What Is Bile?

Bile helps people digest what they eat.

Digestion is an incredibly complex process by which the human body breaks down the food that a person eats into smaller parts that the body can use for processes like cellular respiration. The stomach's role is huge in this process, but of nearly equal importance is the role of the liver and bile. An investigation of the components of bile and how these components work with food reveals why bile is so crucial to digestion.

Definition

Bile is a liquid produced by the liver and stored in the gallbladder. It is a digestive substance that ranges in color from greenish yellow to brown, depending on how concentrated it is and the exact percentage of each component within it.

Components

According to Colorado State University and Gallbladder Attack, water, phospholipids, bile acids, bile salts and bile pigments all make up bile. Bile also contains electrolytes, bilirubin and cholesterol.

Functions

Gallbladder Attack and Colorado State University explain that bile has two main functions. First, on the most basic level, bile acts like a surfactant that sorts good and bad substances in the body; it helps the body get rid of waste like bilirubin and cholesterol. In many ways, its role is similar to the kidney's. In order to do this, however, bile breaks down the substances in food, which is why it is discussed in terms of the digestive process. The acids in bile absorb fats and vitamins that dissolve in fat into the small intestine. Without fats and vitamins, none of the cells in the human body would be able to function.

Production and Flow

Cells in the liver called hypatocytes produce bile initially. This "first stage" bile drains through bile ducts. As this happens, epithelial cells dilute the bile with a watery solution. The bile then enters the common hepatic duct (sphincter of Oddi), travels into the pancreatic duct and finally empties into the duodenum (the first part of the small intestine).

Sometimes the sphincter of Oddi remains closed during bile production. This may happen if a person hasn't eaten for a while and doesn't need the bile to help break down food. In this case, the bile travels to the gallbladder, which stores it for later. While the bile is in the gallbladder, the bile becomes highly concentrated because the body absorbs water and electrolytes from it. The body also releases cholesterol into the bile. The bile dissolves this cholesterol so the body can get rid of it. When a person eats again, the duodenum releases cholecystokinin, which stimulates the gall bladder to release the concentrated bile.

Common Problems

Common problems associated with bile production include bile reflux (similar to acid reflux) and gall stones. Poor bile production may result in deficient digestion, leading to nutrient deficiencies.

References

• Colorado State University: Secretion of Bile and the Role of Bile Acids in Digestion
• Gallbladder Attack: About the Gallbladder
• Nation Master: Bile Duct