|The gallbladder is located beneath the liver and drains bile into the duodenum via the biliary tree.|
|Latin||Vesica biliaris, vesica fellea|
|Gray's||subject #250 1197|
|Nerve||Celiac ganglia, vagus|
In vertebrates the gallbladder (cholecyst, gall bladder or biliary vesicle) is a small organ where bile is stored, before it is released into the small intestine. Humans can live without a gallbladder. The surgical removal of the gallbladder is called a cholecystectomy.
The gallbladder is a hollow organ that sits just beneath the right lobe of the liver.  In adults, the gallbladder measures approximately 8 centimetres (3.1 in) in length and 4 centimetres (1.6 in) in diameter when fully distended. The gallbladder has a capacity of about 100mL. :298
The gallbladder is shaped like a tapered sac, with the open end opening into the biliary tree and the cystic duct. Anatomically, the gallbladder is divided into three sections: the fundus, body, and neck: 
- The fundus is a rounded end that faces the front of the body. 
- The body (Latin: corpus) is in contact with the liver, lying in depression at the bottom of the liver. 
- The neck tapers and is continuous with the cystic duct, part of the biliary tree. The cystic duct unites with the common hepatic duct to become the common bile duct. At the neck of the gallbladder is a mucosal fold called Hartmann's pouch, where gallstones commonly get stuck. The angle of the gallbladder is located between the costal margin and the lateral margin of the rectus abdominis muscle. The fundus is at the same level as the transpyloric plane;
The gallbladder connects to the liver via the cystic duct gross anatomy and local ducts connecting to the liver, pancreas and duodenum of the small intestine.
Under the microscope, the layers of the gallbladder wall can be seen. The gallbladder wall's innermost surface is lined by a single layer of columnar cells. Underneath the epithelia is an underlying lamina propria, muscularis, perimuscular layer and serosa. Unlike elsewhere in the intestinal tract, the gallbladder does not have a muscularis mucosae, and the muscular fibres are not arranged in distinct layers. In greater detail, the layers are: 
- The epithelium is the innermost layer of the gallbladder, and is of simple columnar type. Underneath the epithelia is a lamina propria: together, these two layers are known as the mucosa.
- The submucosa is a thin layer of loose connective tissue with smaller blood vessels. It contains many elastin fibres, lymphatics, and in the neck of the gallbladder, glands which secrete mucous. The lymphatics of this layer help to drain water when the bile is concentrated, and the mucous glands may create a surface that protects the wall of the biliary tree.
- The muscularis, a layer of smooth muscular tissue. The interspersed muscle fibres lie in longitudinal, oblique and transverse directions, and are not arranged in separate layers. The muscle fibres here contract to expel bile from the gallbladder.
- The perimuscular ("around the muscle") fibrous tissue, another layer of connective tissue
- The serosa is a thick layer that covers the outer gallbladder, and is continuous with peritoneum, which lines the abdominal cavity. The serosa contains layer blood vessels and lymphatics.
Early in development, the human embryo has three layers and abuts an embryonic yolk sac. During the second week of embryological development, as the embryo grows, it begins to surround and envelop portions of this sac. The enveloped portions form the basis for the adult gastrointestinal tract. Sections of this gut begin to differentiate into the organs of the gastrointestinal tract, such as the oesophagus, stomach, and intestines. 
During the fourth week of embryological development, the stomach rotates. The stomach, originally lying in the midline of the embryo, rotates so that its body is on the left. This rotation also affects the part of the gastrointestinal tube immediately below the stomach, which will go on to become the duodenum. By the end of the fourth week, the developing duodenum begins to spout a small outpouching on its right side, which will go on to become the liver biliary tree. Just below this is a second outpouching, known as the cystic diverticulum, that will eventually develop into the gallbladder.
Anatomical variants of the gallbladder occur very rarely, although a range of abnormalities have been documented.
The number and structure of the gallbladder may vary. Occasionally two or even three gallbladders may coexist, either as separate bladders draining into the cystic duct, or sharing a common branch that drains into the cystic duct. Additionally, the gallbladder may fail to form at all. Gallbladders with two lobes separated by a septum may also exist. These abnormalities are not likely to affect function and are generally asymptomatic.
The location of the gallbladder with regard to the liver may also vary, with documented variants including gallbladders found within, above, on the left side of, behind, and detached from the liver. Such variants are very rare: from 1886 to 1998, only 110 cases of left-lying liver, or less than one per year, were reported in scientific literature.
The main purpose of the gallbladder is to store bile, or gall. The gallbladder is part of the biliary system and serves as a reservoir for bile, which is produced by the liver. The liver produces the bile and then it flows through the bile ducts into the gallbladder. The gallbladder releases the bile in response to a hormone called cholecystokinin, which is released from the small intestine. When the bile is released, it is released into the small intestine and its purpose is to break down large fat molecules into smaller ones. After the fat is absorbed, the bile is also absorbed and transported back to the liver for reuse.
When food containing fat (and amino acids) enters the digestive tract, it stimulates the secretion of cholecystokinin (CCK) from I cells of the duodenum and jejunum. In response to CCK, the adult human gallbladder, which stores about 50 millilitres (1.7 U.S. fl oz; 1.8 imp fl oz) of bile, contracts and releases its contents into the duodenum. The bile, originally produced in the liver, emulsifies fats in partly digested food.
During storage in the gallbladder, bile becomes more concentrated which increases its potency and intensifies its effect on fats.
"By far, the most common gallbladder problem is Gallstones" (Rodriguez). The gallbladder is supposed to store bile in a natural, semi-liquid form at all times. Hydrogen ions secreted from the inner lining of the gallbladder are supposed to keep the bile acidic enough to prevent hardening. To dilute the bile, water and electrolytes from the digestion system are added. Also, salts attach themselves to cholesterol molecules in the bile to keep them from crystallizing. Sometimes there can be too much cholesterol or bilirubin in the bile, or the gallbladder doesn't empty like it should and the systems listed above fail. This is how gallstones form. All it takes is a tiny bit of calcium to get coated with either cholesterol or bilirubin and crystallization of the bile, to form a gallstone. Gallstones are dangerous because they may never cause any pain or symptoms until they are causing a problem in the biliary system.
The recurrence rate of gallstone related issues is very high, so elective surgical resection of the gallbladder is the standard of care after such issues. This is fine because the digestive system will still be able to function properly . The gallbladder does not produce anything needed for digestion, it simply stores bile until digestion, when it is released into the small intestine. With no gallbladder, bile will just continuously drip from the liver during digestion for the breakdown of fats. Patients undergoing a cholecystectomy seldom have long-term post-surgical issues with the function of their digestive system .
A traditional cholecystectomy is most commonly performed from the infundibulum to the fundus.
Society and culture
Numerous words in the English language relate to the gallbladder and the bile that it stores. To have 'gall' is associated with bold behaviour, whereas to have 'bile' is associated with bitterness. 
In the Chinese language, the gallbladder (Chinese: 胆) is associated with courage and a plethora of related idioms, including using terms such as "a body completely [of] gall" (Chinese: 浑身是胆) to describe a brave person, and "single gallbladder hero" (Chinese: 孤胆英雄) to describe a lone hero. 
In other animals
Most vertebrates have gallbladders, whereas invertebrates do not. However, its precise form and the arrangement of the bile ducts may vary considerably. In many species, for example, there are several separate ducts running to the intestine, rather than a single common bile duct, as in humans. Several species of mammals (including horses, deer, rats, and various laminis) and several species of birds lack a gallbladder altogether, as do lampreys.
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|Wikimedia Commons has media related to Gall bladder.|
- Diagram of Human Stomach and Gallbladder – Human Anatomy Online dd, MyHealthScore.com.
- www.newchronicles.webs.com/f/gastrointestinalphysiology – Gastrointestinal Physiology Review.
- Anatomy photo:38:14-0100 at the SUNY Downstate Medical Center - "Stomach, Spleen and Liver: The Gallbladder and the Bile System"
- Rodriguez, D. (2010, Jan. 25). What Is the Gallbladder?. Everyday Health, Retrieved Mar. 20, 2011, from http://www.everydayhealth.com/gallbladder/what-is-the-...
- (2009, Jan.). Life Without a Gallbladder. Digestive Disorders, 30-31. Retrieved n.d., from Health Source - Consumer Edition (9780929661674).