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Chapter 18
DIGESTIVE SYSTEM
LINING OF THE
DIGESTIVE SYSTEM
• Peritoneum - two-layered membrane
– Mesentery - part that attaches to
posterior wall of abdominal cavity
– Greater omentum - anterior portion
that protects abdominal organs
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FUNCTIONS OF THE
DIGESTIVE SYSTEM
• Break food into smaller pieces
• Change food chemically into fat,
carbohydrates, and protein
• Absorb nutrients into blood
capillaries of small intestines
• Eliminate waste products of
digestion
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ORGANS OF DIGESTION
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ORGANS OF DIGESTION
• Many organs contribute to
digestion
– Mouth
– Tongue
– Salivary glands
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ORGANS OF DIGESTION
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TEETH/ ACCESSORY ORGAN
OF DIGESTION
• Structure of a tooth
– Crown
– Neck
– Root
– Periodontal membrane
– Pulp cavity
– Dentin
– Enamel
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ESOPHAGUS
• The esophagus is a muscular tube
beginning at the lower end of the
pharynx, passing through the
diaphragm and connecting to the
upper portion of the stomach
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STOMACH
• Stomach is divided into 3 portions
– Fundus - upper part
– Greater curvature (body) - middle
– Pylorus - lower portion
• Gastric juices are secreted by
millions of gastric glands
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SMALL INTESTINE
• The final preparation of food to be
absorbed occurs in the small
intestine
• Divided into three sections
– Duodenum
– Jejunum
– Ileum
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SMALL INTESTINE
• Digestive juices
– Enzymes, secretin, cholecystokinin
stimulate digestive juices
– Pancreatic juices break down food
– Bile emulsifies fat
– Intestinal juices break food down
further for absorption
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SMALL INTESTINE
• Absorption in the small intestine is
accomplished through millions of
villi.
• The indigestible portion is passed
through to the large intestine
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LIVER/ACCESSORY ORGAN
OF DIGESTION
• Functions of the liver
– Manufactures bile which is necessary
for fat digestion
– Produces and stores glucose in the
form of glucogen
– Detoxifies alcohol, drugs and other
harmful substances
– Manufactures blood proteins
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
LIVER/ACCESSORY ORGAN
OF DIGESTION
• Prepares urea, the chief waste
product of protein metabolism
• Stores vitamins A, D, and B complex
• Breaks down hormones no longer
useful to the body
• Removes old red blood cells and
recycles iron content
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GALLBLADDER
• The gallbladder stores and
concentrates bile when it is not
needed by the body
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LARGE INTESTINE
• Chyme is semi-liquid food in the
large intestine
• Colon
– Ascending
– Traverse
– Descending
• Anal Canal
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
GENERAL OVERVIEW
OF DIGESTION
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Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine
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COMMON DISORDERS OF
THE DIGESTIVE SYSTEM
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Stomatitis
Gastroesophageal reflux disease
Hiatal hernia
Heartburn
Gastritis
Gastoenteritis
Enteritis
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COMMON DISORDERS OF
THE DIGESTIVE SYSTEM
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Ulcer
Inflammatory bowel disease
Appendicitis
Hepatitis
Cirrhosis
Cholecystitis
Gallstones
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
COMMON DISORDERS OF
THE DIGESTIVE SYSTEM
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Pancreatitis
Diverticulosis
Diarrhea
Constipation
Stomach cancer
Colon cancer
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.