Function of Bile in Fat Digestion and Absorption - Essay Example

Function of Bile in Fat Digestion and Absorption Bile is a yellowish brown digestive fluid produced solely by theliver. After secretion, the fluid flows to the gallbladder where it is stored until need arises. Unlike other secretions found along the gastrointestinal tract, bile juice hardly contains any enzymes. Instead, it contains electrolytes, water and organic molecules such as the bilirubin and bile acids. These components of the bile have two fundamental roles in the body i.e. excretion of several of waste products; and the digestion and absorption of fats.

Bile acids contained in bile are the key players in the digestion and absorption of fats. Their structure is modelled to facilitate the processes. They have a cholesterol derived section joined to an amino acid conjugate. Furthermore, the bile acids are naturally facial amphipathic. They contain a hydrophobic and a hydrophilic portion. The amino acid conjugate is both polar and hydrophilic. However, the cholesterol derived section has one face with a methyl group being hydrophobic and the other face containing hydroxyl groups being hydrophilic.

The nature of bile acids enables them to emulsify lipid aggregates in a detergent like action. The fats, which are hydrophobic, tend to join together with other fat droplets to form large molecules. However, the bile hinders this from happening. In the ileum, the hydrophobic section of the bile is absorbed in the fat droplet leaving a tail like hydrophilic end which repels other fat molecules. The emulsification increases the surface area of the fats hence increasing the rate of digestion by enzymatic lipases.

The bile acids further solubilize the lipids by forming micelles and aid in their transport through aqueous environments. The micelles are acted up on by lipases and broken down into fatty acids and mono glycerides. These broken down units are small enough to penetrate through the walls of the small intestine through the process of absorption. They then enter the epithelial cells of the intestinal walls where the mono glycerides and fatty acids are converted into triglycerides with a protein coating.

The newly formed water soluble chylomicrons enter into the lymphatic system and are transported through the bloodstream to various organs of the body for usage. In conclusion, almost 90 percent of used bile salts are recycled via enterohepatic circulation. The cycle is repeated about fifteen times before the bile salts are discarded in the feces. Nevertheless, there is constant secretion of bile salts in small amounts by the liver to replace those salts that are not recycled.