1. Animal nutrition
Chapter 41

3. Function 1. Digestion 2. Absorption of nutrients/water 3. Elimination
Energy
Growth
3. Elimination

4. 1 INGESTION 2 DIGESTION 3 ABSORPTION 4 ELIMINATION
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

5. Heterotrophs

6. Intracellular digestion

7. Extracellular digestion

8. Extracellular digestion

9. Figure 41.1 How does a crab help an otter make fur?

10. Figure 41.9 Variation in alimentary canals
Crop
Gizzard
Esophagus
Intestine
Pharynx
Anus
Mouth
Typhlosole
Lumen of intestine
(a) Earthworm
Foregut
Midgut
Hindgut
Esophagus
Rectum
Anus
Crop
Mouth
Gastric cecae
Figure 41.9 Variation in alimentary canals
(b) Grasshopper
Stomach
Gizzard
Intestine
Mouth
Esophagus
Crop
Anus
(c) Bird

11. Digestive system

12. General structure Gastrointestinal tract (tube)
Mucosa: inner layer (epithelial)
Submucosa: connective
Muscularis: 2 layers of muscle
Serosa: outer layer (connective)
Plexues: nerves located in the submucosa

13. Digestive organs Mouth Pharynx Esophagus Stomach
Small intestine (duodenum, jejunum, ileum)
Large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid, rectum, anus)

14. Digestive organs
Accessory organs
Liver
Gallbladder
Pancreas

15. Digestion Mouth Teeth Gizzard (in birds to help grind food)
Salivary glands
Secrete saliva
Amylase (enzyme to breakdown starch)

16. Mouth

17. Salivary glands

18. Digestion Chew or mastication Tongue pushes food Pharynx
Epiglottis closes
Esophagus

19. Pharynx

20. Esophagus Esophagus Muscular tube Connects pharynx to stomach
Peristalsis:
Rhythmic movement of muscle contractions
Moves food along
Esophageal sphincter:
End of esophagus keeps food in stomach

21. Stomach Mucosa lining (epithelial) Parietal cells Secrete H + Cl ions
Chief cells
Secrete pepsinogen
Pepsinogen is converted to pepsin
Digests proteins

22. Stomach Gastric juices: HCl, pepsinogen & mucus pH=2 Chyme:
Mixture of partially digested food

23. Stomach

24. Stomach

25. Small intestine Chyme Leaves stomach via pyloric sphincter Duodenum
Digestive enzymes from pancreas
Bile from liver & gallbladder
Most digestion occurs in the duodenum & jejunum

26. Intestines

27. Small intestine

28. Small intestines Villi along intestine epithelium Microvilli
“brush border”
Aids in absorption
Secretes enzymes
Break disaccharides (sucrose, lactose)

29. Small intestine

30. Accessory organs

31. Accessory organs Pancreas Secretes fluids via pancreatic duct
Exocrine system
Trypsin & chymotrypsin (proteases)
Amylase (starch)
Lipase (fats)
Bicarbonate (neutralizes HCl)
Endocrine (insulin and glucagon)

32. Accessory organs Liver Secretes bile
Contains bile pigments & bile salts
Bile pigments are waste from break down of RBC
Eliminated

33. Accessory organs Bile salts Emulsify the fats Bile made in liver
Stored in gall bladder
Released when eat fatty meal
Gallstones can block release

34. Small intestines
Monosaccharides, aa are transported to the blood capillaries
Hepatic portal vein
Liver
Heart
Transported to body

35. Small intestines Fatty acids & monoglycerides Villi Triglycerides
Chylomicrons: (triglyceride & protein coat)
Lymph system

36. Microvilli (brush border) at apical (lumenal) surface
Fig b
Microvilli (brush border) at apical (lumenal) surface
Lumen
Blood capillaries
Epithelial cells
Basal surface
Epithelial cells
Lacteal
Figure The structure of the small intestine
Lymph vessel
Villi
Key
Nutrient absorption

37. Lumen of small intestine Triglycerides Fatty acids Monoglycerides
Fig
Lumen of small
intestine
Triglycerides
Fatty acids
Monoglycerides
Epithelial cell
Triglycerides
Phospholipids, cholesterol, and proteins
Figure Absorption of fats
Chylomicron
Lacteal

38. Essential nutrients Carbohydrate digestion Protein digestion
Nucleic acid digestion
Fat digestion
Oral cavity, pharynx, esophagus
Polysaccharides
Disaccharides
(starch, glycogen)
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides, maltose
Stomach
Proteins
Pepsin
Small polypeptides
Lumen of small intes- tine
Polysaccharides
Polypeptides
DNA, RNA
Fat globules
Pancreatic amylases
Pancreatic trypsin and chymotrypsin
Pancreatic nucleases
Bile salts
Maltose and other disaccharides
Fat droplets
Nucleotides
Smaller polypeptides
Pancreatic lipase
Pancreatic carboxypeptidase
Glycerol, fatty acids, monoglycerides
Amino acids
Epithelium of small intestine (brush border)
Small peptides
Nucleotidases
Nucleosides
Disaccharidases
Dipeptidases, carboxypeptidase, and aminopeptidase
Nucleosidases and phosphatases
Monosaccharides
Amino acids
Nitrogenous bases, sugars, phosphates

39. Large intestines Absorbs water Absorbs vitamin K Concentrates wastes
E. coli
Feces
Cloaca
Combines feces & urine wastes in some animals

40. Large intestine

41. Large intestine

42. Absorbed food (except lipids) Absorbed water Mouth Stomach Lipids
Veins to heart
Hepatic portal vein
Lymphatic system
Liver
Absorbed food (except lipids)
Absorbed water
Mouth
Stomach
Lipids
Esophagus
Figure 41.UN04 Summary of key concepts: mammalian digestive organs
Small intestine
Anus
Secretions from salivary glands
Secretions from gastric glands
Secretions from liver
Large intestine
Rectum
Secretions from pancreas

43. Food BMR Basal metabolic rate Obesity Heart disease, diabetes, stroke
Anorexia, Bulimia

44. Essential nutrients Essential aa Minerals Vitamins
A, B-complex, C, D, E, K
Scurvy, rickets, pernicious anemia, bleeding

45. Figure 41.3 Obtaining essential nutrients from an unusual source

46. Abnormalities Ulcers H. pylori Bacteria Treated with antibiotics
Reflux:
Gastric juices go backwards to esophagus

47. Hiatal hernia

48. Pyloric Stenosis

49. Colon Cancer

50. Jaundice