One common consequence of gall stones is blockage of the common bile duct. Descr

Question

One common consequence of gall stones is blockage of the common bile duct. Describe why blockage of the common bile duct leads to impaired absorption of fat-soluble vitamins. (What would be missing?)

Symptoms of heartburn are usually caused by acid regurgitating from the stomach into the esophagus. Why does acid irritate the esophagus but not the stomach. (Answer should include a discussion of both the esophagus & stomach. Provide details- simply stating that the stomach is “protected” isn’t adequate.)

Explanation / Answer

Bile is secreted by the liver and stored in the gallbladder. Bile is involved in the emulsification of fats. Bile increases the absorption of fats and fat-soluble vitamins such as A, D, E and K. It also serves as the excretion route for bilirubin. Formation of gallstones blocks the bile duct. In such a case, fats can not be emulsified resulting in malabsorption.

Stomach parietal cells produce HCl which performs two functions. The acid helps in digestion of food. It also provides optimum pH for the action of other digestive enzymes. The acid produced by parietal cells does not damage the mucosal layer. This is due to the maintenance of almost neutral pH in the parietal cells by transport of bicarbonate, chloride and K+ ions.
CO2 + H2O ------> H2CO3 ------> H+ + HCO3-
H+ is secreted into the lumen while K+ ions are imported in an antiport system. Cl- and bicarbonate ions are also transported in an antiport system. This maintains the normal physiological pH in the parietal cell and H+ is secreted into the lumen where it acts on the food particles.

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