What is the function of bile in the small intestine?
Bile is produced by the liver and stored in the gall bladder to be squirted along the bile duct into the duodenum as food leaves the stomach.
Along with the pancreatic juice this neutralises the acidic contents of the stomach as they enter.
Bile also helps emulsify fats in foods by causing the fats to mix in and allowing the digestive enzyme lipase to digest the fats.
What is the pancreatic juice?
Pancreatic juice is added to the food as it enters the duodenum.
It contains enzyme to digest carboydrates, proteins and lipids.
Along with bile it neutralises the acidic content of food coming from the stomach.
What is thw pH of the small intestine?
Slightly alkali at 7.4.
How does food enter the duodenum?
Via the pyloric sphincter muscle.
Why would fats not mix with digestive juices without the help of bile and lipase?
Because digestive juices are all water based.
Bile causes the fats to mix in and allows the digestive enzyme lipase to digest the fats.
What is the ileum?
As food moves along the duodenum it is broken down into soluble units that can be absorbed along the ileum of the small intestine.
The ileum's function is the absorb digested food materials.
The ileum lining is long and has a large surface area so it can absorb food quickly and efficiciently.
The surface area is increased due to the folds in the lining of the small intestine and tiny finger like projections on the ileum known as villi (sing. villus)
What is the villi?
Singular - villus.
Villi are tiny finger like projections on the surface of the ileum.
There are millions, with each containing hundreds of micro-villi.
Within each villus is a network of blood capillaries and a lacteal (part of the lymphatic system).
Describe the process of absorption and digestion in the small instestine, and "assimilation"..
Most of the digested food is absorbed into the blood capillaries but digested fats are absorbed into the lacteal vessels.
The blood capillaries of the villus join the hepatic portal vein to transport the digested food to the liver, which acts as a food processing plant.
The digested food is distributed to the various parts of the body by the blood circulatory system and the soluble food particles are absorbed into the body cells to build new cells.
This process is known as "assimilation".