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Animal Nutrition
Requirements and Utilization
Nutritional Requirements
• heterotrophs require nutrition to supply
– energy
• sources
–fats - 9.5 kcal/g
–carbohydrates - 4.2 kcal/g
–proteins - 4.1 kcal/g
• storage molecules
• basal metabolic rate
–1300-1800 kcal/day
use of energy stores during starvation
Figure 50.3
Nutritional Requirements
• heterotrophs require nutrition to supply
– carbon skeletons
• acetyl groups - from fats, carbohydrates,
or proteins
• essential amino acids - from proteins
• essential fatty acids - from fats/oils
acetyl group is an essential dietary requirement
Figure 50.4
essential amino acids from plant products
Figure 50.5
Nutritional Requirements
• heterotrophs require nutrition to supply
– metabolic & structural factors
• mineral nutrients - various sources
• vitamins (coenzymes, etc.) - various
sources
mineral elements
and vitamins
Tables 50.1, 50.2
Feeding Adaptations
• heterotrophs have adaptations suited to their
food sources
– mammalian teeth
• share common structure
• differ in shape, distribution, and use
exposed
enamel,
bony dentine,
sensitive pulp
cavity
Figure 50.7
the
type
and arrangement of
teeth
reflect
an
animal’s
diet
Figure 50.7
Digestive Anatomy
• tubular gut
– extends from mouth to anus
– creates an enclosed extra-cellular chamber
– includes sequential functional segments
• mouth & buccal cavity (or gizzard)
–intake & fragmentation of food
• stomach (or crop)
–storage of large meals
– +/- digestion
Digestive Anatomy
• tubular gut
– (small) intestine
• enzymatic digestion
• absorption of biomolecule subunits
– hindgut (large intestine)
• reabsorption of water & ions
• storage of undigested materials
– rectum
• expulsion of feces from anus
tubular
digestive
systems
Figure 50.8
increased intestinal surface area
Figure 50.9
length, folds, villi, microvilli
Figure 50.9
Digestive Anatomy
• intestinal adaptations
– symbiotic bacteria or protists
– modifications to increase surface area
– secretion of hydrolytic digestive enzymes
• zymogens activated in intestine
• biomolecules digested to monomers
human
digestive
system
Figure
50.10
Digestive Anatomy
• human digestive system
– structure of the tube
• lumen, surrounded by
• mucosa
–secretes mucus, enzymes, HCl
–absorbs nutrients
Digestive Anatomy
• human digestive system
– structure of the tube
• submucosa
–blood & lymph vessels
–sensory/regulatory nerve network
• two muscle layers
–circular muscle layer
–longitudinal muscle layer
–nerve network
Digestive Anatomy
• human digestive system
– structure of the tube
• serosa - outer jacket layer
• peritoneum - surrounding membrane
layers
of the
tubular
gut
Figure
50.11
Function of the Gut
• human digestive system
– food moves through the gut by peristalsis
• propulsive wave of smooth muscle
contraction
• control points employ sphincter muscles
Function of the Gut
• human digestive system
– digestion begins in the mouth
• chewing & salivary secretions initiate
food breakdown
• swallowing maneuvers food
–through the pharynx
–over the epiglottis
–into the esophagus
• peristalsis delivers food to the stomach
swallowing is a series of reflex actions
Figure 50.12
peristaltic
transport
Figure
50.12
Function of the Gut
• human digestive system
– digestion continues in the stomach
• gastric mucosa secretes digestive
substances
–mucus - protects mucosa
–HCl - maintains pH ~2
–pepsinogen
»endopeptidase
»activated by low pH & autocatalysis
stomach
secretions
Figure
50.13
activation of pepsinogen
Figure 50.14
Function of the Gut
• human digestive system
– digestion continues in the stomach
• chyme
–product of digestion & mixing
–propelled into the small intestine
through the pyloric sphincter
Function of the Gut
• human digestive system
– digestion & absorption in small intestine
• duodenum
–receives chyme
–receives bile
»produced in the liver
»stored in the gall bladder
»delivered through common bile duct
»emulsifies fats into micelles
bile
production,
storage
and
delivery
to the
small
intestine
Figure
50.15
Sources & functions of digestive enzymes
Table 50.3
Function of the Gut
• human digestive system
– digestion & absorption in small intestine
• duodenum
–digests molecules
»peptides => amino acids
»disaccharides => monosaccharides
»fats => monoglycerides, fatty acids
Function of the Gut
• human digestive system
– digestion & absorption in small intestine
• jejunum & ileum
–absorb monomeric subunits
»ions & nutrients enter by
> active transport
> co-transport
> facilitated diffusion
Function of the Gut
• human digestive system
– digestion & absorption of fats
• monoglycerides & fatty acids
–enter microvilli
–re-assembled
–combined with cholesterol &
phospholipids into chylomicrons
–delivered to blood in lymph
absorption
of the
products
of
lipid
digestion
Figure 50.16
Function of the Gut
• human digestive system
– water and ion absorption in the colon
• peristalsis moves the remains to the colon
• water & ions are removed from the slurry
• vitamin K & biotin are produced by E.
coli
Regulation of Gut Activities
• autonomic reflexes coordinate activities in
different parts of digestive tract
– e.g. salivation, swallowing, etc.
• hormonal signals control digestive activities
– e.g. pancreatic secretion, bile release, etc.
hormonal
control of
digestion
Figure 50.18
Regulation of Fuel Metabolism
• absorptive period supplies nutrients to the
body
– glucose stored as glycogen or fat
– monoglycerides & fatty acids stored as fat
– amino acids stored as blood plasma
proteins or converted to glucose
(gluconeogenesis)
hormonal
control of
blood
glucose
Figure 50.19
fuel
transport
and
metabolism
during
absorptive
period
Figure 50.20
Regulation of Fuel Metabolism
• post-absorptive period utilizes stored
nutrients
– fuel molecules return to blood when needed
fuel
transport
and
metabolism
in postabsorptive
period
Figure 50.20