Animal Nutrition II (Ch. 41)
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Transcript of Animal Nutrition II (Ch. 41)
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Animal Nutrition II (Ch. 41)
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Keywords
• Roles of mouth, stomach, sm.&lg. Intestine in digestion
• Pepsin, pepsinogen• Villi, microvilli• Cecum• Cellulose• Cellulase
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Stomach
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Digestive mechanisms in
stomach
• Mechanical
• Chemical
• enzymatic
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Mechanical
• Mixing and churning
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Chemical
• pH around 2– Also breaks food down
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Enzymatic
• Pepsin– Breaks down proteins
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Why doesn’t pepsin digest
stomach?
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Activation of pepsin
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Small intestine
• Most of the enzymatic digestion occurs here
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Table 41.13 p. 803 in Campbell
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Why doesn’t the small intestine digest itself?
Fig. 37.13
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Most nutrient absorption takes place in small
intestine• Structure: another
example of increasing surface area
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Structure of small intestine
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Microvilli
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Large intestine (colon)
• Major function is to reabsorb water
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Here are a few review questions
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What would happen if you had a defect in pepsin production?
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What would happen if you had a defect in pepsin production?
• A. carbohydrate would not be digested well
• B. meat would not be digested at all
• C. perhaps decreased absorption of protein
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What would happen if you had a defect in salivary amylase
production?
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• A. You would die
• B. You would be unable to digest starch
• C. The pH of the stomach would be affected
• D. None of the above
What would happen if you had a defect in salivary amylase
production?
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Which of the following would you least like to donate to science
while you are still alive?• A. Cecum
• B. Pancreas
• C. Reproductive organs
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What would happen if you had a defect in small intestine
enteropeptidase?
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Variations of vertebrate digestive system
• Herbivorous mammals– Specialized fermentation chambers
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Coyote vs. Koala
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Why does herbivory require specializations?
• Plant tissue– Harder to break up– Contains cellulose– Nutrients less concentrated than meat
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Structure of cellulose
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Only bacteria and protozoa can break down cellulose
Via the enzymecellulase
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Cecum
• Pouch at junction between lg and sm intestine
• Large cecum in rabbits, some rodents, koala, horses
• Full of symbiotic bacteria
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Symbiosis
• “living together”
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Cecum function
• Fermentation chamber
• Bacteria breakdown cellulose
• Feces must be reingested