Warm-Up 11/15/11B Day
1. What are the 6 nutrient groups?
2. What are the two types of proteins? How
are they similar? Different?
3. What level of body organization is the
digestive system?
4. You just ate a piece of pizza for lunch.
What organs does this pizza go through
once it enters your mouth?
Objective
• SWBAT take notes in order to list the 3
functions of the digestive system and
describe its organs.
• SWBAT analyze a cracker demo in order
to explain chemical and mechanical
digestion in the mouth.
Essential Question
• What functions are carried out in the
digestive system?
• Explain the roles of the mouth, esophagus,
and stomach in digestion.
Digestion Begins
3 important functions of the
digestive system:
1. Breaking down food into molecules the
body can use
2. Absorbing nutrients into blood
3. Eliminating wastes from the body
A closer look1. Breaking down food into molecules the
body can use
–
–
digestion =
process by which your body breaks down food
into small nutrient molecules
TWO kinds of digestion
1. mechanical digestion =
 foods are physically broken down
 Examples?
 Biting and chewing
TWO kinds of digestion
2. chemical digestion –
 chemicals produced by the body break
down the food into nutrients
 Example =
–
–
acid in your stomach breaks down food
starch in bread is broken down into individual
sugar molecules is another example
2nd Function of the digestive
system
2. Absorbing nutrients into blood –
 a.) after food is broken down into molecules
 b.) the nutrients must make their way into the
bloodstream
 c.) then the body can use them
*absorption =
 process by which nutrient molecules pass through
wall of the digestive system into blood
3rd Function of the digestive
system
3. Eliminate waste from the body

Everything in food that cannot be used
as nutrients is
eliminated from the body as wastes
- The Digestive Process Begins
Functions of the Digestive
System
• The digestive system
has three main
functions. First, it
breaks down food into
molecules the body can
use. Then, the
molecules are absorbed
into the blood and
carried throughout the
body. Finally, wastes
are eliminated from the
body.
Organs in digestive system…



1. mouth
2. esophagus
3. stomach
The Mouth


When your mouth waters, it prepares your
body for the food it is about to digest
Both mechanical and chemical digestion
begin in the mouth
- The Digestive Process Begins
The Mouth
• Both mechanical and chemical
digestion begin in the mouth.
Mechanical digestion in the Mouth





Your teeth are the first example of mechanical
digestion
Incisors, center teeth, cut the food into bite-sized
pieces.
Canines, sharp and pointy, tear food into smaller
pieces.
Molars- grind and crush food
Saliva moistens the pieces of food into one slippery
mass
- The Digestive Process Begins
The Mouth
• Both mechanical and chemical
digestion begin in the mouth.
Cracker demo
Procedure
1. Put a small piece of cracker in your mouth.
Do not chew it.
2. What do you taste? Record your
observations.
3.Let it dissolve in your saliva. Now what do
you taste? Record your observations.
4. What do you think happened? Why?

Chemical digestion in mouth


Why does the cracker taste sweet?
Saliva is an example of CHEMICAL digestion
–

Saliva has broken down the starch in the cracker
into a sugar molecule.
The chemical in saliva that digests starch is
an ENZYME.
- The Digestive Process Begins
The Mouth
• Both mechanical and chemical
digestion begin in the mouth.
Enzymes





Definition=
proteins that speed up chemical reactions in
your body.
Many are produced by your body
Each has a specific shape.
Its shape enables it to take part in only ONE
kind of chemical reaction.
- The Digestive Process Begins
The Mouth
• The shape of an enzyme molecule is
specific to the shape of the food molecule
it breaks down. Here an enzyme breaks
down a starch into sugars.
Independent Practice
1. In your own words, define and explain the three
functions of the digestive system.
2. What is digestion? Why is it a necessary
process?
3. What is absorption? Why is it a necessary
process?
4. Think about what you ate for breakfast today.
Describe what happened/will happen to the
food you ate in terms of the three functions of
the digestive system.
5. How is mechanical digestion different than
chemical digestion?
Exit Slip
• What functions are carried out in the
digestive system?
• Explain the roles of the mouth, esophagus,
and stomach in digestion.
Homework
• Draw and label the parts/organs of the
digestive system.
• Define key terms for section 3- on
flashcards.