Question

How does bile help in the digestion of fats?

Answer 1

Hint: Bile acids are derivatives of hepatocyte-synthesized cholesterol. Many compounds, including salts (also known as bile acids), water, copper, cholesterol, and pigments, make up bile. In fat digestion, one of these pigments that is responsible for jaundice is also as it accumulates in the blood and body tissues.

Complete answer:
The digestive juice which is secreted by the liver is bile. While no digestive enzymes are present in it, it plays an important role in the digestion of fats. There are bile pigments such as bilirubin and biliverdin in bile juice. In order for the pancreatic enzymes to quickly work on them, these pigments break down large fat globules into smaller globules. The technique is known as fat emulsification. As a result of the presence of $NaHC{O}_3$, bile juice also makes the medium alkaline and stimulates lipase as well.
Bile acids, that is, contain both hydrophobic (lipid-soluble) and polar (hydrophilic) faces, are amphipathic. Their amphipathic nature allows two major functions to be performed by bile acids:
- Emulsification: Bile acids possess detergent action on dietary fat particles that allows fat globules to break down or be emulsified in minute droplets. Emulsification is not digestion, but is essential because it significantly increases the area of the fat surface, making it accessible for digestion by lipases that are unable to reach the lipid droplets within.
- Solubilization and transport of lipids in an aqueous environment: bile acids are lipid carriers and, through the formation of micelles, are capable of solubilizing certain lipids-lipid aggregates such as fatty acids, cholesterol, and monoglycerides-which remain suspended in water. Bile acids are also essential for fat-soluble vitamins to be transferred and consumed.

Note: Bile is a complex fluid that passes from the biliary tract into the small intestine, comprising water, electrolytes, and a battery of organic molecules, including bile acids, cholesterol, phospholipids, and bilirubin. In all animals, there are two profoundly significant functions of bile:
- Bile contains bile acids, which are essential for digestion and absorption in the small intestine of fats and fat-soluble vitamins.
- Several waste products, including bilirubin, are extracted from the body by bile secretion and faecal removal.