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CHAPTER 41 ANIMAL NUTRITION LEPTIN = apetite suppressor (hormone produced by fat cells) The four main stages of food processing are ingestion, digestion, absorption, and elimination Why Eat? C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy (ATP + heat) FUEL BIOSYNTHESIS ESSENTIAL NUTRIENTS Organic Macromolecules ATP (Cell Respiration) Everything you eat gets DIGESTED into glucose, amino acids, and glycerol + FUEL fatty acids Why Eat? These 3 digestion products BIOSYNTHESIS enter cell respiration ESSENTIAL (glycolysis and Kreb’s cycle) NUTRIENTS Products of cell respiration – CO2, NH3, H2O, ATP These end products can be used for cellular work (movement), generating heat, and BIOSYNTHESIS Excess gets converted to GLYCOGEN or FAT! Organic Macromolecules CO2, other simple compounds ATP Why Eat? Carbon Skeletons, and other simple products of cell respiration ATP FUEL BIOSYNTHESIS ESSENTIAL NUTRIENTS BIOSYNTHESIS = ANABOLIC PATHWAY Biosynthesis = Making of New Proteins, Carbohydrates, Fats, Nucleic Acids needed by the body using the energy and raw material derived from food How much energy do you get from food? Carbohydrates – 4 kcal/gm Proteins – 4 kcal/gm Fats – 9 kcal/gm Calorie = heat required to raise the temperature of water by 10c Kcal = 1000cal Cell Respiration = process that “burns” food Carbs = quick energy release Fats, proteins = slow to release energy What happens to excess carbs? Gets stored as glycogen in liver and muscle Too much carb? -Gets converted into fat!!!! Glycogen can be released quickly during exercise Disadvantge – less energy (4 kcal/gm) Fats – more energy (9kcal/gm), takes time to release How is glucose regulated? Insulin (produced by the Islets of Langerhans - in pancreas) = decreases blood sugar by ? Glucagon (pancreas) = increases blood sugar by ? 2 places to find glucose - blood or cells; stored as glycogen A) Glycogen synthesis in muscle and liver using free glucose in cells How is glucose regulated? B) Glycogen breakdown to release glucose into the cells C) Increased movement of glucose into blood from cells D) Decreased movement of glucose into blood from cells E) Increased uptake or movement of glucose from blood into cells F) Decreased uptake or movement of glucose from blood into cells G) Glucose utilization in cells - cell resp. H) Glucose synthesis in cells Insulin (produced by the Islets of Langerhans - in pancreas) = decreases blood sugar by A,D,E,G Glucagon (pancreas) = increases blood sugar by ? B,D,F,H Why Eat? FUEL BIOSYNTHESIS ESSENTIAL NUTRIENTS Essential nutrients – body cannot make it – so, it must be provided preassembled in the food. Example – Vitamins, essential amino acids, essential fatty acids, minerals + = An animal whose diet is missing one or more essential nutrients is said to be malnourished. Animals require 20 amino acids to make proteins. Essential amino acids must be obtained from food in prefabricated form. (eight) Protein Deficiency Kwashiorkar Essential fatty acids. – Certain unsaturated fatty acids, including linoleic acids required by humans. – Deficiencies are rare. Mahatma Gandhi once said, "Where ever flaxseeds become a regular food item among the people, there will be better health". Vitamins -organic molecules required in the diet in very small quantities (upto 100 mg) Fat Soluble Vitamins Water Soluble Vitamins A, D, E, K C, B, Niacin, Folic acid, Biotin Fat Soluble Vitamin Function Deficiency A Vision, maintain healthy skin Vision problems, dry skin D Absorption of Calcium and phosphorous = helps bone growth Rickets (bone deformities) E Antioxidant – maintains cell membrane K Blood clotting Clotting problems, Anemia Water Soluble Vitamin Function C Detoxification, antioxidant, collagen synthesis (gums) Deficiency Scurvy (skin, teeth, blood vessel degenration) B Coenzyme component B1 – Beriberi (1,2,6,12) –FAD, amino acid and (nerve disorder, nucleic acid anemia) metabolism, Minerals are simple inorganic nutrients, usually required in small amounts - from less than 1 mg to about 2,500 mg per day. Mineral Function Calcium Bone and tooth Retarded growth, formation, nerve and osteoporosis muscle function Hemoglobin component Anemia - cofactor Iron Sodium Acid- base balance, water balance, nerve Deficiency Too much – high blood pressure Feeder types: – Herbivores- eat autotrophs (plants, algae). – Carnivores - eat other animals. – Omnivores – eat animal and plant/algal matter Feeding mechanisms – Suspension-feeders that sift small food particles from the water.ex. Baleen whales, clam Fig. 41.6 Substrate-feeders live in or on their food source, eating their way through the food. – For example, maggots burrow into animal carcasses and leaf miners tunnel through the interior of leaves. Fig. 41.7 Deposit-feeders, like earthworms, eat their way through dirt or sediments and extract partially decayed organic material consumed along with the soil or sediments. Fluid-feeders make their living sucking nutrient-rich fluids from a living host and are often considered parasites. – Mosquitoes and leaches suck blood from animals. Most animals are bulk-feeders that eat relatively large pieces of food. Fig. 41.9 Human Digestive System Alimentary canal + accessory glands that secrete digestive juices into the canal through ducts. – Peristalsis: rhythmic wavespush food along. – Sphincters: muscular ringlike valves, regulate the passage of food – Accessory glands - salivary glands, the pancreas, the liver, and the gallbladder. –When does the lunch you had today complete its passage through your digestive system? • Mouth: Seconds • Esophagus: Seconds • Stomach: 2-6 hours • Small Intestine: 5-6 hrs. • Large Intestine: 12- 24 Hours TOTAL = 19 – 36 hrs!! Fig. 41.13 The journey begins …… Physical: chewing -Increases surface area of food Saliva - Moistens + Kills bacteria + Buffer Chemical digestion: Enzyme Salivary Amylase – Acts on “AMYLOSE” - long straings of glucose found in starch/glycogen (starch + glycogen) -> (smaller polysaccharides + maltose) Pharynx (throat) - opens to esophagus and the trachea (windpipe). – Epiglottis - cartilaginous flap prevents food going into the windpipe Epiglottitis Fig. 41.14 The stomach Muscular Organ – peristalisis chyme - mixture of gastric juice+food Gastric juice - glands Parietal cells - HCl – pH 2!! kills bacteria; converts pepsinogen -> pepsin (inactive)->(active) Chief cells - Pepsin – action = proteins -> polypeptides + amino acids Mucous cells - Mucous prevents eating away of stomach lining Pyloric Sphincterprevents back flow of food! Small intestine is the major organ of digestion and absorption 6 m long First section – duodenum LOTS OF ENZYMES FROM ACCESSORY GLANDS Pancreas makes – 1)pancreatic amylase - acts on polysachcharides -> tri, di saccharides; 2)bicarbonate - changes pH to make it basic so enzymes can act on the food; 3)trypsin, chymotrypsin - act on polypeptides ->tri & dipeptides , 4)lipase - acts on fats -> fatty acid and glycerol, 5)nucleases act on DNA and RNA -> nucleotides Liver makes bile; gall bladder – stores bile; bile emulsifies fats Lining of intestine – other enzymes (intestinal juice); convert to monomers . Fig. 41.18 Jejunum, ileum – sections of small intestine – absorption of nutrients into lymph/blood see notes in powerpoint slide for details Active transport –glucose, amino acid, vitamins Passive transport - fructose Hormones help regulate digestion Hormones released by wall of the stomach and duodenum Ensure that digestive secretions are present only when needed. – Stomach wall - hormone gastrin (stimulates gastric juice) – Duodenum – hormone Secritin (pancrease releases bicarbonate) – Duodenum – hormone Cholecystokinin (CCK)gallbladder releases bile Reclaiming water is a major function of the large intestine Cecum- very mall in humans - appendix Fig. 41.12 Fig. 41.12 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Structural adaptations of digestive systems are often associated with diet (1) Fig. 41.22