Bile Concentration

One of the most important organic compounds is lipids. Lipids make up 18-25% of body mass in lean adults. Totora Grabowski ninth edition; Principles of anatomy and physiology, page 44. Lipids contain carbon, hydrogen and oxygen. Lipids are described as being hydrophobic molecules which also means they are non-polar and insoluble to water. Only smaller lipids (some fatty acids) are dissolved in the watery blood.

The digestion of Lipids

The digestion of lipids occurs mainly in the stomach. The digestive process is to break down substances such as lipids in order for it to be possible to be absorbed into the blood stream and distributed into body cells. Fats are digested and broken down into monoglycerides and fatty acids by the enzyme lipase. Bile is another substance that is involved in the digestion and absorbtion of lipids. What bile does is it emulsifies fats, this means it rearranges fat molecules into small droplets that are then suspended in the watery contents of the digestive tract. http://www.annecollins.com/digestive-system/digestion-of-fats.htm - accesed 13/03/2012 See fig 1a and 1b.

Fig 1a shows an annotated diagram of neural and hormonal stimuli that promote production and release of bile. Adapted from Totora Grabowski ninth edition; Principles of anatomy and physiology, page 846.

Production storage and biliary system. Fig 1b.

Fig 1b shows an annotated diagram of the Biliary system. Adapted from Human Body; An illustrated guide to every part of the human body and how it work, A Dorling Kindersley Book. Page 231.

The Biliary system

Bile is greenish/brown in colour and is a fluid. It is in some sense a waste product of the livers chemical processes, however, it plays a vital part in the digestion of fats. It travels from the liver either straight to the duodenum or to the gallbladder, where it is stored and concentrated. Once concentrated, the bile fluid is then transported down the common bile duct and into an expanded area called ampulla of vater (this is labelled in the diagram). This process occurs before entering the duodenum through an opening called the sphincter of Oddi. Human Body; An illustrated guide to every part of the human body and how it work, A Dorling Kindersley Book. Page 231.

Role and composition of Bile - Emulsification

Every day, hepatocytes secrete 800 - 1000ml of bile, a greenish/brown coloured fluid. Totora Grabowski ninth edition; Principles of anatomy and physiology, page 843. It is claimed to have a pH of 7.6 - 8.6 and consists mostly of water, bile salts, cholesterol, bile pigments and several ions. Bile is partly a digestive secretion.