Download The Digestive System

From Food to Nutrients

The function of the digestive system is to
break down food into small molecules which
can diffuse into the blood stream where they
can be delivered to all cells of the body to use
for energy, cell activities, cell parts, making
enzymes, growth, repair, and body defenses.
The Digestive Tube:
Accessory Organs
Food actually passes
through these organs:
1. Mouth
2. Pharynx
3. Esophagus
4. Stomach
5. Small Intestine
6. Large Intestine
7. Rectum
8. Anus
These organs produce
chemicals that help with
digestion:
1. Salivary Glands
2. Liver
3. Gall Bladder
4. Pancreas
Physical Digestion:

Food is broken into
smaller PIECES
Chemical Digestion:
Food is broken into
smaller molecules.

Teeth break food into smaller pieces

Saliva is secreted into the mouth from the
salivary glands to help lubricate the food

Tongue forms a bolus (ball) of food that can
be swallowed easily

Amylase begins some
digestion of starch

Part of both digestive and respiratory system

When swallowing, a small flap called the
epiglottis blocks the opening of your
windpipe

Allows food to go down the esophagus

“Down the wrong tube”

10 inch long, muscular tube

Transports food from mouth to stomach

Food doesn’t just slide down, muscles
contract to push the food
down – peristalsis

2-3 seconds to go down

Stretchy, J-shaped sac

Stomach is like a blender
Slowly grinds food into mush
called chyme

Pepsin (proteinase) breaks
down proteins into amino acids
Acids denature bacteria

1 inch in diameter, 21 ft long (stretched out)

Food spends about 4 hours in the S.I.
Bile (from liver) breaks fats into smaller pieces.
 Bicarbonate (from pancreas)
neutralizes stomach acid.

Lipases, starchases, and
proteinases from small intestine
and pancreas digest food.

By now, the food is
digested into small and
medium molecules.

LOTS of thin finger shaped
projections called villi line
the small intestine.

Nutrients diffuse through
the villi into the blood stream
and travel to your cells.



Tiny tube with closed end coming off the L.I.

Contains some white blood cells to fight
disease.

Holds bacteria
to digest cellulose.

2-3 inches thick

5-6 feet long


Undigested food and
water passes through
Absorbs water as waste
passes through forming
feces (solid waste)
Rectum

5 inch, muscular sac

Waste is solidified

Storage for feces.
Anus

Ring shaped muscle

Releases feces
Liver is the largest organ – small football

Produces bile which changes large fat drops into
smaller droplets.
Gallbladder – small 1 inch sac behind liver

Stores bile from liver

Bile secreted into the
small intestine as needed
6 inches long – spongy – behind stomach
 Secretes:
1) Bicarbonate to neutralize stomach acid
2) Proteinase to digest protein
3) Starchase to digest starches
4) Lipase to digest fats


The digestive system
is very important
because without it,
your body couldn’t
get the nutrients it
needs in order to
grow big and strong!