Bile, produced by the hepatocytes, is secreted into channels called bile canaliculi, which run within each hepatic plate. These canaliculi travel toward the bile ducts, so that the bile and blood flow in opposite directions and do not mix. These do not have the platelike structure and are less functional, e.g., more ammonia into system and portal hypertension. 250-1500 ml of bile per day. Bile salts are cholesterol derivatives, principally cholic acid and chenodeoxycholic acid.
Bile salts form micelles, with the polar groups facing outward.
Lecithin, cholesterol, and other lipids in the small intestine enter the micelles to aid the digestion and absorption of fats. If it is in the bile and enters the intestine, the conjugated bilirubin can be modified by the intestinal flora to urobilinogen, which gives helps to give color to the feces. Some of the urobilinogen can also be reabsorbed and enter the general circulation. Unattached to albumin, the urobilinogen can be filtered and so gives urine a nice yellow. These changes make the molecules less active and more likely to be excreted.