Gallbladder is a significant organ of the digestive system that is able to store and accumulate the bile, which helps to break up the fat molecule into smaller ones. Located under the liver and the right side of the abdomen, the gallbladder exists as a portion of the biliary tract. The gallbladder is an intriguing organ and has been studied by scientists for a long time. Even though the gallbladder is not extremely necessary compared to other organs within the digestive system, it still has particular functions that help with digestion. In addition, the gallbladder could potentially provoke symptoms, such as gallstones, gallbladder attack, and gallbladder disease that cause abdominal pain. Cholecystectomy can help to forestall the development of gallbladder cancer.
Structure and Function
The gallbladder connects the liver and the small intestine.  The size of the gallbladder alters along with the growth of a person. The gallbladder in an adult is roughly 3.1 inches in length and 1.6 inches in width while it is fully swollen. Hence, the size of a gallbladder is close to a potato. The function of the gallbladder is to store bile and discharge bile when fat molecules enter the gallbladder. After the bile breaks down the fat, they will enter the small intestine. The gallbladder helps to digest efficiently. If someone removes his gallbladder, he has to be vigilant of his eating habits to minimize the chance of eating fat acids.  The gallbladder reserves the bile during the time it does not need to enter small intestine. This reveals stimulation and secretion as other functions of the gallbladder. When the cells of gallbladder detect proteins or fatty acids, duodenum will react to this reception by stimulating the hormone cholecystokinin, which enters to the gallbladder and triggers the smooth muscle tissue of the walls of the gallbladder.  Before the food enters the small intestine, cholecystokinin, a peptide hormone in the digestive system, releases from the upper small intestine to give a sign to the gallbladder to release the bile through the common bile duct. 
Bile is a specialized enzyme, secreted by the liver that is essential for the digestion of fats, combined with fat, fluid, and cholesterol. Through the gallbladder, the food molecules which have been disassembled by bile will then enter the small intestine. The small intestine serves as the place in which digestion takes place. Due to its exclusive function, bile can help break down fat and permits vitamins, which can dissolve in the fat solvent, and nutrients entering the bloodstream efficiently to be absorbed.  The bile also carries waste products of food from the liver and to the duodenum of the small intestine.  Additionally, the hormone cholecystokinin arouses the smooth muscle tissue of the gallbladder, imposing bile to come out of the gallbladder into the cystic duct. 
Problems and Symptoms
There are many different gallbladder-related illnesses. Nowadays, doctors are able to treat these diseases effectively, and these different gallbladder illnesses are known as gallstones, polyps, perforation, abscess, and porcelain. Here are some specific illustration of these common diseases:
Gallstones are hardened particles, consisting of cholesterol, the combination of bile salts, and bilirubin. The excessive cholesterol secreted by the liver is carried to the gallbladder solidifies, resulting in the formation of gallstones. The size of gallstones may vary depending on the time it formed and the amount of superfluous cholesterol. They cause extreme pain inside one's body. Doctors may use Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) to detect the stones in the patient's gallbladder. There are two different kinds of treatment depending on the location of gallstones. 
Gallstones in the gallbladder
Doctors usually suggest patients have surgery to remove the gallbladder. Doctors perform this operation by utilizing laparoscope, a kind of flexible viewing tube. Instead of starting the cutting into the dermis, they enact the incisions in the abdomen in order to diminish the discomfort and the size of the scar. If the gallstones are not considerable, having the surgery may seem unnecessary. The Doctor may suggest his patients take some drugs-ursodeoxycholic acid-to self-dissolve these gallstones. 
Gallstones in the bile ducts
During ERCP (Endoscopic Retrograde Cholangiopancreatogram), doctors usually utilize a special tool to cut the sphincter of Oddi after it crosses the endoscope. Then doctors employ catheters to collect and remove the stones from the duct. This procedure is called endoscopic sphincterotomy. Usually, doctors can perform this procedure on ninety percents of patients successfully. 
The majority of gallbladder polyps are benign because they are just polyps that are comprised of cholesterol. In fact, these polyps can potentially become cancerous tumors. Small gallbladder polyps are usually noncancerous, so people do have to eliminate from their gallbladder, but if the polyps consistently grow without halting, they can penetrate the inner wall of the gallbladder. It is still rare to increase the risk of getting cancer if the length of the polyps is less than 0.5 centimeter. In common situation, the polyps will not jeopardize people's life; however, if the gallbladder polyps continue to grow and become larger, there is possibility for them to have pathological changes and even cause serious danger, such as cancer. Hence, if the size of polyps is bigger than one centimeter, there is a higher possibility for the polyps to transform to cancerousness. When the gallbladder polyps are longer than 1.5 centimeters, the possibility of having cancers will increase to forty-six to seventy percentage. At that time, if the patients need to remove the polyps, the doctors have to take higher risk performing the procedure to remove them. 
The bladder perforation usually happens a few days or months after excruciating cholecystitis (inflammation of the gallbladder). Dr. Yuranga Weerakkody notes the reason this happens is "[the] perforation is thought to result from occlusion of the cystic duct (most often by a calculus) with resultant retention of intraluminal secretions. Distension of the gallbladder with a consequent rise in intraluminal pressure can impede venous and lymphatic drainage, leading to vascular compromise and ultimately to necrosis and perforation of the gallbladder wall." There are four different types of gallbladder perforation: type I, II, III, and IV. In fact, gallbladder stones can result in gallbladder perforation that becomes a menace for one's life. If gallbladder perforation is not detected timely, it can induce enormous troubles in humans' bodies.Thus, it will definitely be better for someone to receive a formal treatment for gallbladder perforation rather than endure the pain and neglect it. Doctors usually use CT of ultrasound to detect the perforation. The perforated gallbladder generates some complications as well, such as pancreatitis and pneumonia. 
Abscess of the Gallbladder
Sometimes the Gallbladder abscesses following cholecystitis (inflammation) and is called empyema. The pus consists of dead tissue, white blood cells, and bacteria that causes enormous pain in the stomach, and even engenders higher risk of threatening one's life. Usually, the abscess of the gallbladder situates in the abdominal wall where either between the sub-hepatic or between the space of etroperitoneum inferior and sub-hepar. This symptom could result from the complication of laparoscopic cholecystectomy. 
Porcelain gallbladder is the kind of gallbladder that has undergone calcification to make the walls of gallbladder rigid. The porcelain gallbladder is an unusual symptom of chronic cholecystitis. The word "porcelain gallbladder" means the discoloration and calcification of gallbladder. People who have porcelain gallbladders are possible to have cancellation of gallbladder. However, when people have porcelain gallbladders, there is no obvious symptom about the indicative health problems. The scientist have not figure out the exact possibility of someone gets porcelain gallbladder, but they estimate the number could between 0.6-0.8%; in addition, the morbidity among different genders can also be different: the possibility for a male to get the porcelain gallbladder to the possibility for a female is one to five. Around ninety percent of porcelain, the gallbladder is related to gallstones. The porcelain gallbladder can be detected by normal X-ray or ultrasonography, which can reconstruct the image of its area. 
People may claim that the gallbladder is a useless organ that people are able to live without it. Some doctors state that it will be okay to remove gallbladders from people's bodies. In reality, every organ possesses diverse effects that cooperate to run human's system normally. Even though the evolutionists insist that the gallbladder is the remnant from human's evolution that is dispensable, God designed each part of our bodies for a special purpose. His creation helps people to deal with different situations. The gallbladder plays an important role in human's digestive system, and it does not serve as a vestigial organ. Like a machine, the human body will not work perfectly if missing one part of the machine. If someone' gallbladder is removed, there will be no place for storing and concentrating bile. The secretion of bile will not be affected due to the production from the liver, but the concentration of bile will become thicker and the time to release bile is sporadic. Under common circumstances, a person can perform digestion well without the gallbladder; however, it is still better to keep gallbladder due to its particular functions. The evolutionary perspective erodes people's minds that induce them to challenge the concepts of His perfect creation.  However, if people have to remove their gallbladders due to diseases, here are some suggestion for these people:
1. Have a low-fat diet;
2. Better eat a frequent meal with less food than eat three big meals per day;
3. If one fast for a lone time, he'd better not eat a big meal after that. 
This video mainly talks about the location, function, parts, lymphatic drainage, vascular system, and nervous supply of gallbladder.
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