Bile, also known as gall, is a thick and sticky, yellow-green fluid made by the liver. Bile breaks down fats into fatty acids so that they can be absorbed into your body through your digestive tract. Bile's other important functions include getting rid of certain waste products from your body, such as hemoglobin —a protein that comes from destroyed red blood cells and excess cholesterol.
This article discusses the various functions of bile in your body—how it's made, what it does, and why your body needs it. Further down, you will also find information about bile-related medical conditions, some of which can be life-threatening. A digestive fluid produced by the liver and stored in the gallbladder that breaks down fats in the small intestine and helps remove wastes from the body.
Many compounds make up bile, but one of the most important ones are bile acids—also known as bile salts, which blend fats together during digestion so that your body can absorb them. Bile is made of the following components:. Bilirubin is a waste product of hemoglobin that carries oxygen in the blood. Bilirubin is secreted into bile so that it can pass through the digestive system then leave the body in feces.
Bile plays a key role in digesting fats so that they can be used by the body. Bile is also necessary for removing what the body cannot use. Bile serves three main functions:. By breaking down fats, bile acids also help your intestines absorb the fat-soluble vitamins A, D, E, and K.
The liver filters, breaks down, converts, and stores various substances so that your body can use or remove them. The liver also produces about to 1, milliliters 27 to 34 fluid ounces of bile each day. Bile is secreted by the liver and stored in the gallbladder, a small organ attached to the underside of the liver. During meals, bile is released from the gallbladder through a tube called the common bile duct. This duct connects your gallbladder and liver to your duodenum , the first part of your small intestine.
Humans have wondered about bile for ages, but it wasn't until that theories about bile were first documented. Fast forward to the s when scientists began to study the chemistry and biology of bile in detail. In , a German scientist named Heinrich Weiland won a Nobel Prize in chemistry for revealing the composition of bile acids.
His discovery helped clarify the important functions of bile acids in the body. Discoveries related to bile are ongoing.
Research published in in the journal Nature documented the finding that novel bile acids are made by microbes in the gut. More research is needed to confirm the findings, but the study suggests that the gut microbiome—bacteria and other microbes that live in your gastrointestinal tract—may play a role in producing both bile acids and enzymes in the liver. Between meals, bile is stored in the gallbladder and only a small amount of bile flows into the intestine. Bile also becomes more concentrated during this storage process.
Fatty foods that enters the duodenum prompt hormonal and nerve signals that cause the gallbladder to contract. The hormones that control this process are:. Signals also come from the vagus nerve , which extends from the brainstem all the way down to your abdomen. As a result, bile flows into the duodenum and mixes with food, stomach acids, and digestive fluids from the pancreas , which helps the intestines absorb nutrients into the bloodstream. Most of the bile acids are absorbed through the lower intestine then circulated into the bloodstream and back to the liver.
Bile is a liquid produced by your liver and stored in your gallbladder. When prompted by hormones and the vagus nerve, bile is released from your gallbladder into your duodenum and intestines. Your body then uses it to break down fats, absorb vitamins, and remove wastes that your body doesn't need.
Many people are familiar with jaundice , when bilirubin the main pigment in bile accumulates in the bloodstream. It is common in newborns, who are not always developed enough to remove the pigment from their system.
Classic signs include dark urine and yellowing of the skin and eyes. But jaundice can also occur in people of all ages when bile flow from the liver to the duodenum slows or stops for another reason.
Known as cholestasis , this can occur as a result of liver, pancreas, or gallbladder disorders, or any damage to bile ducts. Bile is produced by hepatocytes cells in the liver and passes through the bile ducts to the cystic duct. From the cystic duct, bile is pushed into the gallbladder by peristalsis muscle contractions that occur in orderly waves. Bile is then slowly concentrated by absorption of water through the walls of the gallbladder.
The gallbladder stores this concentrated bile until it is needed to digest the next meal. Foods rich in proteins or fats are more difficult for the body to digest when compared to carbohydrate-rich foods see Macronutrients. The walls of the duodenum contain sensory receptors that monitor the chemical makeup of chyme partially digested food that passes through the pyloric sphincter into the duodenum.
When these cells detect proteins or fats, they respond by producing the hormone cholecystokinin CCK. CCK enters the bloodstream and travels to the gallbladder where it stimulates the smooth muscle tissue in the walls of the gallbladder. When CCK reaches the gallbladder, it triggers the smooth muscle tissue in the muscularis layer of the gallbladder to contract.
The contraction of smooth muscle forces bile out of the gallbladder and into the cystic duct. From the cystic duct, bile enters the common bile duct and flows into the ampulla of Vater , where the bile ducts merge with the pancreatic duct. Bile then flows from the ampulla of Vater into the duodenum where it breaks the fats into smaller masses for easier digestion by the enzyme pancreatic lipase. Gallstones are hard masses of bile salts, pigments, and cholesterol that develop within the gallbladder.
These solid masses form when the components of bile crystallize. The rest of the bile is diverted through the cystic duct into the gallbladder to be stored. When food enters the small intestine, a series of hormonal and nerve signals triggers the gallbladder to contract and the sphincter of Oddi to relax and open. Bile then flows from the gallbladder into the small intestine to mix with food contents and perform its digestive functions.
The liver extracts these bile salts from the blood and resecretes them back into the bile. Bile salts go through this cycle about 10 to 12 times a day.
Each time, small amounts of bile salts escape absorption and reach the large intestine, where they are broken down by bacteria. Some bile salts are reabsorbed in the large intestine. The rest are excreted in the stool. The gallbladder , although useful, is not necessary.
If the gallbladder is removed for example, in a person with cholecystitis Cholecystitis Cholecystitis is inflammation of the gallbladder, usually resulting from a gallstone blocking the cystic duct. Typically, people have abdominal pain, fever, and nausea.
Ultrasonography can usually Gallstones Gallstones Gallstones are collections of solid material predominantly crystals of cholesterol in the gallbladder. The liver can secrete too much cholesterol, which is carried with bile to the gallbladder Gallstones may form in the gallbladder or bile ducts.
Gallstones usually cause no symptoms. However, gallstones may block the flow of bile from the gallbladder, causing pain biliary colic or inflammation.
They may also migrate from the gallbladder to the bile duct, where they can block the normal flow of bile to the intestine, causing jaundice Jaundice in Adults In jaundice, the skin and whites of the eyes look yellow. Jaundice occurs when there is too much bilirubin a yellow pigment in the blood—a condition called hyperbilirubinemia.
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