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- Chewing is the cutting and mixing of food.To break down the food is a mechanical digestion from larger to smaller pieces.Chemical digestion in the mouth is minor but consists of salivary amylase
- Mouth
- The role of saliva - Saliva contains enzyme called salivary amylase. This enzyme is to breakdown the starch into maltose.Saliva also contains mucus which lubricates the food so it will be easier to swallow.Saliva contains hydrogen carbonate which provides optimum pH for amylase to digest the starch.
- OESOPHAGUSThe oesophagus takes food down to the stomach.The entrance to the stomach from the oesophagus is closed by a sphincter muscle.The muscle relaxes to let food pass into the stomach,then contracts to close the entrance again
- The stomach walls contain goblet cells which secrete mucus.It also contains other cells which produce enzymes and others which make hydrochloric acid.Then enzymes produced in the stomach digest proteins,so they are proteases.The hydrochloric acid produces a low pH in the stomach which kills harmful microorganisms in the food.The pH is also optimum pH for the protease enzymes that act in the stomach
- The mucus protects the walls of the stomach from gastric juices andprevents corrosion and ulcer.the pepsin is an enzyme to breakdown the proteins intopolypeptides.
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