Chapter 41 Animal Nutrition

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Chapter 41 Animal Nutrition
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A nutritionally adequate animal diet satisfies
three needs
Fuel (chemical energy)
Organic raw materials for biosynthesis
(especially carbon-based molecules)
Essential nutrients (substances that the animal
needs, but cannot synthesize from any precursors
on its own)
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A nutritionally inadequate animal diet fails to
satisfy the three basic needs we just covered
Undernourishment insufficient calories (energy)
Overnourishment too many calories too much
stored fat
Malnourishment a diet missing one or more
essential nutrients
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Energy
Energy in nutrients is measured in Calories
(kcal energy to raise the temperature of 1 L
of water 1º C)
An average human body uses about 1,550
Calories/day
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Principal categories of nutrients
Lipids found in lipid membranes,
etc.including essential fatty acids
9 Calories per gram (a principal energy source)
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Principal categories of nutrients
Proteins building blocks and enzymesanimals
require 20 amino acids, including essential
amino acids
4 Calories per gram (usually a secondary energy
source, since the breakdown of proteins produces
urea, a potentially toxic compound)
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Principal categories of nutrients
Proteins building blocks and enzymesanimals
require 20 amino acids, including essential
amino acids
Fig. 41.10
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Principal categories of nutrients
Carbohydrates C-based building blocks and energy
4 Calories per gram can be a very quick energy
source (e.g., glucose)
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Principal categories of nutrients
Vitamins essential organic molecules required
in small quantities
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Water-Soluble Vitamins excess excreted by
kidneys
Table 41.1
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Fat-Soluble Vitamins can be stored in fat
tissues
Table 41.1
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Principal categories of nutrients
Minerals essential elements and inorganic
molecules (similar to mineral macro- and
micro-nutrients required by plants, but also
including selenium, iodine, etc.)
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Minerals
Table 41.2
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http//www.mypyramid.gov
The food guide pyramidUS Department of
Agriculture
Grains
Fruits
Milk
Vegetables
Oils
Meat Beans
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Food processing
Ingestion food is brought into the digestive
tract
Digestion mechanical and chemical breakdown
(especially via enzymatic hydrolysis, i.e.,
splitting macromolecules into their constituent
monomers)
Absorption cells uptake small molecules that
can be used in biochemical reactions and
biosynthesis
Elimination undigested material passes out of
the body
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Food Processing in Humans
Begins in the mouth
Salivary glands produce saliva that lubricates
the bolus of food
Fig. 41.15
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Food Processing in Humans
Begins in the mouth
Saliva contains amylase, which hydrolyzes starch
Fig. 41.15
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Food Processing in Humans
Begins in the mouth
Saliva also contains some antibodies to help
prevent infections
Fig. 41.15
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Food Processing in Humans
Begins in the mouth
Saliva helps dissolve acids and sugars, so that
they can be detected by the taste buds
Fig. 41.15
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Food Processing in Humans
The muscular tongue manipulates the bolus and
passes it to the pharynx
This triggers the swallowing reflex
Fig. 41.16
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Food Processing in Humans
The larynx moves upward and tips the epiglottis
over the glottis
Fig. 41.16
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Food Processing in Humans
The larynx moves upward and tips the epiglottis
over the glottis
Fig. 41.16
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Food Processing in Humans
Pharynx
Epiglottis
Esophagus
Trachea
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Food Processing in Humans
Pharynx
Epiglottis
?
Esophagus
Trachea
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Food Processing in Humans
Pharynx
Epiglottis
Uvula
Esophagus
Trachea
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Food Processing in Humans
The esophogeal sphincter relaxes, allowing the
esophagus to open
Fig. 41.16
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Food Processing in Humans
Once the bolus has entered the esophagus, the
larynx moves back down, opening the trachea
Fig. 41.16
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Food Processing in Humans
Peristalsis (rhythmic contractions) carries the
bolus to the stomach
Fig. 41.16
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Food Processing in Humans
The stomach is in the upper abdominal cavity,
just below the diaphragm
Fig. 41.15
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Food Processing in Humans
The stomach secretes gastric juice and mixes it
with swallowed food
Gastric juice contains hydrochloric acidand
pepsin
Fig. 41.15
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Food Processing in Humans
Mucus coating helps prevent digestion of the
stomach itself
Fig. 41.15
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Food Processing in Humans
Food and gastric juice become acid chyme
Acid chyme is kept in the stomach by the pyloric
sphincter
Fig. 41.15
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Food Processing in Humans
Digestion continues in the small intestine
Small diameter, muscular tube
Fig. 41.15
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Food Processing in Humans
Digestion continues in the small intestine
In the first section, digestive secretions are
added from the pancreas, gallbladder, and
intestine itself
Fig. 41.15
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Food Processing in Humans
Pancreatic juice
Sodium bicarbonate, which neutralizes the acid
chyme
Fig. 41.19
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Food Processing in Humans
Pancreatic juice
Amylases, lipases, nucleases, proteases (hydrolyti
c enzymes)
Fig. 41.19
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Food Processing in Humans
Bile
Produced in the liver, stored in the gall
bladder, and contains bile salts
Fig. 41.19
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Food Processing in Humans
Bile
A detergent that helps disperse fats into
droplets, thereby aiding their digestion (since
they arrive essentially intact to the first
portion of the small intestine)
Fig. 41.19
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Food Processing in Humans
Most absorption of nutrients occurs in the small
intestine
Fig. 41.15
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Food Processing in Humans
Most absorption of nutrients occurs in the small
intestine
Fig. 41.23
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Food Processing in Humans
Most absorption of nutrients occurs in the small
intestine
Fig. 41.23
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Food Processing in Humans
Folds, villi, and microvilli create a very large
surface area for absorption
Fig. 41.23
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Food Processing in Humans
Capillaries line the core of each villus,
surrounding a lacteal (part of the lymphatic
system)
Fig. 41.23
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Food Processing in Humans
Most nutrients are absorbed into capillaries that
converge in the hepatic portal vessel (leads to
the liver)
Fig. 41.23
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Food Processing in Humans
Fats are absorbed into the lacteals, which lead
through the lymphatic system to large veins of
the circ. system
Fig. 41.23
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Food Processing in Humans
The small intestine meets the large intestine
(colon) at a T-junction
One arm of the T is a cecum and its appendix,
whereas the other arm leads upward
Fig. 41.15
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Food Processing in Humans
Much of the remaining water is absorbed from the
contents of the large intestine
Fig. 41.15
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Food Processing in Humans
Populations of bacteria inhabit the large
intestine some produce vitamins (e.g., B complex
and K)
Fig. 41.15
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Food Processing in Humans
The final compartment is the rectum
Fig. 41.15
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Food Processing in Humans
The final compartment is the rectum
Undigested material is eliminated along with
large quantities of bacteria (dead and alive)
Fig. 41.15
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Digestive Systems are Adapted to their Owners
Lifestyles
Sponges and heterotrophic protists use
intracellular digestion
Waste is expelled byexocytosis
H2O out
H2O ( food) enters pores
Food enters byendocytosis
Food flows into choanocytes
See Fig. 33.4
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Digestive Systems are Adapted to their Owners
Lifestyles
Hydras and most other animals use extracellular
digestion
DigestiveCells
Mouth/Anus
IngestedCrustacean
GastrovascularCavity
See Fig. 41.13
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Digestive Systems are Adapted to their Owners
Lifestyles
Extracellular digestion in a tube (complete
digestive tract or alimentary canal) is the most
efficient and effective
The animal can eat frequently, even while
digesting the previous meal
Specialized compartments and digestive organs
can contribute to the process sequentially
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Digestive Systems are Adapted to their Owners
Lifestyles
Extracellular digestion in a tube (complete
digestive tract or alimentary canal) is the most
efficient and effective
Intestine
Anus
Mouth
Esophagus
Crop
Gizzard
Pharynx
See Fig. 41.14
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Digestive Systems are Adapted to their Owners
Lifestyles
Like earthworms, birds lack teeth, so their
muscular gizzards help break apart hard food
particles
Stomach
Esophagus
Rectum
Crop
Gizzard
Anus / Cloaca
Intestine
See Fig. 41.14
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Digestive Systems are Adapted to their Owners
Lifestyles
Animal digestive systems cannot break down
cellulose
Ruminant animals (cows, sheep, etc.) have
stomachs with several chambers
The first two are fermentation vats with
microbes that produce cellulase
Fig. 41.28
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Digestive Systems are Adapted to their Owners
Lifestyles
Vertebrate dentition generally matches the diet
An adult human has 32 teeth Incisors for
cutting Canines for tearing Premolars and
molars for grinding
Fig. 41.26
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Digestive Systems are Adapted to their Owners
Lifestyles
Vertebrate intestines generally match the diet
Fig. 41.27
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Digestive Systems are Adapted to their Owners
Lifestyles
Digestive enzymes generally match the diet
E.g., most adult mammals do not produce lactase