Digestive
System III
Note Taking
Fill in Chart
Image source:
http://www.flickr.
com/photos/liujo
anne/2172007698
/
Is this in your notes yet?
Review 3 functions of digestive
system!
 1.
D
 2.
A
 3.
E
INTERCONNECTION
Digestion
Absorption
Elimination
of Waste
Digestion
breakdown of food  into
molecular components
small enough to cross the
plasma membrane
Inside the Human
Mouth
Photograph by Lennart Nilsson
Inside the mouth,
shown magnified here,
teeth, tongue, and
saliva work together to
physically and
chemically break
down food.
Humans produce up
to 3 pints (1.4 liters) of
saliva daily, and
chemical enzymes in
the saliva play a major
role in disintegrating
starchy foods.
http://science.nationalgeographic.com/science/photos/digesti
ve-system/?source=A-to-Z#/human-mouth_1002_600x450.jpg
NOTES!
We know that M and C digestion
begins in the mouth…
 What
are the structures in the mouth?
 What do they do?
 Which structure starts C digestion?
NOTES!
What’s happening with your
saliva?
 Starch
is a long glucose polymer
 Enzyme amylase, found in your saliva,
breaks down starch into smaller glucose
units
Take notes in your notebook!
Cracker Experiment
 Each
person gets one cracker.
 Break off a small part of your cracker and
place it on the front of your tongue. Leave it
there for at least two minutes!
 What does it taste like (bitter, sweet, salty)?
 What is happening and why?
 Is there a connection between this
experiment and the peristalsis experiment?
Brain Pop on the
Digestive System
http://www.brainpop.com/health/bodysystems/digestive
system/preview.weml
Describe peristalsis and why
you can eat upside down…
Turn and talk to your table partner
Mouth – Esophagus - ??
What comes Next?
NOTES!
Your stomach!





Muscular sac where food mixes with gastric
juice (also called stomach acid or
Hydrochloric acid (HCl)).
If HCl is so strong, why doesn’t your stomach
burn from the inside out?
HCl is produced in the stomach lining and
activates the enzyme pepsin which starts
protein digestion.
Does peristalsis occur in the stomach too?
Why or why not?
Discuss with the people at the table in front or
behind you.
NOTES!
The Small Intestine
 What
structures are associated with the
small intestine?




D
L
G
P
 What
functions of the digestive system do
they support?
This colored scanning
micrograph shows a cast
of blood vessels from the
external wall of the small
intestine.
Measuring about 22 feet
(6.7 meters) in length,
the small intestine
performs most of the
major digestion and
absorption of nutrients.
The walls of the small
intestine are lined with
millions of projections
called villi, which absorb
and transmit nutrients
into the bloodstream.
http://science.nationalgeographic.com/science/photos/digestivesystem/?source=A-to-Z#/small-intestine-vessels_1211_600x450.jpg
NOTES!
Villi in the small intestine
 Bumpy
so well suited
for absorption.
 Tiny finger shaped
structures increase
surface. They also
absorb nutrient
molecules and pass
them to the blood
vessels.
Villi Volunteers
(two different people!)





Compare the two different pieces of fabric.
The one with the finger like pieces is similar to
the villi.
Which fabric will absorb more water? What
do you think?
Each volunteer should submerge their piece
of fabric into the water and hold it for five
seconds.
Bring the fabric out of the water and squeeze
the water into a cylinder.
Which piece of fabric absorbed more water?
VILLI
Image source:
http://www.sciencephoto.com/media/310014/enlarge
How do nutrients get to the
rest of the body?
Nutrients
pass from the cells of
the villi into the body.
Blood vessels are covered by
a single layer of cells so
nutrients pass through cells
into the blood.
Absorption
passage of
molecules
into body's
interior &
passage
throughout
the body
Liver and Gall Bladder
Two more volunteers!





Fill two jars half full of
water. Add a few
drops of oil to each jar.
Add ¼ tsp baking soda
to one jar.
Stir contents of both
jars.
Which jar did the oil
begin to break up?
What does the baking
soda represent?
NOTES!
Small Intestine
Liver produces bile.
• Bile is a substance (not an enzyme) that breaks
up fat particles into fat droplets and neutralize
stomach acids .
Gall Bladder stores bile.
Pancreas produces enzymes to
chemically breakdown fat droplets.
NOTES!
Last but not least…
The Large Intestine
Colon
• Removes waste
and reabsorbs
water and salts
Rectum
• Stores waste.
Anus
• Excretes waste.
Use your notes to help you fill
in your chart!