Digestive glands1. The gall or bile is a yellow-greenish liquid deposited in the pear-shaped gall bladder. It is made of water, cholesterol, biliary salts and biliary acids, necessary for digestion, but also liver waste products, like biliary pigments and extra-cholesterol eliminated from the organism. The hormone cholecystokinin causes the release of the bile through the biliary duct into the duodenum (small intestine). If there is no food in the intestine, a valve called Oddi sphincter remains closed, retaining the bile into the bladder.
2. Bile is required for digesting fats; without it, we would just poop the fats. The biliary salts mix with the fats turning them into an emulsion, a liquid containing small suspensions of fat particles. The liver produces about one liter of bile daily, but the bile bladder cannot store more than 0.41 liters. That's why it concentrates up to 20 times the bile produced by the liver, much of the water re-entering the blood. The resulting dense, sticky liquid is stored in the extended bladder.
3. Normally, the cholesterol stays liquid, and cannot form deposits. But, if the composition of the bile modifies, cholesterol crystals can form. They are likely to combine with biliary salts and pigments producing gallstones, which are yellow-greenish and of variable sizes, up to 500 g (1.1 pounds). Gallstones can be made exclusively of cholesterol or exclusively of biliary pigments. Gallstones appear especially in persons eating large amounts of food rich in saturated fatty acids (animal fat) and they are thrice more frequent in women than men. Smaller gallstones can pass smoothly to the intestine, without causing problems, but the large ones can get stuck into the biliary duct. If they obstruct the duct, they can cause severe issues and pain.
4. Liver is the largest human gland: 1.4 kg (3 pounds). It is the organ most exposed to toxins, because, during the metabolism, nutrients-filled blood passes through it first. Still, even when 75 % of the organ is harmed, the liver can still function normally. Liver cells have an enormous regenerative power and can rebuild the whole organ once the source of poisoning was been removed.
5. Liver is the recycling center of the body. Blood's red cells live about 100 days and dead red cells decompose. Their reusable parts are retained by the hepatic cells and the useless parts, like the pigment called bilirubin, are eliminated with the bile (this pigment colors the human feces in brown). If the liver's function is impaired or the biliary duct is obstructed so the bilirubin cannot be removed out of the body, the yellow-golden pigment accumulates into the blood causing jaundice. In this case, the pigment stored in the skin and eyes colors them in a yellowish hue.
The body also reuses about 3-4 grams of biliary salts, which enter from the intestine to the blood, and via blood, they reach back the liver.
6. Liver processes all the nutrients absorbed from the food into chemicals that can be used by the organism. Carbohydrates are absorbed by the organism as simple sugars, like glucose, fructose, galactose. The other tissues can use only the glucose, that's why the liver, with its enzymes, transforms them all into glucose. If there is a sudden requirement of energy, the liver releases glucose into the bloodstream. The extra glucose is turned into a carbohydrate polymer, glycogen, deposited into the liver and muscles, and if these deposits are filled, the glucose is deposited as fat into the fatty tissue under the skin. If energy consume increases, glycogen and fats are reverted to glucose.
Liver also serves as storehouse for iron and vitamins A, D and B12. Unfortunately, the liver also stores toxins, like pesticides. Some toxins are broken down into the liver: strychnine, nicotine, alcohol or barbituric. But liver's capacity to detoxify poisons is not limitless. Too much alcohol for too long affects the liver's cells capacity to regenerate, and they will be replaced by scar tissue. This is cirrhosis, that can kill if untreated.
7. The pancreas has a double function: produces digestive juices for breaking down sugars, proteins and fats and insulin, a hormone controlling the blood sugar level. This organ secretes 1.2-1.5 liters of pancreatic juice daily, drained into the duodenum through the pancreatic duct. The juice is produced as soon as we start eating. Two hormones released by the duodenum, secretin and pancreozymin, cause the release of the pancreatic juice. The pancreatic juice is alkaline, causing the neutralization of the acid juices that come from the stomach, allowing the intestine juices to work. The pancreatic juice contains 5 digestive enzymes: 3 for breaking down proteins, as well as amylase (for breaking down sugars) and lipase (the only enzyme produced by the body that digests fats). The lipase acts on the small fat particles prepared by the bile.
The pancreatic digestive enzymes are the most powerful and, to avoid auto-digestion, the pancreas synthesize them inactive, being activated inside the intestine.
8. The pancreas produces two hormones: insulin and glucagon. They are produced by groups of cells called the islets of Langerhans. The two hormones work oppositely one to another: glucagon raises the level of blood sugar, speeding up the release of glucose into the bloodstream, while the insulin lowers the levels of the blood sugar, stimulating the tissues to extract it from the bloodstream. Any imbalance between the two hormones causes diabetes, a potentially killer disease.