Function of Bile
- Bile is an alkaline substance produced by cells in the liver
- Before being released into the small intestine, bile is stored in the gall bladder
- Bile travels from the liver and gall bladder to the small intestine via a small tube called the bile duct
Organs that are involved in bile production and secretion diagram
Bile is produced in the liver and stored in the gall bladder
- Bile has two main roles:
- Neutralising the hydrochloric acid from the stomach
- The alkaline properties of bile allow for this to occur
- This neutralisation is essential as enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach
- Breaking apart large drops of fat into smaller ones (and so increasing their surface area)
- This is known as emulsification
- Neutralising the hydrochloric acid from the stomach
- The more alkaline conditions and larger surface area allows the lipase enzymes to chemically break down the fat (lipid) molecules into glycerol and fatty acids at a faster rate
The process of emulsification diagram
Bile breaks large fat droplets into smaller ones with a larger surface area
Examiner Tip
Emulsification is the equivalent of tearing a large piece of paper into smaller pieces of paper. This is an example of mechanical digestion, not chemical digestion – breaking something into smaller pieces does not break bonds or change the chemical structure of the molecules which make it up, which is the definition of chemical digestion.
