Transcript Final Digestion and Absorption Chapter 15 Section 3 Key Concepts   What digestive processes occur in the small intestine, and how are other digestive organs involved? What role does the.

Final Digestion and
Absorption
Chapter 15
Section 3
Key Concepts

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What digestive processes occur
in the small intestine, and how
are other digestive organs
involved?
What role does the large
intestine play in digestion?
Key Terms
Small intestine
Liver
Bile
Gallbladder
Pancreas
Villus
Large intestine
Rectum
Anus
The stomach
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The stomach can be thought of as
the “ticket taker” of the digestive
system.
Once the food has been changed
into a thick liquid, the stomach
releases a little of the liquid into the
next part of the digestive system.
The slow smooth passage of liquid
ensures digestion and absorption
can take place efficiently
Small Intestine
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After the liquid leaves the stomach it
enters the small intestine
It is 6 meters long, and makes up
two thirds of the length of the
digestive system
It is approx. 2-3 centimeters wide
Mechanical digestion is complete
and chemical digestion has just
begun
(2)
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Starches and proteins have been
partially broken down
Fats haven’t yet been digested at all
Almost all chemical digestion and
absorption of nutrients takes place in
the small intestine
As it moves into the small intestine it
mixes with enzymes and secretions
that are produced by the small
intestine, the liver and the pancreas
Small tubes deliver this substance
Liver
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Largest organ in the body
Breaks down such things as medicine’s
and helps eliminate nitrogen from the body
Produces bile
Bile physically breaks up large fat particles
into smaller fat droplets

Ex. Soap breaks up grease into small droplets
that can mix with soapy water and be washed
away. Bile mixes with the fats in food to form
small droplets. Droplets can then be chemically
broken down by enzymes produced in the
pancreas.
Pancreas
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Produces enzymes that flow into
the small intestine and help
break down starches, proteins
and fats
Digestive enzymes do not break
down all food substances

Ex -fiber in food isn’t broken down
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Instead fiber thickens the liquid
material in the intestine making it
easier for peristalsis to take place
Absorption in the small
intestine
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After chemical digestion, small
nutrient molecules are ready to
be absorbed by the body
The inner surface or lining of the
small intestine looks bumpy-villi
(tiny finger shaped structures)
cover the surface
Villi absorb nutrient molecules
(2)
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Tiny blood vessels run through the center
of each villus
Nutrient molecules pass from cells on the
surface of a villus into blood vessels
Blood carries the nutrients throughout the
body for use by body cells
If all the villi were laid out the total surface
area of the small intestine would be about
as large as a tennis court
The increased surface enables digested
food to be absorbed much faster than if the
walls of the small intestine were smooth
Large intestine
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1.4 meters long-average size of a
bathtub
Runs up the right-hand side of the
abdomen, across the upper
abdomen and then down the left
hand side
Contains bacteria that feed on the
material passing through-they are
helpful bacteria they make certain
vitamins-ex vitamin K
(2)
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Large intestine contains water and
undigested food
As the material moves through the large
intestine water is absorbed into the
bloodstream
Remaining material is reading for
elimination from the body
Large intestine ends in the rectum
Waste material is compressed into a solid
form
The waste material is eliminated from the
body through the anus at the end of rectum
1. What are the functions of
the small intestine?
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Absorption
Most chemical digestion takes
place here
2.Do foods pass through the
liver and pancreas?
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no
3. What is their role in
digestion?
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The liver produces bile that
breaks up fat particles
Pancreas produces enzymes
that help break down starches,
proteins and fats
4. What is the advantage of a
long small intestine?
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The length provides more
surface on which nutrients are
digested and absorbed.
5. What structures are inside the
single villus in the diagram?
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Blood vessels run through it
6. How do nutrients from the
small intestine get to the rest
of the body?
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They pass from the cells on the
villi into blood vessels
7. What two digestive
processes occur in the small
intestine?
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Chemical digestion
absorption
8. Which key nutrient is
absorbed in the large intestine
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water
9. What happens as food
moves through the large
intestine
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Water is absorbed into the
bloodstream and the remaining
material is readied for
elimination from the body