Nepedia
Back to Discover
Advanced Reader
🧬

Gallbladder

life science Maturity 9-11 Next article →

The gallbladder, also known as the cholecyst, is a small and vital organ in vertebrates.

Gallbladder and common bile duct ultrasound
Gallbladder and common bile duct ultrasound

It is a hollow, pear-shaped organ that stores and concentrates bile. Bile is a liquid produced by the liver that is essential for the digestion of fats. By holding this liquid, the gallbladder ensures that the body has a concentrated supply ready when needed. This process helps the small intestine break down fats effectively during digestion.

The mechanism of the gallbladder involves several precise steps. First, the liver produces bile and sends it through the common hepatic duct. This bile enters the gallbladder to be stored. While inside, the gallbladder concentrates the bile by 3 to 10 times. It achieves this by actively transporting sodium and chloride ions across its epithelium. This movement creates osmotic pressure, which pulls water and other electrolytes out of the bile.

Gallbladder - intermed mag
Gallbladder - intermed mag

When fat enters the digestive tract, the duodenum and jejunum release a hormone called cholecystokinin (CCK). In response to CCK, the smooth muscle in the gallbladder wall contracts. This rhythmic contraction expels the concentrated bile through the cystic duct and into the common bile duct. The bile then enters the duodenum to emulsify fats.

The human gallbladder has a specific structure divided into three distinct sections. The fundus is the rounded base that faces the abdominal wall. The body is the middle section that sits in a depression on the liver. Finally, the neck tapers and connects to the cystic duct.

Gallbladder and common bile duct ultrasound
Gallbladder and common bile duct ultrasound

At the junction of the neck and the cystic duct, a fold called Hartmann's pouch may form. The internal wall is lined with columnar cells that have tiny hair-like structures called microvilli. These cells help with the absorption of fluids. The wall also contains deep outpouchings called Rokitansky–Aschoff sinuses, which can extend through the muscular layer.

Understanding how the gallbladder develops helps explain its place in the body. It begins as an endodermal outpouching of the embryonic gut tube. During the second week of embryogenesis, the embryo begins to envelop portions of the yolk sac. This forms the basis of the gastrointestinal tract. By the fourth week, the stomach rotates to the left. This rotation affects the duodenum, which is the part of the tube below the stomach. During this time, a second outpouching called the cystic diverticulum sprouts on the right side. This small bump eventually develops into the adult gallbladder.

While the gallbladder is usually standard, there is significant anatomical variation. In adults, the organ typically has a capacity of about 30 milliliters. However, some people may be born with two or even three gallbladders. Others might have a gallbladder with two lobes separated by a septum. Some individuals even have a Phrygian cap, which is a harmless fold in the fundus. Very rare cases involve the gallbladder being located above, behind, or even detached from the liver. Most of these variations are asymptomatic and do not affect how the body functions.

Health issues often arise when the bile becomes saturated with certain materials.

Gallbladder stones
Gallbladder stones

This can lead to the formation of gallstones, which are typically made of cholesterol or bilirubin. Bilirubin is a product created when the body breaks down hemoglobin. If these stones block a duct, they can cause severe, colicky pain in the upper-right abdomen. This blockage can also cause cholecystitis, which is inflammation of the gallbladder. This inflammation may be caused by stones, infection, or autoimmune disease. If the stone blocks the pancreatic duct, it can lead to pancreatitis.

When medical intervention is required, doctors may perform a cholecystectomy. This is a surgical procedure to remove the gallbladder. It can be done through an open surgery or a laparoscopic approach. While the gallbladder is gone, the liver simply sends bile directly into the biliary tree. Some patients may experience indigestion or postcholecystectomy syndrome after the procedure. Although rare, other complications can include biliary injury or a biloma, which is an accumulation of bile in the abdominal cavity.

Ultrasonography of sludge and gallstones, annotated
Ultrasonography of sludge and gallstones, annotated

Scientists also study the link between gallbladder removal and cancer risks, such as right-sided colon cancer.

676 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (4)
File:Gallbladder - intermed mag.jpg
Gallbladder - intermed mag.jpg
File:Gallbladder and common bile duct ultrasound.jpg
Gallbladder and common bile duct ultrasound.jpg
File:Gallbladder stones.jpg
Gallbladder stones.jpg
File:Ultrasonography of sludge and gallstones, annotated.jpg
Ultrasonography of sludge and gallstones,...
More to explore

✨ What else?

Related topics you might enjoy

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.