other plasma proteins will be described elsewhere. 

If the c is absorbed by the liver but not secreted into the bile ducts, there is probably a complete obstruction of the ducts exiting the liver. When the c fails to appear in the gallbladder but is detected in the intestine, there is probably an obstruction of the cystic duct leading to and from the gallbladder. Finally, if the c appears outside the liver, bile ducts, gallbladder or intestine, there is probably a bile leak from the bile ducts or gallbladder. 

The turmeric rhizome is a main ingredient of curry powder. It gives color and flavor to food, and it has aromatic, stimulant, and carminative properties. This herb is used traditionally in India to treat biliary disorders, anorexia, cough, diabetic wounds, liver disorders, rheumatism, and sinusitis and in China for abdominal pains and jaundice. Turmeric has a protective effect on the liver, stimulates bile secretion in animals, and is recommended for use in liver disorders. 

The bile canaliculus is formed as a bile capillary by means of a groove-like canal in the intercellular space, bounded by 2 adjacent liver cells. The bile canaliculi have no walls of their own, but are surrounded by a special zone of the cell membrane (so-calledpericanalicular ectoplasm). Their diameter amounts to 0.5-1.0 pm. They are interconnected and form an extensive polygonal network. The surface area of the bile capillaries is increased by microvilli, which show great functionally determined variability. The canalicular membrane constitutes 10% of the total plasma membrane in the hepatocytes. Similar to the pericanalicular ectoplasm, the hepatocytes contain contractile microfilaments and other components of the cytoskel-eton. These canaliculi are supplied with carrier proteins and enzymes to control bile secretion. (2,34)... 

This volume of secretion is supplemented in the ductules by ca. 150 ml ductular bile, resulting in a daily production of ca. 600 ml. Bile formation is lower at night than during the day. The most important constituents of the so-called liver bile are the bile acids, phospholipids, proteins, cholesterol and bilirubin. The term bile lipids includes cholesterol, bile salts and phospholipids. The manner in which cholesterol is excreted into the gall bladder is not yet known, nor have any cholesterol-specific transport systems been detected. Cholesterol is primarily broken down into bile acids, (see above) (s. tab. 3.5)... 

Crawford, XM. Role of vesicle-mediated transport pathways in hepatocellular bile secretion. Semin. Liver Dis. 1996 16 169-189... 

Medications metabolized by the liver are secreted into bile. Bile enters the intestine and is eliminated in feces. Fat-soluble medications are reabsorbed from bile into the bloodstream and returned to the liver to be metabolized and eliminated by the kidneys. This process is called the enterohepatic cycle. Medications that are not metabolized by the liver are eliminated by the lungs at a rate that corresponds to the patient s respiration rate. These are volatile medications, such as anesthetics and medications that are metabolized to C02 and H20. Side effects such as rashes and skin reaction are commonly seen at sweat and salivary glands. For example, a patient may report tasting the medication. Medication excreted into saliva is eventually swallowed, reabsorbed, and... 

The rate of mercury excretion was also slower in younger animals (7 or 15 days) than in older animals (24 and 56 days) (Thomas et al. 1982). This age-dependent difference in the rate of mercury excretion may reflect differences in the sites of mercury deposition (i. e., hair, red blood cells, skin). In neonatal rats, the excretion of methylmercury is longer than in adult rats because of the inability of the neonatal liver to secrete the toxicant into the bile. Therefore, the immaturity of the transport system in neonatal rats affects the elimination of mercury. 

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