Digestive System

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Digestive System
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Digestive System

• The digestive system can be divided into two
  parts
• Alimentary canal open ended muscular tube that
  forms a digestive tract between the mouth and the
  anus of an organism
• Accessory organs organs which produce
  secretions that assist in the digestive of food
  food does not pass through these organs

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Digestive System
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Steps in the Digestive Process

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• INGESTION
• The process of taking food into the body by the
  mouth
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•  
• DIGESTION
• The process of breaking food down into smaller
  components
• Two types of digestion
• a) Mechanical Digestion b) Chemical Digestion
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•  

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Steps in the Digestive Process

• ABSORPTION
• Involves broken down food particles leaving the
  digestive tract and moving to the blood transport
  system
• 80 of absorption occurs in the small intestine
• 20 of absorption occurs in the stomach and large
  intestine
• EGESTION
• Removal of solid waste (materials not absorbed by
  the body)

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Mechanical vs. Chemical Digestion

• Mechanical Digestion
• Physical breakdown of food into smaller parts (no
  chemical change)
• Involves primarily the MOUTH (biting, tearing,
  grinding, chewing) and STOMACH (muscular
  churning)

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Mechanical vs. Chemical Digestion

• Chemical Digestion
• Chemical breakdown of food into particles so
  small that they are able to be absorbed into the
  bloodstream and into the cells of the body.
• The chemical breakdown of food involves ENZYMES
  and DIGESTIVE JUICES.
• Enzyme protein that speeds up the rate of a
  biological reaction without being used up in the
  reaction

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Major Parts of the Digestive System

• Mouth
• Aids in mechanical breakdown
• Releases enzymes for chemical digestion
• Releases saliva to soften food
• Easier to pass into esophagus

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Major Parts of the Digestive System

• Esophagus
• Muscular tube connecting mouth to stomach
• Contains smooth muscle tissue
• Allows esophagus to relax and contract
• Contractions allow food to move along ?
  peristalsis

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Major Parts of the Digestive System

• The Stomach
• Main function ? to hold and churn food
• Stomach lining secretes digestive enzymes and
  acids
• Smooth muscle ? allows stomach to contract to mix
  stomach contents

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Major Parts of the Digestive System

• The Intestine
• Between stomach and anus
• Has cells that secrete mucus ? helps lubricate
  food
• Has lots of blood vessels interlaced through it
• allows nutrients to be absorbed into the blood
  from the digesting food

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Major Parts of the Digestive System

• The Intestine
• Small Intestine
• Approx 6 m long and narrow
• Most absorbing of food nutrients occurs here
• Large Intestine
• A.k.a. Colon
• 1.5 m long but bigger in diameter
• Most absorbing of water occurs here
• Remaining solid matter excreted as feces

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Accessory Organs

• Liver
• Produces bile ? helps with digesting food
• Detoxifies substances in the body
• Pancreas
• Releases enzymes
• Important hormone released ? insulin
• Allows our cells to use the sugars we ingest
• Gallbladder
• Stores and releases acids to help in the
  digestion of food

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Accessory Organs
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Homework

• Booklet Questions 1-6
• Answer 2 -5 on page 82
• Additional Question
• Describe what heart burn is. (Hint you can
  find the info on page 81)
• Study for circulatory and respiratory systems quiz