1. Animal Nutrition
Chapter 41

2. 3 main categories of feeding:
Herbivores – Plants & algae
Carnivores – Meat
Omnivores – Both

3. 3 needs: Fuel (ATP) Organic matter for biosynthesis
Essential nutrients - vitamins

4. Four Main Feeding Mechanisms of Animals
SUSPENSION FEEDERS
SUBSTRATE FEEDERS
Feces
Baleen
Caterpillar
FLUID FEEDERS
BULK FEEDERS

5. Feeders Suspension – Sift food from H20 (strainer)
Substrate – Live in or on food
Fluid – Suck nutrients from host
Bulk – Large pieces

6. Glucose regulation
Liver and muscle cells store energy in the form of glycogen (extra stored as fat)
Regulation – Negative feedback
Thermostat in house

7. STIMULUS:
Blood glucose
level rises
after eating.
Homeostasis:
90 mg glucose/
100 mL blood
level drops
below set point.
When blood glucose
level rises, a gland called
the pancreas secretes insulin,
a hormone, into the blood. 1
Insulin enhances the transport of glucose into body cells and stimulates the liver and muscle cells to store glucose as glycogen. As a result, blood glucose level drops. 2
When blood glucose level drops, the pancreas secretes the hormone glucagon, which opposes the effect of insulin. 3 4
Glucagon promotes the breakdown
of glycogen in
the liver and
there lease of Glucose into the
blood,increasing
blood glucose level.

8. 41.2 Animal’s diets must supply carbon skeleton and essential nutrients
Make Carbohydrates, Proteins and lipids from sugar and nitrogen.
Essential nutrients – can’t make must get from food pre-made
Amino acids – 20 (meat, cheese, animal products)
Fatty acids – unsaturated easily attained in diet
Vitamins – 13 essential – H20 soluble & fat soluble
C, A, D, E , K
Minerals - Inorganic nutrients – Calcium, Phosphate, Iron, Zinc

9. Obtaining essential nutrients

10. Essential amino acids from a vegetarian diet
Corn (maize) and other grains
Beans and other legumes
Essential amino acids for adults
Methionine
Valine
Threonine
Phenylalanine
Leucine
Isoleucine
Lysine
Tryptophan

11. 41.3 Stages of food processing
Organic material in food – fats, proteins, and carbohydrates
Steps of digestion:
1. Ingestion – Eating
2. Digestion – Breaking down food into molecules small enough for the body to absorb

12. The four stages of food processing
Pieces of food
Small molecules
Mechanical digestion
Food
Chemical digestion (enzymatic hydrolysis)
Nutrient molecules enter body cells
Undigested material
INGESTION 1
DIGESTION 2
ELIMINATION 4
ABSORPTION 3

13. 3. Absorption – Cells take up small molecules
4. Elimination – Undigested material passes

14. Risk of digesting one’s self?
No – Specialized compartments
Intracellular – One cell/Sponges
Extracellular – Breaking down food outside cells

15.  Digestion in a hydra
Gastrovascular cavity
Food
Epidermis
Mesenchyme
Gastrodermis
Mouth
Tentacles
Food vacuoles
Gland cells
Flagella
Nutritive muscular cells
Gastrovascular Cavity - Sac with a single opening – Hydras, Jellies & flatworms

16. Variation in alimentary canals
Earthworm. The digestive tract of an earthworm includes a muscular pharynx that sucks food in through the mouth. Food passes through the esophagus and is stored and moistened in the crop. The muscular gizzard, which contains small bits of sand and gravel, pulverizes the food. Digestion and absorption occur in the intestine, which has a dorsal fold, the typhlosole, that increases the surface area for nutrient absorption.
Esophagus
Crop
Gizzard
Intestine
Pharynx
Anus
Mouth
Typhlosole
Lumen of intestine
Foregut
Midgut
Hindgut
(b) Grasshopper. A grasshopper has several digestive chambers grouped into three main regions: a foregut, with an esophagus and crop; a midgut; and a hindgut. Food is moistened and stored in the crop, but most digestion occurs in the midgut. Gastric ceca, pouches extending from the midgut, absorb nutrients.
Esophagus
Rectum
Anus
Mouth
Gastric ceca
Crop
Esophagus
Gizzard
(c) Bird. Many birds have three separate chambers— the crop, stomach, and gizzard—where food is pulverized and churned before passing into the intestine. A bird’s crop and gizzard function very much like those of an earthworm. In most birds, chemical digestion and absorption of nutrients occur in the intestine.
Mouth
Intestine
Crop
Stomach
Anus

17. Complete digestive system or alimentary canal
Nematodes, annelids, mollusks, arthropods, echinoderms & chordates
Mouth Anus
Specialized compartments

18. The human digestive system
IIeum of small intestine
Duodenum of small intestine
Tongue
Cardiac orifice
Salivary glands
Oral cavity
Parotid gland
Mouth
Salivary glands
Sublingual gland
Pharynx
Submandibular gland
Esophagus
Esophagus
Pyloric sphincter
Liver
Stomach
Gall- bladder
Stomach
Ascending portion of large intestine
Gall- bladder
Small intestines
Liver
Pancreas
Pancreas
Large intestines
Small intestine
Rectum
Large intestine
Anus
Rectum
A schematic diagram of the human digestive system
Anus
Appendix
Cecum

19. Peristalsis – rhythmic waves of contraction and relaxation
Smooth Muscles pushes the food along the tract
Sphincters – Regulate the passage of material between chambers (Drawstring)

20.  From mouth to stomach: the swallowing reflex and esophageal peristalsis
The esophageal
sphincter relaxes,
allowing the
bolus to enter the
esophagus. 4
Epiglottis up
Esophagus
Epiglottis down
Bolus of food
Tongue
Epiglottis up
Glottis down and open
Pharynx
Esophageal sphincter contracted
Esophageal sphincter relaxed
Glottis
Esophageal sphincter contracted
Glottis up and closed
Larynx
After the food
has entered the
esophagus, the
larynx moves
downward and
opens the
breathing
passage. 5
Trachea
The larynx, the
upper part of the
respiratory tract,
moves upward and
tips the epiglottis
over the glottis,
preventing food
from entering the
trachea. 3
Relaxed muscles
To lungs
To stomach
Contracted muscles
When a person is not
swallowing, the esophageal
sphincter muscle is contracted,
the epiglottis is up, and the
glottis is open, allowing air
to flow through the trachea
to the lungs. 1
Relaxed muscles
Waves of muscular
contraction (peristalsis)
move the bolus down the esophagus to the stomach. 6
The swallowing
reflex is triggered
when a bolus of
food reaches the
pharynx. 2
Stomach

21. Accessory Glands
Salivary Glands – Deliver saliva with salivary amylase to begin chemical digestion
Pancreas – Digestive juices that mix with chyme in the small intestine
Liver – Produces bile. Bile salts aid in the break down of fats
Gall Bladder – Bile is stored here until needed

22. The stomach and its secretions
Pepsin (active enzyme)
HCl
Parietal cell
Chief cell
Stomach
Folds of epithelial tissue
Esophagus
Pyloric sphincter
Epithelium
Pepsinogen 3 2 1
Interior surface of stomach.
The interior surface of the stomach wall is highly folded and dotted with pits leading into tubular gastric glands.
Gastric gland. The gastric glands have three types of cells that secrete different components of the gastric juice: mucus cells, chief cells, and parietal cells.
Mucus cells secrete mucus,
which lubricates and protects
the cells lining the stomach.
Chief cells secrete pepsino-
gen, an inactive form of the
digestive enzyme pepsin.
Parietal cells secrete
hydrochloric acid (HCl).
Pepsinogen and HCI
are secreted into the
lumen of the stomach.
HCl converts
pepsinogen to pepsin.
Pepsin then activates
more pepsinogen,
starting a chain
reaction. Pepsin
begins the chemical
digestion of proteins.
5 µm
Small intestine
Cardiac orifice

23. Stomach Stores food and does preliminary digestion.
Coating of mucus to not self digest.
Mixing makes acid chyme. Every 20 seconds due to smooth muscles.
Pyloric sphincter squirts the acid chyme to the small intestines. 2 to 6 hours for a meal to empty.

24. The duodenum Liver Bile Acid chyme Stomach Pancreatic juice Pancreas
Intestinal juice
Duodenum of small intestine
Gall- bladder

25. Flowchart of enzymatic digestion in the human digestive system
Carbohydrate digestion
Protein digestion
Nucleic acid digestion
Fat digestion
Oral cavity,
pharynx,
esophagus
Polysaccharides
(starch, glycogen)
Disaccharides
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides,
maltose
Stomach
Proteins
Pepsin
Small polypeptides
Lumen of
small intes-
tine
Polysaccharides
Polypeptides
DNA, RNA
Fat globules (Insoluble in
water, fats aggregate as
globules.)
Pancreatic amylases
Pancreatic trypsin and
chymotrypsin (These proteases
cleave bonds adjacent to certain
amino acids.)
Pancreatic
nucleases
Bile salts
Maltose and other
disaccharides
Fat droplets (A coating of
bile salts prevents small drop-
lets from coalescing into
larger globules, increasing
exposure to lipase.)
Smaller
polypeptides
Nucleotides
Pancreatic carboxypeptidase
Pancreatic lipase
Amino acids
Glycerol, fatty
acids, glycerides
Epithelium
of small
intestine
(brush
border)
Small peptides
Nucleotidases
Disaccharidases
Dipeptidases, carboxypeptidase, and aminopeptidase (These proteases split
off one amino acid at a time, working from opposite ends of a polypeptide.)
Nucleosides
Nucleosidases
and
phosphatases
Monosaccharides
Amino acids
Nitrogenous bases,
sugars, phosphates

26. Small Intestine Absorption of nutrients takes place 6 meters
Duodenum - beginning of S.I.
Chyme
Villi – increases SA for more absorption

27. The structure of the small intestine
Microvilli (brush border)
Vein carrying blood to hepatic portal vessel
Blood capillaries
Epithelial cells
Muscle layers
Epithelial cells
Large circular folds
Lacteal
Villi
Key
Lymph vessel
Nutrient absorption
Villi
Intestinal wall

28. Large Intestine (Colon)
Recover water that has entered the alimentary canal
Feces (waste) becomes more solid as it moves through
Flora of bacteria – E. Coli
Colon bacteria secrete methane and hydrogen sulfide

29. 41.5 Modifications Teeth – Structural variation reflecting diets
Fangs – modified teeth & unhinged jaw

30. Dentition and diet Incisors Canines Molars (a) Carnivore Premolars
(b) Herbivore
(c) Omnivore

31. *Stomach – Expandable - Carnivores
*Length of alimentary canal – Herbivores longer
The digestive tracts of a carnivore (coyote) and herbivore (koala) compared
Stomach
Small intestine
Small intestine
Cecum
Colon (large
intestine)
Carnivore
Herbivore