Gallbladder is a small muscular organ which stores gall, a fluid of specific greenish-yellow color. This fluid is an important digestive fluid created by the liver. Gall flows out of the liver through left and right hepatic tract, which are both connected to create one unified hepatic tract in the other end. This tract is then connected with the water coming out of the gallbladder, also known as the cyst line to make a unified gall lead. This fluid then enters the upper part of the intestines, right next to the Oddie’s sphincter, a couple of inches below the stomach.
About half of the extracted gall in between meals goes through the cyst lead into the gallbladder. The rest of the gall flows closely through the unified gall lead into the thin intestines. When you eat the gallbladder contracts, empties its gall into the intestine to help digest fats and some vitamins. Gall is made out of gall salts, electrolytes, and some gall pigments like bilirubin, cholesterol and other fats like lipids. It is also responsible for disposal of some waste matter out of the organism, especially pigments found in destroyed red blood cells as well as excess of cholesterol. It helps in digestion and absorption of fat as well. The gall salts increase the dissolving properties of cholesterol, fats and some vitamins which make it easy for your intestines to absorb them. Hemoglobin from the destroyed blood cells is then turned into bilirubin which is the main pigment of gall.
The main function of gallbladder is to help emulsify fats from the food you take. An anion of gall salts has a hydrophilic and hydrophobic part, which means that it is capable of surrounding and separating drops of fat like triglycerides and phospholipids. This creates the so called micelle, which have their hydrophobic part turned to the inside, and the hydrophilic towards the outside of the cell. The latter also carries a positive electric charge, which prevents drops of fat to group into bigger cells. Micelles usually come in at 15-30 micrometers in diameter.
Dispersion of fat from the food into micelles provides a bigger surface area for the enzymes to do their mission of dissolving triglycerides and can reach into the fat core through the cavities in between gall salts. Triglycerides are always dissolved into two different fat acids and monoglyceride, which are absorbed in the walls of your intestines. Once they reach through the membrane, fat acids start to form triglycerides again and are absorbing themselves into the lymph system through the lymph capillaries. With no gall salts, most of the lipids found in food would come out of the body as feces, without being dissolved.
Since gall improves fat absorption, it has a significant role of absorbing substances contained in fats as well – these are vitamins (mainly D, E, K and A). Also, gallbladder carries another important function of being the main organ producing bilirubin which is recycled by the liver. Gall salts themselves have an important role of destroying many microorganisms in food you take, as well.