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 doesnt 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 doesnt the small intestine digest itself?
Fig. 37.13
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(No Transcript)
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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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What would happen if you had a defect in salivary
amylase production?

• 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

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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 enzyme cellulase
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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