What are the functions of liver and pancreas in the human digestive system ?
The liver is the largest gland or chemical factory in the body. It is like a sponge shaped like a wedge. It has many metabolic and secretory functions. It produces a digestive fluid called bile, which is important in facilitating fat digestion and absorption of fat.
It stores vitamins and glycogen (a polysaccharide, that is the main form of carbohydrate storage in animals and occurs primarily in the liver and muscle tissue. It is readily converted to glucose as needed by the body to satisfy its energy needs. Also called animal starch).
Some of its other tasks are;
The liver produces and releases about 800 and 1,000 ml of bile each day. Bile is also a gateway for the excretion of toxic substances such as drugs. A duct carries the bile to the common bile duct, which pours the bile into the duodenum (first section of the small intestines). The ducts are also connected to the gallbladder where the bile is concentrated and stored. Used red blood cells, which are called senescent red blood cells, are destroyed in the liver, spleen, and bone marrow. Bile is a greenish orange colour because of the pigment bilirubin, which is made by the breakdown of haemoglobin (the iron-containing respiratory pigment in red blood cells).
Liver cells produce a number of enzymes. When blood flows through the liver, the cells and enzymes are filtered. Nutrients that come into the liver through the intestines are converted so they can be used by cells and stored more easily.
1. Fats --> Fatty acids-->Carbohydrates or ketone bodies
2. Sugars --> Glycogen (stored in the liver until energy production --> glucose)
The liver produces blood serum proteins and many clotting factors.
The liver metabolizes nitrogenous waste products and detoxifies poisonous substances, making them ready for excretion through urine or feces.
The pancreas is a gland which releases digestive enzymes and hormones. It has functions both in the digestive system and the endocrine system. The pancreas is about 17.8 cm in length and 3.8 cm wide. It is under the stomach and it is attached to the small intestine, specifically to the duodenum (first section of small intestines). Pancreatic tissue is made up of grapelike clusters of cells that synthesize a clear liquid called pancreatic juice, which reaches the duodenum through the common bile duct which is also used by the liver to secrete bile. It contains three very important enzymes:
Among the enzyme producing acinar cells, endocrine cells are present in clusters called the islets of Langerhans. There are three types of endocrine cells (beta, alpha, and delta cells) in the Islets of Langerhans, which make the 1-2 per cent of pancreas mass. Beta cells are the cells that make insulin, and alpha cells make glucagon. Delta cells produce a local hormone somatostatin that regulates the secretion of both insulin and glucagon.
In summary, the pancreas secretes two important hormones:
These hormones insulin and glucagon work together to regulate blood sugar. After the meal, insulin lowers the amount blood sugar, but it increases the amount of glycogen (a stored format of carbohydrates) in the liver or storage of fat in fat (adipose) tissue. Glucagon does the reverse of insulin. Between meals, it increases blood sugar by facilitating the breakdown of stored glycogen in the liver.