1. Animal Nutrition Ch. 41 Lecture Objectives Importance of Food
Stages of Food Processing
Mammalian Alimentary Canal

2. 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

3. Figure 41.3
Figure 41.3 Obtaining essential nutrients from an unusual source

4. Four Stages of Food Processing

5. 1 INGESTION 2 DIGESTION 3 ABSORPTION 4 ELIMINATION
Figure 41.5
Mechanical digestion 1
INGESTION
Chemical digestion (enzymatic hydrolysis) 2
DIGESTION
Nutrient molecules enter body cells
Figure 41.5 The stages of food processing 3
ABSORPTION 4
ELIMINATION
Undigested material

6. Types of Feeders Suspension Feeders and Filter Feeders Substrate
Baleen
Substrate
Feeders
Fluid Feeders
Caterpillar
Feces
Bulk Feeders
Figure 41.6 Exploring: Four Main Feeding Mechanisms of Animals
Figure 41.6

7. 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)

8. Digestive enzymes are released from a gland cell. Food
Figure 41.7
Mouth
Tentacles 1
Digestive enzymes are released from a gland cell.
Food
Enzymes break food down into small particles. 2
Figure 41.7 Digestion in a hydra
Food particles are engulfed and digested in food vacuoles. 3
Epidermis
Gastrodermis

9. Alimentary Canals

10. Crop Gizzard Esophagus Intestine Pharynx Anus Mouth (a) Earthworm
Figure 41.8
Crop
Gizzard
Esophagus
Intestine
Pharynx
Anus
Mouth
(a) Earthworm
Foregut
Midgut
Hindgut
Rectum
Anus
Esophagus
Stomach
Figure 41.8 Alimentary canals
Gastric cecae
Crop
Mouth
Gizzard
(b) Grasshopper
Intestine
Mouth
Esophagus
Anus
Crop
(c) Bird

11. Duodenum of small intestine
Figure 41.9
Tongue
Oral cavity
Salivary glands
Mouth
Pharynx
Salivary glands
Esophagus
Esophagus
Gall- bladder
Stomach
Liver
Sphincter
Small intestine
Gall- bladder
Liver
Sphincter
Pancreas
Stomach
Large intestine
Figure 41.9 The human digestive system
Pancreas
Small intestine
Anus
Rectum
Large intestine
Duodenum of small intestine
Rectum
Anus

12. 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

13. 2. Esophagus & Peristalsis
Bolus of food
Tongue
Epiglottis up
Pharynx
Esophageal sphincter contracted
Glottis
Esophageal sphincter relaxed
Epiglottis down
Larynx
Trachea
Esophagus
Glottis up and closed
Figure Intersection of the human airway and digestive tract
To lungs
To stomach
(a) Trachea open
(b) Esophagus open
Figure 41.10

14. 3. Stomach & Gastric Juices (Mucus, HCl, Pepsinogen & Pepsin)
Figure 41.11
3. Stomach & Gastric Juices (Mucus, HCl, Pepsinogen & Pepsin)
Stomach
Gastric pit on the interior surface of stomach
Epithelium 3
Pepsinogen
Pepsin (active enzyme) 2
HCl
Gastric gland
Chief cell 1 H+
Figure The stomach and its secretions
Cl−
Mucous cell
Parietal cell
Chief cell
Parietal cell

15. 4. Small Intestine: Duodenum1
Stimulation Inhibition
Liver
Food
Gallbladder
Stomach
Gastric juices
Gastrin
Pancreas
Figure 41.20a Hormonal control of digestion (part 1: gastrin stimulation)
Duodenum of small intestine
Figure 41.20a

16. Figure 41.12 Chemical digestion in the human digestive system
CARBOHYDRATE DIGESTION
ORAL CAVITY, PHARYNX, ESOPHAGUS
Polysaccharides (starch, glycogen)
Disaccharides (sucrose, lactose)
Salivary amylase
Smaller polysaccharides
Maltose
PROTEIN DIGESTION
STOMACH
Proteins
Pepsin
Small polypeptides
NUCLEIC ACID DIGESTION
FAT DIGESTION
SMALL INTESTINE (enzymes from pancreas)
DNA, RNA
Fat (triglycerides)
Pancreatic amylases
Pancreatic trypsin and chymotrypsin
Pancreatic nucleases
Disaccharides
Nucleotides
Pancreatic lipase
Smaller polypeptides
Pancreatic carboxypeptidase
Figure Chemical digestion in the human digestive system
Glycerol, fatty acids, monoglycerides
Small peptides
SMALL INTESTINE (enzymes from intestinal epithelium)
Nucleotidases
Dipeptidases, carboxy- peptidase, and aminopeptidase
Nucleosides
Disaccharidases
Nucleosidases and phosphatases
Nitrogenous bases, sugars, phosphates
Monosaccharides
Amino acids

17. 5. Small Intestine: villi, microvilli & absorption
Microvilli (brush border) at apical (lumenal) surface
Vein carrying blood to liver
Villi
Epithelial cells
Lumen
Blood capillaries
Epithelial cells
(toward capillary)
Large circular folds
Muscle layers
Villi
Figure Nutrient absorption in the small intestine
Intestinal wall
Basal surface
Lacteal
Lymph vessel
Nutrient absorption
Figure 41.13

18. 6. Large Intestine Ascending portion of colon Small intestine Appendix
Figure Junction of the small and large intestines
Appendix
Cecum
Figure 41.15

19. 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

20. Colon (large intestine)
Figure 41.17
Small intestine
Small intestine
Stomach
Cecum
Figure The alimentary canals of a carnivore (coyote) and herbivore (koala)
Colon (large intestine)
Carnivore
Herbivore

21. Reticulum Rumen Esophagus 3 Intestine Omasum 2 Abomasum 4 1
Figure 41.19
Reticulum
Rumen
Esophagus 3
Intestine
Omasum 2
Abomasum 4
Figure Ruminant digestion 1