What is Gallbladder? Structure, embryonic development, functions and diseases related to gallbladder.

 GALL BLADDER

Introduction

Digestive system is the means by which tissues and organs receive nutrients to function. The system breaks down food, extracts nutrients from it and converts them into energy. The digestive system allows us to utilize food from diverse sources as meat from an animal and the roots of the plant and utilize them as an energy source. Our digestive system allows us to manage the process without much thought and often while performing other tasks. The process of digestive system is the complex one that takes the food we place in our mouth and turns it into energy and waste products. This process takes place in the gastrointestinal tract. The food is propelled forward within the system, altered by enzymes and hormones into usable particles and absorbed along the way. Other organs that support the digestive process are liver, gallbladder and pancreas. Gallbladder is a small pouch that sits just under the liver. The gallbladder stores bile produced by the liver. Bile made in the liver travels through the small intestine via the bile ducts. If the intestine does not need it, the bile travels into the gall bladder. After meal the gallbladder is empty and flat, like a balloon. Before a meal, the gallbladder is full of bile and about the size of a small pear. Bile helps digest fats, but the gallbladder itself is not essential. Bile serves two main purposes. First, it helps absorb fats in the diet and secondly, it carries waste from the liver that cannot go through the kidneys. As a whole the structure of gall bladder are divided into following parts:

• Fundus - the rounded distal portion of gall bladder 
• Body - the largest part of gall bladder
• Neck - the gall bladder tapers to become continuous with a cystic duct, leading into the biliary tree.

The bile ducts are usually divided into intrahepatic and extrahepatic part. The bile ducts originate from the bile canaliculi, which do not have their epithelium. Their lumen is solely formed by the apical poles of the hepatocytes. Due to this the apical side of the hepatocytes is also referred to as the peribiliary cell pole. At the edge of liver lobule, bile reaching small connecting ductules and then the interlobular bile ducts in the periportal fields. They have a diameter of roughly 40 micro meter and run alongside the branches of portal hepatic vein and portal hepatic artery. The extrahepatic bile ducts begins with the fusion of the right and left hepatic duct which forms the common hepatic duct. It runs roughly 4cm in the caudal direction at the lower edge of liver. It gives rise to the cystic duct which leads bile to the gall bladder. At this position, the hepatic duct becomes the common bile duct, which runs towards the duodenum for roughly 6cm. At its distal end and just before its fusion with the pancreatic duct, the bile duct contains a circular muscle, the sphincter muscle of the bile duct. The gall bladder receive most of its blood supply from the 

 

• Cystic artery - a branch of the right hepatic artery and venous drainage of the neck of the gall bladder is the

• Cystic vein - which drain directly into the portal vein 

On the other hand nerve supply of the gall bladder is provided by the following nerves:

• vagus nerve

• celiac plexus

Lymphatic drainage of gall bladder drains into the intrahepatic lymph vessels, while others will empty to the cystic node. The caudal part of the biliary tree drains to the superior pancreaticosplenic and inferior hepatic nodes. 

Embryonic Development of Gall Bladder 

The gall bladder from which it develop during the time of embryonic development is the midgut. The first primordium organ of bile ducts and the liver is hepatic diverticulum or liver bud. It starts as a thickening of endoblastic epithelium in the ventral wall of the anterior portion of the foregut. From the ventral and lateral surfaces of the diverticulum, on which the endoderm is in contact between the pericardial and peritoneal cavities, endodermal cells extend into the septum transversum to form the earliest primordium organ of the liver. In the embryo, approximately 5mm in length, the diverticulum also shows a bud in its distal part. The bud grows in length and represents the primordium organ of the gall bladder, the cystic duct and common bile duct. For up to 8 weeks of incubation, the extrahepatic biliary tree develops through length of the hepatic diverticulum. This structure is patent from the beginning and remains patent and in continuity with developing liver. At 29 days after fertilization, the gall bladder primordium organ is visible as a right anterolateral dilation along the distal part of the hepatic diverticulum, with a cystic duct. At that stage, the cystic duct and gall bladder are provided with a lumen. In the 34 day embryo, the common hepatic duct is broad and funnel like structure in contact with the liver. During the fifth week, the proliferation takes place in the dilated funnel shaped structure. During the 7 week of the embryonic development, no intrahepatic duct system is developed in the liver. 

Functions of Gall Bladder

As gall bladder is a part of digestive system, it perform several functions. The main function of gall bladder is storage and concentration of hepatic bile. It also includes modification of biliary lipid concentrations and secretion of proteins. Cholesterol and bile salts are actively transported by the gall bladder. The gall bladder keeps aware to and responds to the biliary environment. The gall bladder provides and ideal system to study a variety of cellular transport systems, the features of which are shared with its neighbors, the liver, the small intestine and the kidneys. The interactions that take place at the plasma membrane of the gall bladder with bile are likely to have relevance for protein mediated events. Gall bladder motor function is regulated by bile acids via the membrane bile acid receptor, e.g; cholecystokinin intestinal hormones. The cycle of gall bladder is to filling and emptying controls the flow of bile into the intestine. The gall bladder secretes mucins and bicarbonates which both provide protection against bile acids. The gall bladder also functioned as a concentrating reservoir for bile, which it delivers to the duodenum.

Problems Of Gall Bladder 

If there will be disturbance in any organ it will show abnormality. Gall bladder also shows abnormalities and the most common gall bladder problem is Gall stones. Gall stones are the hard lump of material that can form in your gall bladder. They can be made up of bile salts or a cholesterol called bilirubin. Having two much cholesterol in your bile can lead to yellow cholesterol stones. Pigment gall stones produced when your gall bladder cannot break down the excess bilirubin. Several risk factors include,

• eating diet high in fat or cholesterol
• carrying excess weight 

several common symptoms that are shown in the body as a result of gall stone problem are as following:

• gall bladder pain 
• nausea 
• vomiting 
• bloating 
• indigestion 
• diarrhea 
• stomach pain
• dark urine
• low grade fever

most of the time you won't need treatment for gall stones unless they cause pain. Sometimes you can pass gallstones without even noticing. If you are in severe pain, doctor will recommend surgery. And the other, some nutritional supplements you can take include

• vitamin C
• iron 
• lecithin
• fresh fruits 
• lemon juice 
• olive oil
• fresh vegetables 
• focus on fibers 
• fish oils 
• limit sugary and fatty foods

where as some other disorders of gall bladder are as following:

• Cholecystitis
• choledocholithiasis
• gall bladder polyps
• gall bladder cancer
• perforation
• gall bladder abscess
• porcelain gall bladder
• pancreatitis 

Choledocholithiasis

Choledocholithiasis is a condition or disorder of gall bladder in which gallstone occurs. It only happens when gallstone block the common bile duct. People who with choledocholithiasis experience pain in the upper right part of abdomen. Common symptoms of choledocholithiasis are as following:

• jaundice
• nausea
• vomiting
• loss of appetite
• fever
• abdominal pain

the main causes of choledocholithiasis are as following:

• too much cholesterol
• too much bilirubin 
• not enough bile salts 

to diagnose choledocholithiasis, following tests are used:

• abdominal CT scan 
• MRI
• X-ray of the bile ducts
• liver function tests
• blood test

Cholecystitis

Cholecystitis is a condition or disorder of gall bladder in which there is an inflammation of gall bladder. Gall stones are the most common cause of the cholecystitis. Bile can build up in the gall bladder if gallstones obstruct the bile ducts. It leads to inflammation. This condition can be acute as well as chronic. Some of the symptoms of cholecystitis are as following:

• nausea
• vomiting 
• fever 
• abdominal pain 
• bloating 
• yellowing the skin 
• chills

to diagnose cholecystitis, following tests are used:

• CT scan 
• ultrasound 
• hepatobiliary scintigraphy
• cholangiography 
• liver function tests
• CBC test

Pancreatitis 

Pancreatitis is a disorder of the gall bladder in which there is an inflammation of pancreas. This condition can also be acute as well as chronic. Symptoms of pancreatitis may include:

• nauseas
• indigestion 
• vomiting 
• fever 
• pain 
• weight loss 

some of the acute and chronic pancreatitis causes are as following:

• gallstones 
• drinking a lot of water 
• pancreatic cancer 
• infections 
• abdominal surgery 
• cystic fibrosis

to diagnose pancreatitis, following tests are used:

• pancreatic function test

Healthy diet plays major role in recovering from pancreatitis. Try to limit or avoid the following foods:

• fried food
• caffeine
• alcohol
• sugar deserts