Tag: functions of the liver

Glycogen is a branched polysaccharide of glucose molecules that serves as the primary short-term energy storage carbohydrate in animals, being abundantly synthesized and stored in liver and muscle cells.

Instead of accumulating inside the muscle cells, lactate produced by anaerobic fermentation is taken up by the liver. This initiates the Cori cycle. In the liver, gluconeogenesis occurs, which reverses both glycolysis and fermentation by converting lactate first into pyruvate, and finally back to glucose. The glucose is then supplied to the muscles through the bloodstream. If muscle activity has stopped, the glucose is used to replenish the supplies of glycogen through glycogenesis.

Liver is the largest gland in the body. It is a digestive gland present at the left half of the digestive system besides stomach. It synthesises bile, which emulsify (breaking into small droplets) fats and increase the surface area for the action of lipase enzyme.

The fat in the human diet is in the form of triglycerides. To use the fat as a source of energy for the body it needs to be broken down - a process referred to as fat metabolism.  This metabolism which takes place primarily in the liver gives out cholesterol and phospholipids. These are made available to the rest of the body along with lipoproteins and the rest are excreted out through bile. Thus, the correct answer is option D.

Once glucose is inside the liver, glucose is phosphorylated into glucose-6-phosphate, or G6P. G6P is further metabolized into triglycerides, fatty acids, glycogen or energy. Glycogen is the form in which the body stores glucose. The liver can only store about 100 g of glucose in the form of glycogen. 

The glucose stored in the liver serves as a buffer for blood glucose levels. Therefore, if the blood glucose levels start to get low because person has not consumed food for a period of time, the liver is able to release glucose into the bloodstream to maintain healthy levels. If the body reserves of glucose deplete, a process called gluconeogenesis will take place. During gluconeogenesis, glucose is synthesized from molecules that are not carbohydrates. 

Liver is the largest gland of the body weighing about 1.2 to 1.5 kg in an adult human. It is situated in the abdominal cavity, just below the diaphragm and has two lobes. The hepatic lobules are the structural and functional units of liver containing hepatic cells arranged in the form of cords. Each lobule is covered by a thin connective tissue sheath called the Glissons capsule. The bile secreted by the hepatic cells passes through the hepatic ducts and is stored and concentrated in a thin muscular sac called the gall bladder. The duct of gall bladder (cystic duct) along with the hepatic duct from the liver forms the common bile duct. The bile, pancreatic juice and the intestinal juice are the secretions released into the small intestine. The bile released into the duodenum contains bile pigments (bilirubin and biliverdin), bile salts, cholesterol and phospholipids but no enzymes. Bile helps in emulsification of fats, i.e., breaking down of the fats into very small micelles. Bile also activates lipases. Fats are broken down by lipases with the help of bile into di-and monoglycerides.

Liver is the largest gland of human body that accomplishes a diverse set of functions. Liver is known as chemical factory of the body. Most of the biochemical functions of the body are done by the liver. Detoxification is a major function of liver. Thus, conversion of toxic substances into non-toxic substances is done by liver. The toxic substances include xenobiotic compounds or may be formed by metabolic activities of the body. e.g., Prussic acid is converted into Potassium sulfocyanide (it is a non-toxic salt) by the liver.

Steroids like cholesterol are crystallisable lipids having four hydrocarbon rings, consisting of three cyclohexane and one cyclopentane ring and a long hydrocarbon side chain. In animals,  liver is the major site of cholesterol production. Cholesterol is an important constituent of bile produced in liver.

One of the most important biochemical roles of liver is detoxification i.e., conversion of toxic substances into non-toxic substance. The toxic substances cab be foreign or xenobiotic compounds or are formed by metabolic activities of the body. One of the detoxification strategies of liver is to make the xenobiotic and harmful chemicals water soluble by hydroxylating them. Once hydroxyl group is added, the chemicals become water soluble and can be easily excreted through urine route.