Download Digestive System

12/22/2016
The Digestive System
Learning
About Our
Guts
• Adult humans have a digestive tract
that ranges from 6.5m to 9m
• Although it is one continuous tube, it
can be broken down into specialized
segments
• Ingestion occurs when food is put into
the mouth
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The Mouth
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Swallowing
• Mechanical and chemical digestion both
begin in the oral cavity (mouth)
Mechanical
– Food is ground down by teeth and formed
into bolus by tongue
Chemical digestion
– Saliva aids the chemical breakdown of
carbohydrates
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The Esophagus
• Esophagus – muscular tube through which food
passes from the mouth to the stomach
• Bolus activates peristalsis
– Involuntary rhythmic muscle contraction moves
the bolus down esophagus into the stomach
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12/22/2016
The Stomach
-Mechanical-
The Stomach
Anatomy of the Stomach
• Rugae - stomach walls are folded, allows for
expansion when full
• Stomach also undergoes peristalsis
to continue mechanical
digestion and mixing of food
with gastric juices
Chemical Digestion
• Gastric juices – secreted by
glands in stomach
• Mixture of HCl(aq), salts,
enzymes, water, and mucus
• Mucus protects stomach
lining from being digested by
gastric juices
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The Intestines
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Accessory Organs
• Contains both the large and small
intestines
• Most digestion occurs in the small
intestine
• Small intestine is up to 7m in length,
2.5cm in diameter
• Large intestine is also known as
colon
• Absorbs water from the waste and
contains billions of bacteria
Pancreas
• Secretes 1L of pancreatic
fluid into small intestine
daily
• Pancreatic fluid contains
enzymes to digest
carbohydrates, lipids,
proteins
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Accessory Organs
Accessory Organs
Liver
• Largest internal organ (1.5kg)
• Secretes bile, a greenishyellow fluid
• Helps to digest fat
Gall Bladder
• Stores bile that is created
in liver
• Contains bile salts
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