Digestion

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Digestion

• IB Biology
• Study guideP47
• Course companionp203

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The human digestive system
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Digestion

• Reason
• 1.filtrate the unsuitable food.
• 2.Break the large molecules,make them easy to
  absorb.
• What to digest1.starch 2.protein
  3.triglycerides(fats and oils)

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Digestion

• Enzymes are essential to speed up the digestion.
• example

amylase protease lipase
enzyme salivary amylase pepsin pancreatic lipase
source salivary glands wall of stomach pancreas
substrate starch proteins triglycerides
products maltose small polypeptides fatty acid and glycerol
optimum PH 7 1.5 7
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Absorption and Assimilated

• The process that makes food into body's
  tissues.--Absorption
• Happen in small intestine.
• Villi in small intestine absorb food molecules
• After food has been absorbed we call it----
  assimilated.

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villus
1.Villi increase the surface area over which food
is absorbed. 2. food passed epithelium to be
absorb 3.Capillaries inside the villus are close
to the epithelium so the distance for diffution
of foods is very small. 4Lacetal is the center
branch,it carries away fats.
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Function of the stomach and the intestines

• The baleful bacterias will be killed in the
  stomach by the acid conditions.
• The indigestible parts of the food with water
  will pass through the large intestine and
  egested from the anus.

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Vocabulary

• Absorption--The process that makes food into
  body's tissues.
• Assimilated--After food has been absorbed .
• Triglycerides(fat and oil)
• villus--On the wall of the small intestine.

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End