Animal Nutrition Ch. 41 Lecture Objectives Importance of Food Stages of Food Processing 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

Figure 41.3 Figure 41.3 Obtaining essential nutrients from an unusual source

Four Stages of Food Processing

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

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

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)

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

Alimentary Canals

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

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

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

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 41.10 Intersection of the human airway and digestive tract To lungs To stomach (a) Trachea open (b) Esophagus open Figure 41.10

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 41.11 The stomach and its secretions Cl− Mucous cell Parietal cell Chief cell Parietal cell

4. Small Intestine: Duodenum 1 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

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 41.12 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

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 41.13 Nutrient absorption in the small intestine Intestinal wall Basal surface Lacteal Lymph vessel Nutrient absorption Figure 41.13

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

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

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