Liver and bile juice

Liver 

  • Liver  is the largest gland of our body.
  • It is located in right side of upper abdominal cavity just below the diaphragm.
  • It is an important gland which plays both excretory and secretory functions.
  • It is the largest gland having weight 1.5 kg.
  • Liver is made up of many lobes called Hepatic Lobes.
  • Each hepatic lobe consists of many lobules called Hepatic lobules.
  • Hepatic lobule is the structural and functional unit of liver.
  • About 50,000 to 100,000 lobules present in the liver.
  • These lobule are Honeycomb like structure and it is made up of liver cells called Hepatocytes.

human liver, bile, bile juice

Hepatocytes and hepatic plates

  • Hepatocytes are arranged in columns which form the Hepatic Plates.
  • Each plate is made up of two columns of cells.
  • In between the two columns of each plate lies a bile canaliculus.
  • In between the neighboring plates, a blood space called SINUSOID is present.
  • Sinusoid is lined by the endothelial cells. In between the endothelial cells some special macrophages called Kupffer cells are present.
  • Bile is secreted by hepatic cells and emptied into Bile Canaliculus.
  • From canaliculus, the bile enters the tributary of bile duct.
  • Tributaries of bile duct from canaliculi of neighboring lobules unite to form small bile ducts.
  • These small bile ducts join together and finally form left and right hepatic ducts which emerge out of liver.


Bile

Bile is the juice secreted by hepatic cell from the liver and stored in the gallbladder.
Bile play an important role in the digestion of food and absorption of nutrients in small intestine.

Biliary system

  • Biliary system is formed by combination of gallbladder and hepatic ducts (outside the liver).
  • Right and left hepatic bile ducts which come out of liver join to form common hepatic duct.
  • It unites with the cystic duct from gallbladder to form common bile duct.
  • Common bile duct unites with pancreatic duct to form the common Hepatopancreatic duct or Ampulla of vater, which opens into the duodenum.
  • One sphincter called Sphincter of oddi at the lower part of common bile duct, before it joins the pancreatic duct.
  • It is formed by smooth muscle fibers of common bile duct.
  • It is normally kept closed; so the bile secreted from liver enters gallbladder where it is stored.
  • On particular stimulation, the sphincter opens and allows flow of bile from gallbladder into the intestine.

    

Properties of bile

  • Volume: 800-1200ml/day
  • Reaction: alkaline
  • pH: 8 - 8.6
  • Specific gravity: 1.010-1.011
  • Colour: Golden yellow and Green 


Composition of bile juice

Bile contains 97.6% of water and 2.4% of solids.
Solids- organic and inorganic substances.

Organic substances-
  • Bile salts
  • Bile pigments
  • Cholesterol
  • Fatty acids
  • Lecithin
  • Mucin

Inorganic substances- 
  • Calcium
  • Sodium
  • Bicarbonate
  • Chloride
  • Potassium
Bile juice contains large quantity of bile salts, bile pigments, cholesterol, lecithin and fatty acids.

Storage of bile

Bile juice is stored in the gallbladder.
It is released from the gallbladder into intestine.
When bile is stored in the gallbladder it undergoes into various changes in quality and quantity.
Volume is decreased because of absorption of water and electrolytes.
So the PH decreased slightly of bile salts, bile pigments.

 Function of bile salts

1. Digestive function- Bile salts are required for the digestion and absorption of fats in intestine. 
With the help of bile salts fats are emulsified into minute droplets in small intestine.
2. Absorption function- Bile salts help in digestion and absorption of fats from intestine into blood.
3. Choleric action- Bile salts stimulate the secretion of bile from liver.  
4. Laxative agent- Bile salts act as laxatives by stimulating peristaltic movements of the intestine.
5. Prevention of gallstines- Bile salts prevents the formation of gallstones by keeping the cholesterol into solution.

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