The break down of large, insoluable molecules into small, soluable food molecules so that they can be absorbed into the bloodstream.
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What are the large, insoluable molecules?
Protein, carbohydrates and fat.
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How is protein broken down?
Protein is broken down by protease to form amino acids.
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How is carbohydrate broken down?
Carbohydrate is broken down by amylast to form glucose.
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How is fat broken down?
Fat is broken down by lipase to form glycerol and fatty acids.
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How do we test for starch in food?
Use iodine. If starch is present, iodine turns from brown/orange to black/blue.
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How do we test for glucose in food?
Use Benedict's solution.If glucose is present, solution turns from blue to brick red when heated.
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How do we test for protein?
Use Biuret reagent. If protein is present, solution turns from blue to purple.
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What happens in the mouth?
Mechanical digestion (chewing), food gets mixed up with saliva. Saliva is produced by salivary glands, contains amylase for the chemical digestion of starch. pH is neutral.
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What is the oesophagus?
A tube connecting the mouth to the stomach. No digestion happens here.
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What is the stomach?
contains stomach acid (HCl) with a pH of 2. Also contains protease. There is also mechanical digestion in the stomach, it churns and mixes food.
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What happens in the small intestine?
The pH in the small intestine is neutral. This happens using bile from the liver. Bile also emusifies fat. This increases surface area for fat digestion. The pancreas releases enzymes into the small untestine and digestion finishes here.
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Where are digested food molecules absorbed?
In the small intestine.
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What is the large intestine?
This is where water is reabsorbed.
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What is the rectum?
Stores faeces.
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How is food moved through the digestive system?
By a procen called peristalsis.
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What is faeces?
Bacteria, cells from the digestive system and food material that cannot be digested, e.g. fibre.
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