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Gallbladder

 
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The gallbladder (or cholecyst, sometimes gall bladder) is a small non-vital organ
Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
 which aids in the digestive process and concentrates bile
Bile

Bile or gall is a bitter yellow or green fluid secreted by hepatocytes from the liver of most vertebrates. In many species, bile is stored in the gallbladder between meals and upon eating is discharged into the duodenum where the bile aids the process of digestion of lipids....
 produced in the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
.

Human anatomy
The cystic duct
Cystic duct

The cystic duct is the short duct that joins the gall bladder to the common bile duct. It usually lies next to the cystic artery. It is of variable length....
 connects the gall bladder to the common hepatic duct
Common hepatic duct

The common hepatic duct is the duct formed by the convergence of the right hepatic duct and the left hepatic duct . The common hepatic duct then joins the cystic duct coming from the gallbladder to form the common bile duct....
 to form the common bile duct
Common bile duct

Bile, which is synthesized in the liver, is carried via the right and left hepatic ducts, with both converging to form the common hepatic duct. The cystic duct opens at the lower end of the common hepatic duct forming the common bile duct....
. This common bile duct then joins the pancreatic duct
Pancreatic duct

The pancreatic duct, or duct of Wirsung, is a duct joining the pancreas to the common bile duct to supply pancreatic juices which aid in digestion provided by the "exocrine pancreas"....
, and enters through the hepatopancreatic ampulla at the major duodenal papilla
Major duodenal papilla

The common bile duct and the pancreatic duct together perforate the medial side of the second portion of the duodenum obliquely, some 7 to 10 cm below the pylorus, forming a structure called the major duodenal papilla....
.

The fundus of the gallbladder is the part farthest from the duct, located by the lower border of the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
.






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Encyclopedia


The gallbladder (or cholecyst, sometimes gall bladder) is a small non-vital organ
Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
 which aids in the digestive process and concentrates bile
Bile

Bile or gall is a bitter yellow or green fluid secreted by hepatocytes from the liver of most vertebrates. In many species, bile is stored in the gallbladder between meals and upon eating is discharged into the duodenum where the bile aids the process of digestion of lipids....
 produced in the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
.

Human anatomy


The cystic duct
Cystic duct

The cystic duct is the short duct that joins the gall bladder to the common bile duct. It usually lies next to the cystic artery. It is of variable length....
 connects the gall bladder to the common hepatic duct
Common hepatic duct

The common hepatic duct is the duct formed by the convergence of the right hepatic duct and the left hepatic duct . The common hepatic duct then joins the cystic duct coming from the gallbladder to form the common bile duct....
 to form the common bile duct
Common bile duct

Bile, which is synthesized in the liver, is carried via the right and left hepatic ducts, with both converging to form the common hepatic duct. The cystic duct opens at the lower end of the common hepatic duct forming the common bile duct....
. This common bile duct then joins the pancreatic duct
Pancreatic duct

The pancreatic duct, or duct of Wirsung, is a duct joining the pancreas to the common bile duct to supply pancreatic juices which aid in digestion provided by the "exocrine pancreas"....
, and enters through the hepatopancreatic ampulla at the major duodenal papilla
Major duodenal papilla

The common bile duct and the pancreatic duct together perforate the medial side of the second portion of the duodenum obliquely, some 7 to 10 cm below the pylorus, forming a structure called the major duodenal papilla....
.

The fundus of the gallbladder is the part farthest from the duct, located by the lower border of the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
. It is at the same level as the transpyloric plane
Transpyloric plane

An upper transverse line, the transpyloric is located halfway between the jugular notch and the upper border of the symphysis pubis; this indicates the margin of the transpyloric plane, which in most cases cuts through the pylorus, the tips of the ninth costal cartilages and the lower border of the first lumbar vertebra....
.

Microscopic anatomy

The different layers of the gallbladder are as follows:
  • The gallbladder has a simple columnar
    Simple columnar epithelium

    A simple columnar epithelium is a columnar epithelium that is uni-layered. In humans, a simple columnar epithelium forms a lining in the uterus and in most organs of the digestive tract including the stomach, small intestine, and large intestine....
     epithelial
    Epithelium

    In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
     lining characterized by recesses called Aschoff's recesses, which are pouches inside the lining.
  • Under the epithelium
    Epithelium

    In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
     there is a layer of connective tissue
    Connective tissue

    Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
     (lamina propria).
  • Beneath the connective tissue
    Connective tissue

    Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
     is a wall of smooth muscle
    Smooth muscle

    Smooth muscle is a type of non-striated muscle, found within the tunica media layer of large and small arteries and veins, the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye....
     (muscularis externa) that contracts in response to cholecystokinin
    Cholecystokinin

    Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is synthesised by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and ca...
    , a peptide
    Peptide

    Peptides are short polymers formed from the linking, in a defined order, of a-amino acids. The link between one amino acid residue and the next is known as an amide chemical bond or a peptide bond....
     hormone
    Hormone

    Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
     secreted by the duodenum
    Duodenum

    The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
    .
  • There is essentially no submucosa
    Submucosa

    In the gastrointestinal tract, the submucosa is the layer of dense irregular connective tissue that supports the mucosa, as well as joins the mucosa to the bulk of underlying smooth muscle ....
     separating the connective tissue from serosa and adventitia
    Adventitia

    Adventitia is the outermost connective tissue covering of any Organ , Blood vessel, or other structure. It is also called the tunica adventitia....
    , but there is a thin lining of muscular tissue to prevent infection.


Section References

Function

The gallbladder stores about 50 mL (1.7 US fluid ounce
Fluid ounce

A fluid ounce is a unit of volume in both the Imperial unit and the United States customary units systems. It is common to refer to the unit simply as an ounce, especially in cases where no confusion with the unit of mass is likely to occur....
s / 1.8 Imperial fluid ounces) of bile
Bile

Bile or gall is a bitter yellow or green fluid secreted by hepatocytes from the liver of most vertebrates. In many species, bile is stored in the gallbladder between meals and upon eating is discharged into the duodenum where the bile aids the process of digestion of lipids....
, which is released when food
Food

Food is any substance, usually composed of carbohydrates, fats, proteins and water, that can be Eating or Drinking by an animal or human for nutrition or pleasure....
 containing fat enters the digestive tract
Gastrointestinal tract

The digestive tract is the system of Organ s within multicellular animals that takes in food, digestion it to extract energy and nutrients, and expels the remaining waste....
, stimulating the secretion
Secretion

Secretion is the process of, elaborating and releasing Chemical compound from a cell , or a secreted chemical substance or amount of substance. In contrast to excretion, the substance may have a certain function, rather than being a waste product....
 of cholecystokinin
Cholecystokinin

Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is synthesised by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and ca...
 (CCK). The bile
Bile

Bile or gall is a bitter yellow or green fluid secreted by hepatocytes from the liver of most vertebrates. In many species, bile is stored in the gallbladder between meals and upon eating is discharged into the duodenum where the bile aids the process of digestion of lipids....
, produced in the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
, emulsifies fats and neutralizes acids in partly digested food.

After being stored in the gallbladder the bile
Bile

Bile or gall is a bitter yellow or green fluid secreted by hepatocytes from the liver of most vertebrates. In many species, bile is stored in the gallbladder between meals and upon eating is discharged into the duodenum where the bile aids the process of digestion of lipids....
 becomes more concentrated than when it left the liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
, increasing its potency and intensifying its effect on fats. Most digestion occurs in the duodenum
Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
.

Vertebrates have gallbladders (except the horse and the rat) while invertebrates do not. This is because vertebrates eat in boluses
Bolus (digestion)

In digestion, a bolus is a mass of food that has been Mastication and swallowed. Once a bolus reaches the stomach, digestion begins.* Compare to chyme....
 while invertebrates are constantly eating. To digest a large bolus of food requires a large amount of digestive secretions, hence the presence of a gallbladder.

The human gallbaldder is shaped like a grape, although the organ's shape and function vary considerably among other mammalian species; in fact, in some species, such as the lamoid
Lamoid

Lamoid is a group of South American camelids, which includes the guanaco, vicuna, alpaca and llama. The digestive system of lamoids is distinctive, with a noteworthy capability for digesting certain toxins....
s, the gallbladder is absent.

See also

  • Cholecystectomy
    Cholecystectomy

    Cholecystectomy is the surgical removal of the gallbladder. Despite the development of non-surgical techniques, it is the most common method for treating symptomatic gallstones, although there are other indications for the procedure, including carcinoma....