Basic Gallbladder Anatomy and Gallstones
People seldom talk about their gallbladder, except of course if it is causing them pain. There are several diseases that can plague a gallbladder, many of which can lead to a gallbladder removal surgery.
Experts believe that after a gallbladder removal surgery one can still live a normal happy life. Do we really need to a gallbladder? What exactly does it do for us?
Let us find out what the gallbladder is before we dig deeper for answers to these questions.
What is a Gallbladder?
The human gallbladder is a muscular sac that stores bile. It sits under the liver in the upper right side of the abdomen.
The liver produces about a liter of bile each day and stores it in the gallbladder. Bile is a green sticky alkaline liquid which among other things plays an important role in the digestion of fat.
Basic Gallbladder Anatomy
The gallbladder is about 7 to10 centimeters long and can hold up to about 50 milliliters of bile.
A full gallbladder is pear-shaped. An empty gallbladder looks flat and deflated.
The narrow part of a gallbladder gives rise to the cystic duct. The cystic duct joins the common hepatic duct to form the common bile duct which leads to the small intestine (duodenum).
A healthy gallbladder should be free of bile stones and be able to contract and send bile into the digestive tract.
Here is what happens when you eat a fatty food
After eating a big slice of pizza, your gallbladder plays a key role in the digestion of fat.
Fat leaves the stomach as large molecules (macromolecules) and needs to be broken down into smaller molecules before ‘real’ fat digestion can begin.
When chyme (partly digested food) from the stomach reaches the first part of the small intestine (duodenum), it signals cells of the gut to secrete a digestive hormone called Cholecystokinin (CCK) into the blood stream.
CCK triggers the contraction of the gallbladder. The gallbladder then contracts to push bile through its bile duct into the duodenum. Bile mixes with chyme in the lumen of the small intestine.
The Role of Bile in Fat Digestion
Before we get into the role of bile in fat digestion, it is important to take a closer look at the structure of a fat molecule.
“Triglycerides” is the fancy name for fat in the foods we eat. A triglyceride molecule has a glycerol backbone holding 3 fatty acid molecules.
As you may already know, fat and water don’t mix (fats are hydrophobic). You can observe this by pouring a bit of cooking oil inside a glass of water. You should see oil droplets sticking together to form blobs.
In the small intestine, bile salts break down lumps of fat into smaller bits in a process called emulsification – often described as detergent action. The action of bile salts is similar to what soap does when you are washing a plate full of grease. The soapy water cuts through the grease and allows you to obtain a clean plate.
Note that bile does not do any real digestion. It simply emulsifies fat, physically breaking large aggregates into tiny droplets of triglycerides, to increase the surface area for efficient enzyme action.
Enzyme digestion by pancreatic lipase breaks down triglyceride molecules into pools of dissolved monoglycerides and fatty acids – these can effectively diffuse into the intestinal absorptive cells, absorbed and transported into the blood.
Bile is also a key player in the digestion of other types of lipids such as cholesterol.
What are Gallstones?
Gallstones are coagulated bile. They start as little crystals in the gallbladder. Over the years, these crystals can grow in the pool of bile to form stones.
There are two types of gallstones; Cholesterol stones which are yellow-green in color and Pigment stones which are black in color.
Some gallstones are as tiny as a grain of sand and others are as large as a golf ball.
How do you get gallstones?
To better understand how gallstones develop, it is important to know that bile is made by liver cells from various substances including cholesterol and a pigment called bilirubin.
Bilirubin (from dead red blood cells) and excess cholesterol which the body doesn’t need are processed in the liver and made into bile. Bile produced in the liver is sent to the gallbladder for storage.
Stones may start to grow when one or more components of bile become imbalanced. The type of stone depends on the type of imbalance. Too much cholesterol and not enough bile salts to dissolve it can lead to cholesterol stones.
While very little is known about the formation of pigment stones, scientists believe they contain calcium salts, bilirubin, cholesterol and other substances responsible for binding the stone.
Gallstones have risk factors just like many other illnesses. Some important factors of cholesterol stones are obesity, diabetes, and hyperlipidemia. In general, anything that raises cholesterol levels is an important factor of cholesterol stones.
Pigment stones are caused by the abnormal destruction of red blood cells (haemolysis). People with sickle cell disease are more susceptible to pigmented stones. Even though cholesterol stones are more common, people with diseases associated with haemolysis are more likely to get pigment stones.
Some Complications of Gallstones
If you’ve suffered a gallstone attack then you’ll probably agree that the one word most suitable to describe it is ‘pain’.
Stones in the gallbladder can roll into the bile duct and obstruct it. When the gallbladder tries to pump bile against this obstruction, the result is severe pain (biliary colic) in the right or even the central part of the upper abdomen. The pain can radiate to the back and the right shoulder blade.
The pain usually persists until the stone rolls back into the gallbladder. This may take several minutes to several hours. A typical gallbladder pain comes and goes as stones roll in and out of the bile duct.
Gallstones can disrupt the normal flow of bile preventing it from reaching the intestines in sufficient amounts.
Besides its key role in fat digestion, bile also neutralizes the acidity of chyme from the stomach. The acidity comes from hydrochloric acid in the stomach which kills microbes and helps digest food.
The stomach has a mucus layer that protects it from the acidic content of the digestive system. The intestines on the other hand have no such protective layer. Bile (a very alkaline substance) neutralizes the acidity of chyme at the start of the small intestine.
Therefore, an obstruction to the normal flow of bile may cause problems such as acid burns; which can occur when the acidic content from the stomach isn't completely neutralized.
Do you think a person can live a normal happy life after a gallbladder removal surgery?
Surgery is one of the most common remedies to alleviate pain caused by gallstones. Depending on the situation, surgeons may perform a keyhole surgery, also known by its fancy name Laparoscopic surgery. This type of surgery is done to remove the gallbladder and stones through a tiny incision. Sometimes a more invasive surgery is required.
As you may have already gathered, the gallbladder plays an important role in the digestive system. Wouldn’t it be better to remove the gallstone leaving the gallbladder intact? There are gallstone treatments that target and dissolve existing gallstones. These treatments only address existing stones and won’t prevent new ones from developing in the future – a downside.
However there are ways to reduce your risk of developing gallstones.