Animal Nutri2on. Chapter 41. The Need to Feed. Need chemical energy, organic molecules, and essen2al nutrients

Transcription

1 Chapter 41 Animal Nutri2on BIOL 223 In general, animals fall into three categories: Herbivores Eat mainly autotrophs (plants and algae) Carnivores Eat other animals Omnivores Regularly consume animals as well as plants or algal maier The Need to Feed Need chemical energy, organic molecules, and essen2al nutrients An animal s diet provides chemical energy Animals converted into ATP need organic carbon and organic nitrogen to construct organic molecules Essen0al nutrients Required by cells must be obtained from dietary sources 1

2 Essen2al Nutrients There are four classes of essen2al nutrients: Essen2al amino acids Essen2al faiy acids Vitamins Minerals Animals Require 20 amino acids Can synthesize about half Essen0al amino acids Essen2al Amino Acids Must be obtained from food in preassembled form 9 in humans lacking causes malnutri2on called protein deficiency His2dine, Methionine, Threonine, Valine, Isoleucine, Lysine, Phenylalanine, Tryptophan, Leucine Essen2al Amino Acids Meat, eggs, and cheese Provide all the essen2al amino acids complete proteins Most plant proteins incomplete in amino acid makeup Not quinoa, hempseed, buckwheat, soy, spirulina (algae). Corn (maize) and other grains Essential amino acids for adults Methionine Valine Threonine Phenylalanine Leucine Isoleucine Beans and other legumes Tryptophan Lysine 2

3 Essen2al FaIy Acids Animals Can synthesize most of the faiy acids they need Essen0al fa7y acids unsaturated faiy acids must be obtained from diet Omega- 3, omega- 6 Deficiencies in faiy acids are rare Vitamins Vitamins Organic molecules required in the diet in small amounts vitamins essen2al to humans have been iden2fied Vitamin A (re2nol), Vitamin Bp (choline), Vitamin B1 (thiamin), Vitamin B2 (riboflavin, vitamin G), Vitamin B3 (niacin, vitamin P, vitamin PP), Vitamin B5 (pantothenic acid), Vitamin B6 (pyridoxine, pyridoxamine, or pyridoxal), Vitamin B7 (bio2n, vitamin H), Vitamin B9 (folic acid, folate, vitamin M), Vitamin B12 (cobalamin), Vitamin C (ascorbic acid), Vitamin D (ergocalciferol, or cholecalciferol), Vitamin E (tocopherol), Vitamin K (naphthoquinoids) Grouped into two categories fat- soluble and water- soluble Minerals Minerals Simple inorganic nutrients, usually required in small amounts Calcium (Ca), Chloride (Cl ), Chromium (Cr), Cobalt (Co), Copper (Cu), Iodine (I), Iron (Fe), Magnesium (Mg), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Phosphorus (P), Potassium (K), Selenium (Se), Sodium (Na), Sulfur (S), Zinc (Zn) 3

4 Undernourishment Dietary Deficiencies Diet with less chemical energy than the body requires Use up stored fat and carbohydrates Break down its own proteins Lose muscle mass Suffer protein deficiency of the brain Die or suffer irreversible damage Malnourishment Long- term absence from the diet of one or more essen2al nutrients can cause deformi2es, disease, and death can be corrected by changes to a diet Kwashiorkor Food processing Inges0on Is the act of ea2ng 4

5 Four Main Feeding Mechanisms Suspension Feeders Many aqua2c animals Sif small food par2cles from the water Baleen Humpback whale, a suspension feeder Four Main Feeding Mechanisms Substrate Feeders Animals that live in or on their food source Leaf miner caterpillar, a substrate feeder Caterpillar Feces Four Main Feeding Mechanisms Fluid Feeders Fluid feeders suck nutrient- rich fluid from a living host 5

6 Four Main Feeding Mechanisms Bulk Feeders Bulk feeders eat rela2vely large pieces of food Rock python, a bulk feeder Diges0on Food processing Process of breaking food down into molecules small enough to absorb Enzyma0c hydrolysis Splits bonds in molecules with the addi2on of water Pieces of food Small molecules Absorp0on Mechanical digestion Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Uptake of nutrients by body cells Elimina0on Passage of undigested material out of the diges2ve compartment Food Undigested material Ingestion Digestion Absorption Elimination Diges2ve Compartments Most animals Process food in specialized compartments Mouth, stomach(s), intes2ne(s), gastrovascular cavity reduce the risk of an animal diges2ng its own cells and 2ssues What type of 2ssue? 6

7 Intracellular Diges2on Intracellular diges0on Food par2cles engulfed by endocytosis digested within food vacuoles Extracellular Diges2on Extracellular diges0on Breakdown of food par2cles outside of cells Occurs in compartments that are con2nuous with the outside of the animal s body Extracellular Diges2on Gastrovascular cavity Tentacles Func2ons in both diges2on and distribu2on of nutrients Mouth Food Gastrovascular cavity In animals with simple body plans One opening Epidermis Gastrodermis Gastrodermis 7

8 Extracellular Diges2on Complete diges0ve tract or an alimentary canal More complex animals Crop Gizzard Intestine Pharynx Mouth Typhlosole Lumen of intestine Anus have a diges2ve tube with two openings (a) Earthworm Foregut Midgut Hindgut Rectum Anus mouth and an anus May have specialized regions Mouth Crop Gastric cecae (b) Grasshopper carry out diges2on and absorp2on in stepwise fashion Mouth Crop (c) Bird Stomach Gizzard Anus Intestine The mammalian diges2ve system alimentary canal and accessory glands Secrete diges2ve juices through ducts Mammalian accessory glands are Salivary glands Pancreas Liver Gallbladder Mammalian Diges2ve System Mammalian Diges2ve System Food is pushed along by peristalsis Rhythmic contrac2ons of muscles in the wall of alimentary canal Sphincters Muscular valves regulate the movement of material between compartments 8

9 Fig Tongue Oral cavity Sphincter Salivary glands Salivary glands Pharynx Mouth Liver Sphincter Ascending portion of large intestine Small intestine Gallbladder Pancreas Small intestine Large intestine Stomach Duodenum of small intestine Gallbladder Liver Pancreas Stomach Small intestine Large intestine Rectum Rectum Cecum Appendix Anus Anus A schematic diagram of the human digestive system The Oral Cavity, Pharynx, and Oral cavity First stage of diges2on Mechanical and chemical Salivary glands Deliver saliva to lubricate, digest food salivary amylase breakdown of carbohydrates The Oral Cavity, Pharynx, and Bolus Lump of ingested food Shaped by the tongue Pharynx Rear of the throat Junc2on that opens to both the esophagus and the trachea Trachea leads to the lungs 9

10 Conducts food from pharynx to stomach Swallowing The Oral Cavity, Pharynx, and by peristalsis causes the epigloks to block entry to the trachea bolus is guided past the larynx Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipe Tongue Pharynx Glottis Larynx Trachea Food Epiglottis up Esophageal sphincter contracted To To lungs stomach 10