Transcript Slide 1
The Digestive System
and Nutrition
7th Grade Science
Mrs. Christopherson
Mrs. Goede
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 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