Chapter 41: Animal Nutrition
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Figure 41.0 Animals eating: foal, bear, and stork
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Chemoheterotroph: requires food for
1.
2.
3.
Figure 41.1 Homeostatic regulation of cellular fuel
Glucose: maintain 65-100 mg/dL
 Glucagon
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Figure 41.2 A ravenous rodent
Figure 41.3 Obtaining essential nutrients

Insulin

Diabetes
Leptin
 Produced by adipose cells
 Increase in adipose cells  increase leptin secrete decrease appetite
 Decrease in fat  decrease leptin produced  increase appetite.
Prader Willi Syndrome
 Rarely inherited
 Due to deletion on a gene of chromosome 15
 Always feel hungry
 Usually eat  release dopamine  satisfied
 Gene for one GABA receptor defective (gammaaminobutyric acid)
 3 x more GABA in blood than normal
 GABA inhibits dopamine
Essential Nutrients

Malnourished: missing essential nutrients.
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Figure 41.4 Essential amino acids from a vegetarian diet
Essential Amino Acids
 Body requires 20
 8 are essential (obtained from food)
 Meat/animals  complete—all essential aa
 incomplete—deficient
o corn and beans
**vegetarians must be careful to take in all amino acids through diet.
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Figure 41.5 Storing protein for growth
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Table 41.1 Vitamin Requirements of Humans: Water-Soluble Vitamins
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Table 41.1 Vitamin Requirements of Humans: Fat-Soluble Vitamins
Vitamins
 .01-100 mg/day
 Organic molecule required in diet in small amounts
 Variety of functions
o Cofactors for enzymes
o A incorporated into visual pigments
o C helps in formation of collagen
o Folic acid
 Development of DNA
 Cell growth/develop, tissue formation
 Lack  birth defect (spina bifida)
 Water soluble or fat soluble
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Table 41.2 Mineral Requirements of Humans
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Figure 41.6 Suspension-feeding: a baleen whale
Minerals
 Simple inorganic nutrients
 Require <1mg – 2500 mg/day
 Ca and P for bone
 Ca for nerve/muscle
 P for ATP/nucleic acids
 Mg, Fe, Zn, Cu, Mn, Se, Mb: cofactors for enzumes
 Na, K, Cl, nerve function
Heterotrophs
 Herbivore
 Carnivore: shark, hawk, snake
 Omnivore: humans
Organisms are adapted for feeding.
Suspension feeder
 Baleen whale, aquatic
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Figure 41.7 Substrate-feeding: a leaf miner
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Figure 41.8 Fluid-feeding: a mosquito
Substrate feeder
 Live in/on food
 Eat way through
 Maggots, insect larvae
Fluid feeder
 Suck fluid from host
 Mosquito, leech, aphid, humming bird
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3
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Mosquitoes
Figure 41.9 Bulk-feeding: a python
Bulk Feeder
 Most animals
 Large pieces of food
 Tentacles, claws, teeth, fangs
Four stages of digestion
1.
2.
3.
4.
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Figure 41.10 Intracellular digestion in Paramecium
Specialized compartments
 at all levels (simple to complex)
 prevent self digestion
Intracellular digestion
 food vacuole
 protests, sponge
 fuse with lysosome which contains hydrolytic enzymes
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Figure 41.11 Extracellular digestion in a gastrovascular cavity
Extracellular digestion
 breakdown food ____________ cells.
 compartment continuous with outside of body
Gastrovascular Cavity
 simple
 cnidarian, flatworm
 allow larger prey than phagocytosis
 digest in cavity, absorb nutrients
 transport relies on diffusion through cells
 Food in/Waste out same opening
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Figure 41.12 Alimentary canals
Complete digestive tract
 Alimentary canal
 Food moves in one direction
 Specialized regions
Mouth/pharynx  esophagus  crop/gizzard/stomach  intestine 
anus
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Figure 41.13 The human digestive system
Mammalian Digestive System
 Peristalsis: smooth muscle, rhythmic contraction, move food
 Sphincters: ring of smooth muscle, close off regions
o Cardiac, pyloric, anal

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Figure 41.14 From mouth to stomach: the swallowing reflex and esophageal
peristalsis (Layer 1)
Accessory Glands
o Salivary, pancreas, liver, gall bladder
o Part of digestive system—but no food through
o Liver – produce bile, stored in gall bladder.
Stomach: 2-6 hours
SI: 5-6 hours
LI: 12-24 hours
Total: 19-36 hours
Oral Cavity
 Physical and chemical breakdown
 Physical  increase SA, make easy to swallow/digest

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Figure 41.14 From mouth to stomach: the swallowing reflex and esophageal
peristalsis (Layer 2)
Saliva
o
o
o
o
1L/day
Buffer, kill bacteria
Mucin: lubricates (glycoprotein)
Salivary amylase—hydrolyze starch and glycogen
 Bolus sent to pharynx
Pharynx
 Open to esophagus and trachea
Epiglottis
 Cartilaginous flap
 Block windpipe when swallow
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Figure 41.14 From mouth to stomach: the swallowing reflex and esophageal
peristalsis (Layer 3)
1. no swallowing: epiglottal sphincter closed  epiglottis up, glottis
open
2. bolus at pharynx  swallow (reflex)
3. larynx up (can feel)  top epiglottis over glottis
4. esophageal sphincter relaxes
5. larynx down, food  esophagus
Animation
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Figure 41.15 Secretion of gastric juice
Stomach
 2L, can stretch
 Gastric juice from epithelium
ANIMATION
H. Pylori



Parietal cells  HCl; pH = 2
Acid breaks up cells of plant and meat
Acid kills bacteria


Chief Cells: pepsinogen (zymogen)
Pepsinogen cut by HCl  pepsin (digest proteins)
o Does not break into individual aa
o Breaks proteins into smaller pieces.
Positive feedback: pepsin activates pepsinogen

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Figure 41.16 The duodenum
Fatty Acid Digestion
Protected by mucous coat
Constant erosion of epithelium—replace every 2 days.
Cardiac orifice: at entry to stomach (cardiac sphincter)
Pyloric Sphincter: entry to SI from stomach
Acid chime: nutrient rich broth, sent to intestines from stomach
Small Intestine
 6m long (longer than LI, but small diameter)
 Three regions: duodenum, jejunum, ileum
Added slide with amino
acid/protein picture
Duodenum
 1st 25cm
 Acid chime mix with secretions from pancreas, liver, gall bladder.
 Liver/GB  bile—emulsify fat, lipases to break down fat.
 Pancreas  bicarbonate (neutralize acid)
Carbohydrate Breakdown
 Pancreatic amylase: break starch/glycogen to smaller poly and
disaccharides
 Maltase, lactase, sucrase. . break to monosaccharides
Protein Breakdown
 Trypsin and chymotrypsin
o Both from pancreas
o Break large pp to shorter pp (not to indiv aa)
 Carboxypeptidase (pancreas)
o Break polypeptides to indiv aa from carboxyl side
 Aminopeptidase (intestinal epithelium)
o Break polypeptide to indiv aa from amino side
Nucleic Acids
Nucleases
Fats
Lipases
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Figure 41.17 Enzymatic digestion in the human digestive system
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Figure 41.18 Activation of protein-digesting enzymes in the small intestine
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Figure 41.19 The structure of the small intestine
Jejunum and Ileum absorb nutrients and water
Surface area ~ 300m2 (tennis court)
Villi: finger like projections
Microvilli on villi.
Capillaries
 Amino acids and sugars to capillaries
 Hepatic portal vessel—blood directly to liver—first access to
nutrients.
Lacteal
 Fat and cholesterol coated with proteins  chylomicrons
 Exocytosis into lacteal
 Through lymphatic system to blood
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Figure 41.x1 Large intestine
Absorb 80-90% organic material
Most undigested = cellulose
Large Intestine = Colon
1.5 m
Recover water
Feces out
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Figure 41.20 Dentition and diet
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Figure 41.21 The digestive tracts of a carnivore (coyote) and a herbivore (koala)
compared
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Figure 41.22 Ruminant digestion
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Figure 41.x2 Termite and Trichonympha