Download Mechanical Digestion

The Digestive System
and Nutrition
7th Grade Health
Important Vocabulary

Digestion: The process of breaking food
down to be used by the body.
 Why
is digestion important?
Food must be broken down in order for our body to
be able to absorb all of the substances important
for daily functions.
 Food must be small enough to be absorbed into
the blood and carried to the cells.

Important Vocabulary

Digestion cont:
 Two
types of digestion:
Mechanical Digestion: occurs in the mouth
(chewing), and in the stomach (churning of
stomach muscles)
 Chemical Digestion: occurs through the use of
enzymes (substances which chemically act on
food to break it down) in saliva, the stomach, in the
small intestine

Important Vocabulary: Organs of
the Digestive System

Mouth: The first step in digestion is
actually getting the food into your body.
 Teeth:
mechanically break food down into
smaller pieces
 Saliva: softens food and chemically breaks
food down further
 Tongue: moves food around the mouth, forms
a bolus (ball of food)
Important Vocabulary: Organs of
the Digestive System

Esophagus: a hollow tube at the back of
the throat that connects to the stomach.
To prevent food from “going down the wrong
pipe” a flap of skin called the epiglottis closes
over the opening of the trachea (windpipe)
when we swallow
 Peristalsis: muscular contractions that move
food down the esophagus into the stomach.


Imagine squeezing a tube of toothpaste…
Important Vocabulary: Organs of
the Digestive System

Stomach: a hollow, J-shaped organ
located below the esophagus and above
the small intestine.
 The
stomach uses both mechanical and
chemical digestion to break food particles
down.
Mechanical digestion: 3 layers of muscles
 Chemical digestion: digestive or gastric enzymes

Important Vocabulary: Organs of
the Digestive System

Small Intestine: responsible for absorbing
nutrients from food.
 First
1/3 of the S.I. :Bile from the gall bladder
and digestive enzymes from the pancreas and
walls of the small intestine further break food
down.
 Second 1/3 of the S.I.: contains finger-like
projections called villi
Important Vocabulary: Organs of
the Digestive System

Small Intestine cont:
 Villi:
increase the surface area of the S.I. so
that more nutrients can be absorbed into the
blood stream
Important Vocabulary: Organs of
the Digestive System

Large intestine: “large” because it is wider
in diameter than the small intestine (about
3” vs. 1”). Responsible for absorbing water
from undigested food.
 Material
found in the large intestine is mostly
food that cannot be digested any further and
water.
Important Vocabulary: Organs of
the Digestive System

Large Intestine: 3 parts
 Colon:
Absorbs water and nutrients from food,
as the material moves through the colon it
gets harder and harder-turning into feces.
 Rectum: Stores feces. Feces move to the
anus by peristalsis.
 Anus: Eliminates solid waste from the body
Other Organs

Liver: produces bile, is located to the right
of the stomach.
 Bile:

responsible for breaking down fats
Pancreas: located behind the stomach,
and above the small intestine.
 Secretes

digestive enzymes
Gall Bladder: stores and excretes bile
Some videos to use
http://www.youtube.com/watch?v=Z7xKY
Nz9AS0
 http://kidshealth.org/kid/htbw/_bfs_DSmov
iesource.html
 http://www.youtube.com/watch?v=q3986Y
fl5cU
 http://kitses.com/animation/swfs/digestion.
swf

http://kitses.com/animation/swfs/di
gestion.swf
http://kitses.com/animation/swfs/di
gestion.swf
http://kitses.com/animation/swfs/di
gestion.swf
http://kitses.com/animation/swfs/di
gestion.swf
http://kitses.com/animation/swfs/di
gestion.swf
http://kitses.com/animation/swfs/di
gestion.swf
http://kitses.com/animation/swfs/di
gestion.swf