Basic structure and function of the gallbladder

This article will briefly explain where your gallbladder is and how it functions. This will give you a greater understanding of why gallbladder problems occur in the first place, thereby helping you maintain and restore your gallbladder health.

The gallbladder – A Squirt Gun in Your Gut

The gallbladder is a small, sac-like organ that is approximately 8 cms (3 inches) long and 4 cms (1.5 inches) wide. It sits behind the liver, in the upper right segment of your abdomen, roughly at the level of your lowest right rib.
The walls of the gallbladder are composed of smooth muscle. This allows the gallbladder to contract forcefully in order to squirt bile into the common bile duct, and then into your small intestine, during a meal. Your gallbladder really behaves like a squirt gun.

Your gallbladder has two main functions: to store bile and to concentrate bile, so that it becomes more potent by the time it is needed. Generally bile is concentrated five-fold while stored in the gallbladder. The gallbladder is merely a sac for storing and ejecting bile – so it cannot take the blame for gallstone formation or inflammation.

It is the health of your liver that is the biggest determinant in whether or not you will develop gallbladder disease, as the liver determines the quality of bile produced and whether or not that bile leads to stone formation.

What is the Function of Bile?

Bile is a brownish green or yellow liquid that has three important functions in the body:

1. Bile contains bile acids which act as an emulsifier or detergent, critical for the digestion and absorption of fats and fat soluble vitamins in the small intestine. Bile basically breaks fat molecules into smaller globules, so that digestive enzymes (lipases) can act to break them down, making them ready for absorption. Bile acids are also known as bile salts.
2. Bile is an excretion route for many wastes and toxins that need elimination from the body. These wastes enter the small intestine in the bile and are then eliminated in the faeces. Bilirubin is the breakdown product of red blood cells and it forms a major component of bile. Your body excretes excess fat and fat soluble toxins as well as hormone residues through bile.
3. Bile deodorises the stool, gives it its brown color and has a gentle laxative effect. People with overly odorous faeces often do not secrete sufficient bile. Likewise, constipated people often do not produce enough bile. In fact, in many instances, a sluggish bowel is due to a sluggish liver that is not producing sufficient good quality bile.

Where Does Bile Come From?

The average person’s liver produces between  400 and 800 ml (13½ and 27 ounces) of bile each day.

Liver cells (hepatocytes) produce bile and secrete it into tiny tubes within the liver called canaliculi. From there, the bile travels into bile ducts within the liver. At this stage bile contains large quantities of bile acids and cholesterol.

As bile travels through the bile ducts of the liver, it is modified by the addition of a bicarbonate rich watery solution, secreted by the liver cells that line the bile ducts. Bile then travels into the gallbladder where it is stored and concentrated, ready to be secreted into the intestines during a meal.

When the bile is being concentrated in the gallbladder, 90 percent of the water in it gets reabsorbed. That leaves only approximately a few tablespoons of concentrated bile, ready to be ejected when needed. The amount of bile your gallbladder ejects during a meal depends on several factors, including how thick the bile is (thick bile doesn’t squirt out as easily) and how efficiently the walls of your gallbladder are able to contract.

The role of bile in healthy digestion

Knowing how the gallbladder functions will assist in understanding which foods are beneficial for gallbladder health and which foods you would be wise to avoid. If you’ve had a long-standing gallbladder problem you’ll learn how to minimize the risk of a full blown gallbladder attack.

Bile is an alkaline fluid with a pH between 7.6 and 8.6. Bile acids are a major component of bile and they are actually made from cholesterol.

Cholesterol is a very valuable substance that has numerous beneficial effects in your body; this is merely one of them. You need cholesterol in order to have efficient fat digestion. Most of the cholesterol in your body was made in your liver. In the production of bile, cholesterol is converted into the bile acids cholic and chenodeoxycholic acids, which are then bound to the amino acids glycine or taurine.

After this occurs, the bile acids are said to be conjugated and ready to be used. Glycine and taurine are therefore very important for the production of healthy bile in individuals with gallstones or excessively thick and sludgy bile.

Bile production is actually the major way your body gets rid of excess cholesterol it no longer requires. Your liver converts an average of 500 milligrams of cholesterol into bile acids each day. The bile eventually enters your intestines and some of it is eliminated from your body in bowel actions. However, if you are constipated you will not be excreting cholesterol efficiently. Too much of the cholesterol can be reabsorbed back into your bloodstream and then end up back at your liver.
This is why having regular and efficient bowel habits is an important strategy in maintaining a healthy cholesterol level.

Bile secretion in fat digestion

Bile is required for fat digestion, therefore if you have not eaten for some time, bile tends to stay in your gallbladder where it is concentrated. A small amount of bile will trickle out of your gallbladder, along the common bile duct on its way to your small intestine. Before emptying into your small intestine, the bile duct passes through your pancreas. This is important to remember because it is possible for a gallstone to become trapped in the duct within the pancreas, causing an acute case of pancreatitis. This is a medical emergency and requires immediate hospital treatment.

To prevent bile from continually trickling into your small intestine, a valve at the end of the common bile duct remains closed between meals, preventing bile from entering the small intestine. This valve is called the Sphincter of Oddi or the hepatopancreatic sphincter and it prevents both bile and pancreatic digestive enzymes from entering the small intestine between meals when they are not required.

This diagram shows the location of the gallbladder and how bile travels through the bile ducts.

When food that contains some fat enters the first part of your small intestine (duodenum), just below your stomach, cells lining your small intestine secrete a hormone called CCK into your bloodstream. The full name of this hormone is cholecystokinin but it’s commonly abbreviated to CCK. The word is derived from Greek – “whole” refers to bile, “cyst” refers to sac and “kinin” means move. So the word means “move the bile sac”.

This hormone triggers your gallbladder to contract and it makes the sphincter of Oddi open up, allowing bile to enter the small intestine. CCK also triggers the pancreas to release its digestive enzymes into your small intestine.

When bile enters your small intestine, it acts like a detergent, helping to break the fat globules into smaller molecules, so that they can be completely digested by enzymes. Fat digesting enzymes are called lipases. Most of the fats that get digested in your small intestine do not get absorbed into your bloodstream like other nutrients, vitamins and minerals you have consumed. Most fats get absorbed directly into your lymphatic system, and from there get carried in lymphatic vessels to your heart. This makes sense because fat is a rich energy source and is actually the preferred energy source for your hard working heart muscle.

Long chain fatty acids that you consume in your diet must first be emulsified by bile, then digested by lipases and then absorbed into your lymphatic system. However, short chain fatty acids, and some medium chain fatty acids do not require bile for their digestion. They get absorbed directly into the bloodstream and are taken straight to the liver. Coconut oil is mostly made up of the medium chain fatty acid lauric acid. It does not require bile for digestion, and therefore does not place a strain on the gallbladder in individuals with compromised gallbladder function.