Transcript THE HUMAN DIGESTIVE SYSTEM.

THE HUMAN
DIGESTIVE
SYSTEM
The journey of food
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OB6
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identify and locate the major parts of the
digestive system including the mouth,
oesophagus, stomach,liver, pancreas,
small intestine and large intestine, and
know their functions
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The Mouth.
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Teeth break down food
into small pieces.
Salivary glands make
saliva.
Chewed food gets mixed
with saliva.
Saliva contains enzymes,
which start to digest
starch to sugar.
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The Oesophagus.
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Passes food down to
your stomach.
The oesophagus has
circular muscles in its
wall.
These muscles
contract and squeeze
in behind the food to
push it along.
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The Stomach
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Muscular bag that holds
2 litres of food.
Secretes hydrochloric
acid.
Makes digestive juices.
Muscular walls churn
the food making sure
it’s all mixed.
After 2-3 hours
churning it’s a runny
liquid.
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The Small Intestine
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Actually 6 m long!
Plays important roles in
digestion and absorption
Two important liquids
are added here:
Pancreatic juices
Bile
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Absorption
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Digested food has to pass into the blood
through the gut wall.
Well designed – thin lining, good blood supply
and a VERY LARGE surface area.
It has a folded inner lining, millions of tiny
villi
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Pancreas
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Produces digestive
enzymes
E.g. amylase
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Liver
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After food has been
absorbed into the blood,
the food is taken to the
liver.
The liver processes
some of it, before it
goes any further.
The food dissolved in
plasma is the taken to
other parts of the body.
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The Large Intestine.
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Mainly fibre, dead cell,
bacteria and water
reach here!
As it moves along here
most of the water is
absorbed into the blood.
Faeces are stored in the
rectum.
Eventually egested out
of the anus, roughly 24
–48 hours after eating.
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