Chapter 41 Animal Nutrition

1. Chapter 41 Animal Nutrition

2. Nutritional requirements • Undernourishment: caloric deficiency • Overnourishment (obesity): excessive food intake • Malnourishment: essential nutrient deficiency • Essential nutrients: materials that must be obtained in preassembled form • Essential amino acids: the 8-10 amino acids that must be obtained in the diet (Arginine, Histidine – Infants) • Essential fatty acids: unsaturated fatty acids • Vitamins: organic coenzymes • Minerals: inorganic cofactors

3. Food types/feeding mechanisms • Opportunistic • Herbivore: eat autotrophs • Carnivore: eat other animals • Omnivore: both • Feeding Adaptations • Suspension-feeders: sift food from water (baleen whale) • Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) • Fluid-feeders: suck fluids from a host (mosquito) • Bulk-feeders: eat large pieces of food (most animals)

4. Overview of food processing • 1-Ingestion: act of eating • 2-Digestion: process of food break down • enzymatic hydrolysis • intracellular: breakdown within cells (sponges) • extracellular: breakdown outside cells (most animals) • alimentary canals (digestive tract) • 3- Absorption: cells take up small molecules • 4- Elimination: removal of undigested material

5. Mammalian digestion • Peristalsis: rhythmic waves of contraction by smooth muscle • Sphincters: ring-like valves that regulate passage of material • Accessory glands: salivary glands; pancreas; liver; gall bladder

6. Mammalian digestion • Oral cavity •salivary amylase •bolus • Pharynx •epiglottis • Esophagus • Stomach •gastric juice •pepsin/pepsinogen (HCl) •acid chyme •pyloric sphincter

7. When blood glucose level rises, a gland called the pancreas secretes insulin, a hormone, into the blood. 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. STIMULUS: Blood glucose level rises after eating. 1 2 3 4 Homeostasis: 90 mg glucose/ 100 mL blood STIMULUS: Blood glucose level drops below set point. When blood glucose level drops, the pancreas secretes the hormone glucagon, which opposes the effect of insulin. Figure 41.3 Homeostatic regulationof cellular fuel Glucagon promotes the breakdown of glycogen in the liver and there lease of Glucose into the blood,increasing blood glucose level.

8. Liver Bile Gall-bladder Stomach Acid chyme Intestinaljuice Pancreatic juice Pancreas Duodenum of small intestine Figure 41.19 The duodenum

9. Hormonal Action: Gastrin food---> stomach wall ---> gastric juice Enterogastrones (duodenum) 1-Secretin acidic chyme---> pancreas to release bicarbonate 2-Cholecystokinin (CCK) amino/fatty acids---> pancreas to release enzymes and gall bladder to release bile Large intestine (colon) Cecum Appendix Feces Rectum/anus Mammalian digestion

10. Enterogastrone secreted by the duodenum inhibits peristalsis and acid secretion by the stomach, thereby slowing digestion when acid chyme rich in fats enters the duodenum. Liver Entero- gastrone Gall- bladder Gastrin Gastrin from the stomach recirculates via the bloodstream back to the stomach, where it stimulates the production of gastric juices. CCK Stomach Amino acids or fatty acids in the duodenum trigger the release of cholecystokinin (CCK), which stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder. Pancreas Secretin Duodenum Secreted by the duodenum, secretinstimulates the pancreas to release sodium bicarbonate, which neutralizes acid chyme from the stomach. CCK Key Stimulation Inhibition Figure 41.22 Hormonal control of digestion

11. Mammalian digestion • Small intestine •duodenum •bile • Intestinal digestion: a-carbohydrate b-protein c- nucleic acid d-fat

12. Mammalian digestion • Villi / microvilli • Lacteal (lymphatic) • Chylomicrons (fats mixed with cholesterol) • Hepatic portal vessel

13. Evolutionary adaptations • Dentition: an animal’s assortment of teeth • Digestive system length • Symbiosis • Ruminants