Nutritional Requirements of Animals

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Nutritional Requirements of Animals

• Compare the positive and negative bioenergetics
  of animals
• Name the 3 nutrition needs that must be met by a
  nutritionally adequate diet
• Distinguish among undernourishment, over
  nourishment, and malnourishment
• Explain why fat hoarding may have provided a
  fitness advantage to our hunter-gatherer
  ancestors
• Explain the role of leptin in the regulation of
  fat storage and use
• Define essential nutrients and describe the four
  classes
• Distinguish between water- and fat-soluble
  vitamins.

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Overview of Food Processing

• Define and compare the four main stages of food
  processing
• Compare intracellular and extracellular digestion

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The Mammalian Digestive System

• Describe the processes and structural components
  of the mammalian digestive system
• Name three functions of saliva
• Compare where and how the major types of
  macromolecules are digested and absorbed within
  the mammalian digestive system
• Explain why pepsin does not digest the stomach
  lining. Explain how the small intestine is
  specialized for digestion and absorption
• Explain how the small intestine is specialized
  for digestion and absorption
• Describe the major functions of the large
  intestine

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Evolutionary Adaptations of Vertebrate Digestive
Systems

• Relate variations in dentition and length of the
  digestive system to the feeding strategies and
  diets of herbivores, carnivores, and omnivores
• Describe the roles of symbiotic microorganisms in
  vertebrate digestion

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CHAPTER 41ANIMAL NUTRITION
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FEEDING MECHANISMS

• Suspension feeders sift small food particles from
  the water
• Substrate feeders live on or in their food source
  and eat their way through the food
• Deposit feeders ingest partially decayed organic
  materials along with their substrate
• Bulk feeders ingest large pieces of food

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FOOD PROCESSING

• Ingestion act of feeding
• Digestion process of breaking down food into
  small pieces that the body can absorb (polymers
  to monomers)
• Absorption
• Elimination

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DIGESTION DIVERSITY

• Food vacuoles intracellular digestion (Protozoa
  and sponges)

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Gastrovascular activity

• Digestion sac with a single opening
• Function in both digestion and nutrient
  distribution
• Combination of intracellular and extracellular
  digestion
• Extracelluar digestion allows organism to feed on
  larger food
• Cnidarians and Planarians (flatworms)

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Alimentary canal Digestive tube with two
openings

• One way traffic allows specialization of function
  of different regions - efficient

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MAMMALIAN DIGESTIVE SYSTEM

• Alimentary canal and accessory organs
• Digestive tract has four layered walls
• Mucosa mucous membrane
• Connective Tissue
• Smooth muscle
• Connective tissue attached to membrane of body
  cavity

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• Peristalsis
• Sphincters
• Accessory glands 3 pairs of salivary glands,
  pancreas, liver, gall bladder

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FOOD PATHWAY

• Oral Cavity
• Physical and chemical digestion
• Salivary amylase
• Mucin protection from abrasion, lubrication
• Bolus

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• Pharynx
• Junction for respiratory and digestive systems
• Epiglottis, glottis
• Esophagus
• Muscular tube that conducts food from pharynx to
  stomach via peristalsis

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Stomach

• Large muscular sac, below the diaphragm food
  storage
• Has rugae, folds that expand, and can accommodate
  2 liters of food
• Stomach epithelium secretes gastric juice (HCl
  and pepsin pH 2)

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• Pepsinogen, an inactive protease or zymogen that
  is the precursor to pepsin
• Zymogen inactive form of a protein digesting
  enzyme
• Parietal cells secrete HCl
• Kills bacteria
• Denatures protein
• Starts conversion of pepsinogen to pepsin.
  Pepsin also catalyzes reaction of pepsinogen to
  pepsin
• Pepsin - endopeptidase

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• Gastric pits lead to gastric glands that have
  three types of cells
• Parietal cells
• Mucous cells secrete
• Mucin
• Gastrin a hormone released into blood stream
  and stimulates further secretion of gastric
  juices
• Chief cells secrete pepsinogen
• Pyloric Sphincter regulates passage of acid
  chyme into small intestine

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Helicobacter pylori
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Small Intestine

• 6m in length site of food hydrolysis and
  absorption
• Duodenum (first 25 cm) receives secretion from
• Pancreas
• Hydrolytic enzymes for carbohydrates, lipids,
  proteins, nucleic acids
• Bicarbonate buffer neutralizes stomach acids,
  stimulated by secretin
• Liver produces bile and stores it in the gall
  bladder
• Contains bile salts that emulsify fat
• Cholescystokinin (CCK) Signals gall bladder and
  pancreas to release digestive enzymes (lipase)

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• Pancreatic amylase hydrolyzes starch to maltose
  maltase to glucose
• Protein digestive enzymes (trypsin, chymotrypsin,
  and carboxypeptidase) secreted in active form.
  Activated by enterokinase in lumen of small
  intestine
• Trypsin, chymotrypsin (endopeptidase)
• Carboxypeptidase (exopeptidase) splits from free
  carboxyl group
• Nucleases hydrolyzes DNA and RNA

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Protease Activation
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Fat digestion if fat is present in chyme
Hormone Regulation

• Duodenum secretes enterogastrone, a hormone that
  inhibits peristalsis in stomach, slowing entry of
  food
• CCK stimulates release of bile salts, (emulsify)
  and pancreatic lipase (digest)

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Mice with the inability to produce leptin
(appetite suppressing hormone) results in obesity
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• Jejunum and ileum absorption of nutrients
• Villi, microvilli, brush border
• Lacteal lymph vessels
• Nutrients absorbed by diffusion or active
  transport across 2-cell thick epithelium to
  capillaries or lacteals
• Amino acids and sugars enter capillaries
• Glycerol and fatty acids recombined in epithelial
  cells and enter lacteals
• Capillaries and veins converge at hepatic portal
  vein - liver

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Absorption of nutrients in the small intestine
Structure of the small intestine
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Large Intestine

• 1.5 meters long, inverted U shape
• Reabsorption of water ad fecal production
• E. coli bacteria live on organic material in
  feces source of vitamin K
• Feces are stored in the rectum and passes
  sphincter (one voluntary and one involuntary) to
  anus for elimination

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NUTRITIONAL REQUIREMENTS

• Food as Fuel
• All organic molecules can be used for food
  carbohydrates and fats used first
• Kilocalories energy content of food (1000
  calories)
• Fat 9.5 kc (C)/gram
• Proteins and Carbohydrates (4 C/g)
• Undernourished/Malnourished
• Basal Metabolic Rate (BMR) Number of
  kilocalories (C) a resting animal requires to
  fuel body functions

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Essential Nutrients

• Chemicals an animal requires but cannot
  synthesize
• Amino acids must be obtained in diet
• 8 essential humans cannot manufacture from
  other sources
• 12 can be produced
• Fatty acids unsaturated cannot be produced
• Vitamins organic molecules required in small
  amounts
• Many function as coenzymes
• Water soluble
• Fat soluble
• Minerals inorganic nutrients

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