Digestive
System
Organs of the Digestive System
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mouth
esophagus
stomach
small intestine
large intestine
rectum
anus
pancreas
gall bladder
liver
Functions of the Digestive
System
• Your cells need a lot of energy. They
get energy from the food we eat.
• But, your digestive system has to break
down the food we eat into microscopic
nutrients before our cells can use it.
Functions of the Digestive
System
• Digests food into molecules the body
can use (physical or chemical change).
• Absorbs nutrient molecules and carries
them around the body (physical
change).
• Eliminates waste material from unused
nutrients.
mechanical digestion
vocabulary
word!
• mechanical digestion - food is
physically broken down into smaller
pieces by breaking, crushing and
mashing.
• increases the surface area of the food
• begins in the mouth
– teeth chewing/tearing
– movement of smooth muscles
chemical digestion
vocabulary
word!
• chemical digestion - chemicals
(enzymes)produced by the body break
foods into their smaller nutrients.
– mouth
– stomach
absorption
vocabulary
word!
• absorption - process by which nutrient
molecules pass through the wall of
your digestive system into your blood.
– The lining of the small intestine is covered
in villi that aid in absorption
vocabulary
word!
elimination
• elimination – removal of waste material
left over after food is digested to
prevent illness.
mouth
• Digestion begins in the mouth
– mechanical – teeth
– chemical - saliva
vocabulary
word!
salivary gland
• salivary gland – gland that produces
enzymes that help to break down food
chemically.
vocabulary
word!
esophagus
• esophagus - muscular tube that
connects your mouth to your stomach.
– moves food down into your stomach
using involuntary muscle contractions
(peristalsis).
– Lined with mucus that allows food
to slide down.
vocabulary
word!
stomach
• stomach – a muscular bag that crushed
food and contains acids and enzymes
for breaking down food.
• Most mechanical digestion takes place
in the stomach because it is made of
thick smooth muscle.
• Chemical digestions also takes place
• Mucus keeps the acids from burning a
hole in your stomach.
Stomach
vocabulary
word!
small intestine
• small intestine – muscular tube where
most of the chemical digestion takes
place and most nutrients are absorbed.
• Covered in villi which
enlarge the surface area
small intestine
The villi increase the
surface area that can
absorb nutrients.
vocabulary
word!
liver
• liver – large organ that produces bile
and breaks down medicines and other
chemicals.
• The gall bladder
stores bile
vocabulary
word!
pancreas
• pancreas - secretes insulin to carry
glucose around the body and makes
enzymes that help digest food.
• Causes diabetes when it does not make
insulin.
large intestine
vocabulary
word!
• large intestine – muscular tube where
vitamins B and K are made and water is
removed from food waste.
• Food spends 18-24 hours here
rectum and anus
• rectum – end of the large intestine,
forms the solid waste
– elimination
• anus – muscular opening at the end of
the rectum
– elimination
The digestive system interacts
with:
• muscular system (smooth
muscle) to move and digest food.
• respiratory system to provide
oxygen.
• circulatory system to move
nutrients.
Which cell parts are like the
digestive system?
Which one makes energy?
mitochondria
Which one allows materials to pass in and out?
cell membrane
Which one helps get rid of waste?
lysosomes