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Human Nutrition
Biological Molecules:
Carbohydrates:



Carbohydrate molecules contain the elements carbon, hydrogen and oxygen
...


Proteins:



Made up of long chains of amino acids
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Lipids:



Built from fatty acids and glycerol
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Test for Glucose:




Add Benedict’s reagent to a sample and heat it
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If it is
positive it will form a coloured precipitate
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The higher the concentration of glucose, the further the colour change goes
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If present, substance changes from brown-orange to blue-black,

A Balanced Diet:

Enzymes and Digestion:

Bile:
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

Produce in the liver
...

The hydrochloric acid in the stomach makes the pH too acidic for enzymes in the
small intestine to work properly
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Bile also emulsifies fat
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This gives a much bigger
surface area of fat for the enzyme lipase to work on – digestion happens faster
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Teeth break down food mechanically
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Liver:


Where bile is produced
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It produces the protease enzyme, pepsin
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Pancreas:
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Produces protease, amylase and lipase enzymes
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Gall Bladder:
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Where bile is stored
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Small Intestine:



Produces protease, amylase and lipase enzymes to complete digestion
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Anus:
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Where faeces leaves the body
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Its job is to squeeze boluses (balls of food) through the canal
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The Digestive Process:
Ingestion:


Putting food in you mouth
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There are two types:
o Mechanical – Teeth and stomach muscles
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Absorption:



The process of moving molecules through the walls of the intestines into the blood
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Assimilation:
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

When digested molecules have been absorbed, they’re moved into body cells
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This is known as assimilation
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Egestion:


All of the undigested stuff forms faeces
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This is
egestion
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It’s very long, so there’s time to break down
and absorb all the food before it reaches the
end
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Each cell on the surface of a villus also has its own microvilli
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