Animal organisation - digestion - AQAThe liver and digestion
The major nutrients required for a healthy diet are carbohydrates, proteins and lipids. The digestive system breaks down large molecules of food, which are then absorbed into the bloodstream.
The liverThe large organ, beside the stomach, which has many functions, including processing substances absorbed by the digestive system and a role in the storage of the body's carbohydrate. does not secrete any enzymeA protein which catalyses or speeds up a chemical reaction., but it plays an important role in digestionThe breakdown of large insoluble food molecules to smaller soluble ones., and then processing food moleculeA collection of two or more atoms held together by chemical bonds. that have been absorbedWhen a substance is taken in by something or moved across a barrier such as a cell membrane, it is said to have been absorbed..
The liver produces bileA substance produced in the liver. It emulsifies fats to prepare them for digestion..
Bile:
emulsifyTo mix water with fats and oils to produce a cloudy mixture called an emulsion.lipidFat or oils, composed of fatty acids and glycerol., breaking them up physically into tiny droplets. Tiny droplets have a much larger surface area, over which lipases can work, than larger pieces, or drops of lipid.
Contains sodium hydrogencarbonate, which is an alkaliA base which is soluble in water.. It neutralises stomach acid and produces the optimumThe best or most appropriate - for instance, the conditions under which an enzyme works best (eg temperature and pH).pHScale of acidity or alkalinity. A pH (power of hydrogen) value below 7 is acidic, a pH value above 7 is alkaline. for pancreasLarge gland located in the abdomen near the stomach which produces digestive enzymes and the hormone insulin. enzymes.
Is produced in the liver, but stored and concentrated in the gall bladderStores bile before releasing it into the duodenum..