Download Small intestine Herbivore

Animal Nutrition
Ch. 41
Lecture Objectives
1. Importance of Food
2. Stages of Food Processing
3. Mammalian Alimentary Canal
An Animals Diet Must Provide
1. Chemical energy for cellular processes
2. Organic building blocks for macromolecules
3. Essential nutrients (amino acids, fatty acids, vitamins, and minerals)
- lack of can cause deformities, disease, and death
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Figure 41.3
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Four Stages of Food Processing
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Figure 41.5
1 INGESTION
Mechanical
digestion
2 DIGESTION
3 ABSORPTION
4 ELIMINATION
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Chemical
digestion
(enzymatic
hydrolysis)
Nutrient
molecules
enter
body cells
Undigested
material
Suspension Feeders and Filter Feeders
Baleen
Types of Feeders
Substrate
Feeders
Fluid Feeders
Caterpillar Feces
Bulk Feeders
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Figure 41.6
Digestive Compartments
1. Most animals process food in specialized compartments
2. These compartments reduce the risk of an animal digesting
its own cells and tissues
- Intracellular Digestion: food particles are engulfed by
phagocytosis  food vacuoles, containing food, fuse with
lysosomes containing hydrolytic enzymes (i.e. sponges)
- Extracellular Digestion: breakdown of food particles
outside of cells in compartments that are continuous with
the outside of the animal’s body (gastrovascular cavities)
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Figure 41.7
Mouth
Tentacles
1 Digestive enzymes
Food
are released from a
gland cell.
2 Enzymes break
food down into small
particles.
3 Food particles are
engulfed and digested
in food vacuoles.
Epidermis
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Gastrodermis
Alimentary Canals
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Figure 41.8
Crop
Esophagus
Gizzard
Intestine
Pharynx
Anus
Mouth
(a) Earthworm
Foregut
Midgut
Hindgut
Rectum
Anus
Esophagus
Mouth
(b) Grasshopper
Crop
Stomach
Gastric cecae
Gizzard
Intestine
Mouth
Esophagus
Crop
(c) Bird
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Anus
Figure 41.9
Tongue
Oral cavity
Salivary
glands
Pharynx
Mouth
Esophagus
Liver
Gallbladder
Pancreas
Sphincter
Rectum
Anus
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Gallbladder
Liver
Sphincter
Stomach
Small
intestine
Large
intestine
Esophagus
Pancreas
Anus
Duodenum of
small intestine
Salivary
glands
Stomach
Small
intestine
Large
intestine
Rectum
The Oral Cavity, Pharynx, and Esophagus
1. Oral cavity
- Masticate Food
- Salivary glands
- mucus, antibacterials, buffers, & amylase
- Chew food into the shape of a bolus
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2. Esophagus & Peristalsis
Bolus of
food
Tongue
Epiglottis
up
Pharynx
Esophageal
sphincter
contracted
Glottis
Larynx
Trachea
Esophagus
Epiglottis
down
Glottis up
and closed
Esophageal
sphincter
relaxed
To To
lungs stomach
(a) Trachea open
(b) Esophagus open
Figure 41.10
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Figure 41.11
Stomach
Gastric pit
on the interior
surface of
stomach
3. Stomach & Gastric Juices
(Mucus, HCl, Pepsinogen &
Pepsin)
Epithelium
3
Pepsinogen
Gastric gland
Mucous cell
Chief cell
Parietal cell
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Chief
cell
Pepsin
(active
HCl enzyme)
2
1
Cl−
H+
Parietal
cell
4. Small Intestine: Duodenum
1
Gallbladder
Liver
Stimulation
Inhibition
Food
Stomach
Gastric Gastrin
juices
Pancreas
Duodenum of
small intestine
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Figure 41.20a
Figure 41.12
CARBOHYDRATE DIGESTION
ORAL
CAVITY,
PHARYNX,
ESOPHAGUS
Polysaccharides Disaccharides
(starch, glycogen)
(sucrose, lactose)
Salivary amylase
Smaller
Maltose
polysaccharides
PROTEIN DIGESTION
Proteins
STOMACH
Pepsin
Small polypeptides
SMALL
INTESTINE
(enzymes
from
pancreas)
Pancreatic amylases
Disaccharides
Pancreatic trypsin and
chymotrypsin
NUCLEIC ACID DIGESTION
FAT DIGESTION
DNA, RNA
Fat (triglycerides)
Pancreatic
nucleases
Nucleotides
Pancreatic lipase
Smaller
polypeptides
Pancreatic carboxypeptidase
Glycerol, fatty acids,
monoglycerides
Small peptides
SMALL
INTESTINE
(enzymes
from
intestinal
epithelium)
Nucleotidases
Disaccharidases
Monosaccharides
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Dipeptidases, carboxypeptidase, and
aminopeptidase
Amino acids
Nucleosides
Nucleosidases
and
phosphatases
Nitrogenous bases,
sugars, phosphates
5. Small Intestine: villi, microvilli & absorption
Vein carrying
blood to liver
Blood
capillaries
Microvilli
(brush border)
at apical (lumenal)
surface
Villi
Epithelial
cells
Lumen
Epithelial
cells
Muscle layers
Intestinal
wall
Nutrient
absorption
Villi
Large
circular
folds
(toward
capillary)
Lacteal
Lymph
vessel
Basal
surface
Figure 41.13
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6. Large Intestine
Ascending
portion
of colon
Small
intestine
Appendix
Cecum
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Figure 41.15
Stomach and Intestinal Adaptations
1. Carnivores  large, expandable stomachs
2. Herbivores & Omnivores  longer alimentary canals than
carnivores, reflecting the longer time needed to digest
vegetation
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Figure 41.17
Small intestine
Small
intestine
Stomach
Cecum
Carnivore
Colon
(large
intestine)
Herbivore
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Figure 41.19
Reticulum
Rumen
Esophagus
3
Intestine
Omasum
2
1
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Abomasum
4