Gallbladder

From Encyclopedia Jr, free information reference for Kids

The gallbladder (or cholecyst sometimes gall bladder) is a pear-shaped organ that stores about 50 mL of bile (or "gall") until the body needs it for digestion. The gallbladder is about 7-10cm long in humans and is dark green in appearance due to its contents (bile), not its tissue. It is connected to the liver and the duodenum by the biliary tract.

Contents 1 Microscopic anatomy 2 Function 3 Role in disease 3.1 Cholestasis 3.2 Biliary colic 3.3 Cholelithiasis 3.4 Cholecystitis 3.5 Choledocholithiasis 3.6 Gallstone ileus 3.7 Gallbladder cancer 3.8 Gallbladder Polyps and Primary Sclerosing Cholangitis 4 Additional images 5 External links

[edit] Microscopic anatomy

The gallbladder has an epithelial lining characterized by recesses called Aschoff's recesses, which are pouches inside the lining. Under the epithelium there is a layer of connective tissue, followed by a muscular wall that contracts in response to cholecystokinin, a peptide hormone secreted by the duodenum.

[edit] Function

The gallbladder stores bile, which is released when food containing fat enters the digestive tract, stimulating the secretion of cholestoscystokinin (CCK). The bile emulsifies fats and neutralizes acids in partly digested food. After being stored in the gallbladder, the bile becomes more concentrated than when it left the liver, increasing its potency and intensifying its effect on fats.

[edit] Role in disease

[edit] Cholestasis

Cholestasis is the blockage in the supply of bile into the digestive tract. It can be "intrahepatic" (the obstruction is in the liver) or "extrahepatic" (outside the liver). It can lead to jaundice, and is identified by the presence of elevated bilirubin level that is mainly conjugated.

[edit] Biliary colic

This is when a gallstone blocks either the common bile duct or the duct leading into it from the gallbladder. This condition causes severe pain in the right upper abdomen and sometimes through to the upper back. Other symptoms are nausea and vomiting, diarrhea, bleeding caused by continuous vomiting, and dehydration caused by the nausea and diarrhea. Another more serious complication is total blockage of the bile duct which leads to jaundice, which if it is not corrected naturally or by a surgical procedure can be fatal as it causes liver damage. The only long term solution is the removal of the gall bladder.

[edit] Cholelithiasis

Main article: Cholelithiasis

Up to 25% of all people have gallstones (cholelithiasis), composed of cholesterol, lecithin and bile acids. These can cause abdominal pain, usually in relation with the meal, as the gallbladder contracts and gallstones pass through the bile duct. Many physicians describe this pain as "colicky"; however, this is not the case as the biliary tree does not have peristalsis and therefore the pain does not come and go. Instead, the pain is usually constant, lasting several hours and can radiate to the shoulder. Surgery (cholecystectomy, removal of the gallbladder) is the most common treatment for gallstones. It can be performed laparoscopically, and it is in fact one of the most common procedures done through the lapae. People traditionally considered at an increased risk of cholelithiasis are people who are 5 F's:

• Female
• Fat (obesity)
• Fair (Caucasian, but this is disputed by recent studies)
• Forty (middle-aged)
• Fertile (multiple children)

[edit] Cholecystitis

Main article: Cholecystitis

Acute or chronic inflammation of the gall bladder causes abdominal pain. 90% of cases of acute cholecystitis are caused by the presence of gallstones. The actual inflammation is due to secondary infection with bacteria of an obstructed gallbladder, with the obstruction caused by the gallstone.

[edit] Choledocholithiasis

Main article: Choledocholithiasis

When gallstones obstruct the common bile duct, the patient develops jaundice and liver cell damage. It is a medical emergency, requiring endoscopic or surgical treatment.

[edit] Gallstone ileus

A rare clinical entity is ileus (bowel obstruction) by a large gallstone, or gallstone ileus. This condition develops in patients with longstanding gallstone disease, in which the gallbladder forms a fistula with the digestive tract. Large stones pass into the bowel, and generally block the gut at the level of Treitz' ligament or the ileocecal valve, two narrow points in the digestive tract. The treatment is surgical.

[edit] Gallbladder cancer

Cancer of the gallbladder is a rare but highly fatal disease. It has been associated with gallstone disease, estrogens, cigarette smoking, alcohol consumption and obesity. Despite aggressive modern surgical approaches, advanced imaging techniques, and endoscopy, nearly 90% of patients die from advanced stages of the disease and experience pain, jaundice, weight loss, and ascites.

[edit] Gallbladder Polyps and Primary Sclerosing Cholangitis

Polyps (growths) are sometimes detected during diagnostic tests for gallbladder disease. Small gallbladder polyps (up to 10 mm) pose little or no risk, but large ones (greater than 15 mm) pose some risk for cancer, so the gallbladder should be removed. Patients with polyps 10 mm to 15 mm have a lower risk but they should still discuss removal of their gallbladder with their physician. Of special note is a condition called primary sclerosing cholangitis, which causes inflammation and scarring in the bile duct. It is associated with a lifetime risk of 7% to 12% for gallbladder cancer. The cause is unknown, although primary sclerosing cholangitis tends to strike younger men who have ulcerative colitis. Polyps are often detected in this condition and have a very high likelihood of malignancy.

[edit] Additional images

The celiac artery and its branches; the liver has been raised, and the lesser omentum and anterior layer of the greater omentum removed.

Transverse section of gall-bladder.

Topography of thoracic and abdominal viscera.

[edit] External links

• MedlinePlus Image 19261
• Gallbladder Disease at allrefer.com
• MedlinePlus Encylopedia 000264 - Acute cholecystitis
• eMedicine med/833 - Gallbladder Cancer
• "How Serious are Gallstones and Gallbladder Disease?" at umm.edu
• Histology at KUMC epithel-epith05 "Gall Bladder"
• SUNY Labs 38:14-0100 - "Stomach, Spleen and Liver: The Gallbladder and the Bile System"
• SUNY Anatomy Image 7763

Digestive system
Gastrointestinal tract: Mouth | Pharynx | Esophagus | Crop | Stomach | Small intestine (duodenum, jejunum, ileum) | Vermiform appendix | Large intestine (Cecum | Colon | Rectum | Anal canal) | Anus Accessory organs: Pancreas | Gallbladder | Liver | Ducts: (Cystic duct | Common hepatic duct | Pancreatic duct | Bile duct | Common bile duct | Hepatopancreatic ampulla )