A2 Edexcel Food, Digestive System

Mucin:

a slimy protein substance which lubricates food making it easier to swallow.

Salivary Amylase:

An enzyme which initiates the break down of starch into maltose

Pepsin:

an enzyme which breaks down protein into smaller molecules called polypeptides

Hydrochloric Acid:

Activates pepsin and kills bacteria

Rennin:

an enzyme with coagulates milk protein. Important mainly in babies.

Enzymes in the pancreatic juice produced in the pancreas

Trypsin and Chymotrypsin:

Enzymes which continue the digestion of protein

Pancreatic Amylase:

An enzyme which breaks down starch into maltose. More effectiva than silavary amylase

Lipase:

An enzyme which hydrolyses lipids (fats and oils) into fatty acids and glycerol.

Enzyme in bile which is a yellow-brown fluid produced in the liver and stored in the gall bladder.

Peptidases:

Completes the breakdown of proteins by splitting polypeptides into the constituent amino acids.

Absorption

Nutrients are absorped from the stomach. Non fatty nutrients like monosacchrides, amino acids, water soluble vitamins and mineral salts are absorbed directly into the blood system.

Fatty Nutrients such as fatty acid and fat soluble vitamins pass into the lymph vessels and enter the blood stream at veins in the base of the neck

Carbohydrases break down carbohydrates

Lipases break down lipids (fats and oils)

Proteases break down proteins

Oxidases bring about oxidation reactions