Transcript Chapter ---- Carbohydrates: Sugar, Starches and Fiber

Chapter 3
Digestion, Absorption,
and Metabolism
Digestion and Absorption
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Biochemically, “you are what you eat” is
true!
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Food and fluid taken into the body is broken
down into smaller components so it can be
used by the body.
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The digestive tract begins at the _________ and ends at the _______.
esophagus; small intestine
a.
b.
mouth; pancreas
esophageal sphincter; stomach
c.
d.
mouth; anus
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Overview of the Digestive System
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Digestion and
Absorption

The brain is
involved in
digestion and
absorption.
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Digestion and Absorption

Pharynx and Epiglottis
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Digestion and Absorption
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The mouth is the entry point for food into the
digestive tract.
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Saliva contains salivary amylase, which helps to
break down carbohydrates and lysozymes, which
help to inhibit bacterial growth in the mouth.
Chewing mechanically breaks food down,
increasing the surface area in contact with
digestive enzymes.
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Chewing is an important digestive function because it
improves the functionality of
a.
b.
c.
d.
enzymes.
hormones.
mucus.
peristalsis.
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Digestion and Absorption
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Esophagus
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Overview of the Digestive System
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Digestion: process of breaking food into
components small enough to be absorbed by
the body
Absorption: process of taking substances into
the interior of the body
Gastrointestinal tract: hollow tube consisting of
the mouth, pharynx, esophagus, stomach,
small intestine, large intestine and anus
Transit time: amount of time it takes food to
pass the length of the GI tract
Feces: body waste, including unabsorbed food
residue, bacteria and dead cells
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Digestion and Absorption
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Stomach
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Digestive Secretions
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Digestion inside the GI tract is assisted by
digestive secretions.
Mucus: viscous material produced by goblet
cells; mucus moistens, lubricates and
protects the GI tract
Enzymes: protein molecules that speed up
chemical reactions; enzymes are not
changed during reactions
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Digestive Enzymes
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Digestive Hormones
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Food moves through the digestive
tract by wavelike contractions
called
a)
quickening.
b)
the Heimlich maneuver.
c)
peristalsis.
d)
segmentation.
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Digestion and Absorption
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Digestion and
Absorption

The
gallbladder,
liver and
pancreas
are involved
in digestion
and
absorption.
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Which of the following
accessory organs releases its
secretions into the GI tract?
Gallbladder
Pancreas
Salivary glands
All answer choices
are correct
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Structure of the Gut Wall
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GI Tract’s Role in Immune Function
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
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The GI tract plays an important role in
protecting the body from infection.
The GI tract limits the absorption of toxins
and disease-causing organisms.
Some cells of the immune system are
present in the GI tract:
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Phagocytes
Lymphocytes
Antibodies
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Digestion and Absorption
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The large intestine does not participate in
digestion.
The large intestine can absorb water and
some vitamins and minerals.
The large intestine contains the colon and
the rectum.
Water, nutrients and fecal material may
spend up to 24 hours in the large intestine.
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The primary site of nutrient absorption is the
a)
liver.
b)
large intestine.
c)
stomach.
d)
small intestine.
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Absorption
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Digestion and Absorption of a Meal
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Transport of
Nutrients
Around the
Body: The
Cardiovascular
System
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Transport of Nutrients Around the
Body: The Hepatic Portal Circulation
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Metabolism of Nutrients
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Metabolic pathways are a series of reactions
needed to transform food into a final product
that can be used by the body.
Catabolic pathways release energy trapped
in chemical bonds.
Energy from catabolic reactions is converted
into ATP.
ATP is the energy currency of the cell.
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ATP
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Metabolizing Nutrients:
Cellular Respiration
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Elimination
of Metabolic
Wastes:
Body Organ
System
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Elimination of Metabolic Wastes:
The Kidneys
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The two major functions associated with the
digestive system include digestion and
metabolism.
absorption.
circulation of nutrients in the
blood.
excretion of metabolic waste
products.
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