The Digestive System

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The Digestive System
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mouth
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The Digestive System

• Ingestion
• ? food is taken into the body through the mouth
• 2) Digestion
• ? food is broken down (physically and
  chemically)
• 3) Absorption
• ? nutrients are moved into the blood
• 4) Elimination
• ? solid waste passes from the digestive system
• out of the body

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Why is Digestion Important ?
When we consume food, the body needs to break
down the food into smaller molecules of
nutrients for the system to absorb the nutrients
into the blood stream
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How does the digestive system work ?
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Mechanical vs. Chemical Digestion
Mechanical Digestion ? begins in your mouth as
your teeth tear and grind food into
small pieces ? continues in the esophagus,
stomach, and small intestine by
pushing food along, churning and breaking it
into smaller particles.
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Mechanical vs. Chemical Digestion
Chemical Digestion ? process where acids,
bases and enzymes released into the
digestive track respond to semi-solid food
lumps and break it down
further ? for example in the stomach enzymes,
hydrochloric acid
(HCl), and mucus help the
body extract
nutrients from food
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What are the roles of the other organs? LIVER
? the liver produces bile, a substance that helps
to break down fats ? nutrients arriving from the
small intestine into the liver are made into
products that can be more easily used by the
body ? toxins are generally broken down into less
toxic substances ? the liver is the body's
'detoxifier'.
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What are the roles of the other organs? GALL
BLADDER ? bile produced in the liver is
transferred to the gallbladder where it is
stored until needed for digestion of fats
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What are the roles of the other organs? PANCREAS
? releases powerful digestive enzymes required
for chemical digestion when food reaches
the lower stomach ? also secretes another
substance to help neutralize stomach acid ? the
hormone insulin is made by the pancreas ?
insulin helps to balance blood sugar levels in
the body
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Did you know?
?It takes one to two days for food to pass
through the entire digestive system ?The
small intestine is about 20 feet long when laid
out flat ? When you smell food signals are sent
to your brain. Your brain shoots out
impulses that ? make your mouth water ? make
your stomach contract (hunger) ? make the
intestines start leaking
digestive chemicals ? The liver is the
only organ in the body that is capable of
regenerating if parts of it are removed (eg.
surgery) or become diseased

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Peristalsis

• peristalsis is wave-like
• movements of muscles
• peristalsis starts in the
• esophagus and continues
• along the entire digestive
• Path
• peristalsis works in one direction
• only
• reverse peristalsis occurs when
• we vomit

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