AP

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Chapter 41.
Animal Nutrition
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Nutritional requirements

• Animals are heterotrophs
• need to take in food
• Why? fulfills 3 needs
• fuel chemical energy for production of ATP
• raw materials carbon sources for biosynthesis
• essential nutrients substances animals cannot
  make themselves
• elements (N, P, K, Fe, Na, K, Ca, etc.), NAD,
  FAD, etc.

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Energy budget

basal (resting) metabolism activity
temperature regulation
food intake
ATPproduction

growth reproduction
biosynthesis

glycogen fat
storage
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Energy budget

• The flow of food energy into out of an animal
  can be viewed as a budget
• if animal takes in more calories than it needs to
  produce ATP, bank the rest
• excess used for biosynthesis storage
• growth in size
• reproduction
• stored in energy deposits

This obese mouse (L) has defect in gene which
normally produces an appetite-regulating protein
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Energy storage

• In humans
• store as glycogen
• glucose polymer
• storage in liver muscle cells
• If glycogen stores are full caloric intake
  still exceeds caloric expenditure
• excess stored as fat

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Managing caloric intake

• When fewer calories are taken in than are
  expended, fuel is taken out of storage deposits
  oxidized (digested)
• breakdown glycogen from liver muscle cells
• metabolize (digest) fat

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Regulation Maintaining Homeostasis

• Balancing glucose levels in blood

glucose uptake
pancreas
insulin
depress appetite
glucose storage
glucose release
stimulatehunger
pancreas
glucagon
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Managing glucose levels

• Human body regulates the use storage of
  glucose, a major cellular fuel
• insulin reduces blood glucose levels
• when glucose levels rise above set point,
  pancreas secretes insulin
• promotes transport of glucose into cells
  storage of glucose as glycogen in liver muscle
  cells
• dropping blood glucose levels
• glucagon increases blood glucose levels
• when glucose levels drop below set point,
  pancreas secretes glucagon
• promotes breakdown of glycogen release of
  glucose into the blood
• increasing blood glucose levels

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Nutritional requirements
Many herbivores have diets deficient in mineral
salts. Must find other sources salt licks,
chewing on bones

• Fuel for ATP production
• Raw materials for biosynthesis
• source of N P
• to make complex molecules proteins, nucleic
  acids
• need complex molecules animals cannot synthesize
• amino acids, vitamins
• need minerals
• iron, calcium, etc.

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Vegetarian diets

• 8 essential amino acids
• what about the other 12? we can synthesize them!
• Possible amino acid deficiency can be avoided by
  eating foods with complementary amino acids
• beans grains

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Essential Nutrients

• What happens if an animals diet is missing an
  essential nutrient?
• deficiency diseases
• scurvy vitamin C (collagen production)
• rickets vitamin D (calcium absorption)
• blindness vitamin A (retinol production)
• anemia vitamin B12 (coenzyme function)
• kwashiorkor protein

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Essential vitamins (coenzymes)
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Essential vitamins (coezymes)
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Essential minerals (cofactors)
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Dietary regimes

• All animals eat other organisms
• Herbivores
• eat mainly autotrophs (plants, algae)
• gorillas, cows, hares, snails
• Carnivores
• eat other animals
• sharks, hawks, spiders, snakes
• Omnivores
• consume animals plants or algae
• cockroaches, bears, raccoons, humans
• humans evolved as hunters, scavengers gatherers

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Feeding adaptations
suspension feeding
substrate feeding
fluid feeding
bulk feeding
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Food processing

• Ingestion
• eating
• Digestion
• breaking food down into molecules small enough
  for the body to absorb
• enzymatic hydrolysis
• Absorption
• animal cells take up small molecules
• Elimination
• undigested material passes of digestive system

intracellulardigestion
extracellulardigestion
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Digestive systems
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Mammalian digestive system

• Alimentary canal
• peristalsis
• push food along by rhythmic waves of smooth
  muscle contraction in walls of digestive canal
• sphincters
• muscular ring-like valves, regulate the passage
  of material between specialized chambers of
  digestive canal
• Accessory glands
• salivary glands, pancreas, liver gall bladder
• secrete digestive juices (enzymes fluid)

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Human digestive system
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Swallowing

• Mouth ingests
• mechanical digestion chemical digestion of
  starch
• Epiglottis
• closes trachea when swallowing
• problem breathe swallow through same orifice
• Esophagus
• moves food to stomach by peristalsis

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Ingestion

• Mouth, pharynx esophagus
• physical chemical digestion of food
• trigger reflexive release of saliva from salivary
  glands, containing
• mucin
• slippery glycoprotein
• protects soft lining of mouth from abrasion
  lubricates food for easier swallowing
• buffers
• help prevent tooth decay by neutralizing acid in
  mouth
• antibacterial agents
• kill bacteria that enter mouth with food
• amylase
• digests starch glycogen

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Throat

• Pharynx
• junction that opens to both esophagus
  trachea (windpipe)
• swallowing
• top of windpipe moves up so opening glottis
  blocked by cartilaginous flap epiglottis
• ensures that food will be guided into entrance of
  esophagus not directed down windpipe

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Stomach

• Food storage
• can stretch to fit 2L food fluid
• Digestion
• gastric juice
• digestive fluid secreted by epithelial lining
• HCl
• pH 2
• breaks down matrix binding cells
• kills bacteria
• pepsin
• breaks down proteins
• secreted as pepsinogen
• mucus
• protects stomach lining

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Helicobacter pylori
Coevolution of parasite host
Free of H. pylori
Colonized by H. pylori

• Bacteria-stomach feedback interactions
• H. pylori bacteria colonize stomach
• bacterial infection
• causes damaging inflammation
• increases stomach acidity
• high rate of ulcer stomach cancer
• control with antibiotics

inflammation of stomach
inflammation of esophagus
H. pylori
cell damaging proteins (VacA)
inflammatory proteins (CagA)
cytokines
helper T cells
neutrophil cells
white blood cells
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Small intestine

• Major organ of digestion absorption
• over 6 meters!
• 3 sections
• duodenum most of digestion
• jejunum absorption of nutrients water
• ileum absorption of nutrients water
• absorption through lining of intestines
• small intestine has huge surface area 300 m2
  (roughly size of tennis court)

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Duodenum

• Acid material from stomach mixes with digestive
  juices from glands
• pancreas, liver, gall bladder glandular cells
  of intestinal wall

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Pancreas

• Digestive enzymes
• peptidases
• trypsin
• trypsinogen
• chymotrypsin
• chimotrypsinogen
• carboxypeptidase
• procarboxypeptidase
• amylase
• Buffers
• lowers pH
• alkaline solution rich in bicarbonate (HCO3-)
• buffers acidity of material from stomach

Explain how this is a molecular example of
structure-function theme.
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Digestive enzymes
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Liver

• Many functions in body
• digestive system
• production of bile
• stored in gallbladder until needed
• act as detergent to help digest absorb fats
• circulatory system
• toxin damaged red blood cell removal
• bile contains pigment by-products of RBC
• bile pigments eliminated from body with feces
• brown feces rusty iron from hemoglobin!

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Absorption
Explain how this is a structural example of
structure-function theme

• Villi
• increase surface area

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Absorption of Nutrients

• Passive
• fructose
• Active (protein pumps)
• pump amino acids, vitamins glucose
• against concentration gradients across intestinal
  cell membranes
• allows intestine to absorb much higher proportion
  of nutrients in the intestine than would be
  possible with passive diffusion
• worth the cost of ATP!

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Large intestines (colon)

• Reclaiming water
• used as solvent for various digestive juices
• 7L of fluid secreted intodigestive tract daily
• gt 90 of water reabsorbed
• diarrhea insufficient water absorbed
• constipation too much water absorbed

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Flora of large intestines

• Living in the large intestine is a rich flora of
  mostly harmless bacteria
• Escherichia coli
• a favorite research organism
• bacteria produce vitamins
• vitamin K biotin, folic acid other B vitamins
• generate gases
• by-product of bacterial metabolism
• methane, hydrogen sulfide

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Rectum

• Terminal portion of colon
• Feces contain
• masses of bacteria
• undigested materials, mainly cellulose
• roughage or fiber
• salts

appendix
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Structural adaptations

• Structural variations reflecting diet have made
  mammals very successful
• differences in teeth
• length of digestive system
• number size of stomachs

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Teeth

• evolutionary adaptation of teeth for processing
  different kinds of food

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Length of digestive system

• Herbivores omnivores
• long digestive systems
• harder to digest cellulose (cell walls)
• Carnivores
• short digestive systems

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Digesting cellulose

• How well you digest cellulose governs life
  strategy of herbivores

starch vs. cellulose
position of glycosidic linkage governs
digestibility
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• Cow
• can digest cellulose well no need to eat
  supplemental sugars
• Gorilla
• cant digest cellulose well must supplement with
  sugar source, like fruit

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Symbiotic organisms

• How can cows digest cellulose efficiently?
• symbiotic bacteria protists help digest
  cellulose-rich meals of herbivores

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Any Questions??