Lecture 6 Sakai

Lecture 6 Sakai - Lecture 6 Lecture 20 20 September 2010...

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Unformatted text preview: Lecture 6 Lecture 20 20 September 2010 2010 Remarkable Remodeling of Structural and Functional Capacities of the Digestive Tract of an Episodic Feeder (Burmese python) Episodic Factorial Increase Remarkable Remodeling of Structural and Functional Capacities of the Digestive Tract of an Episodic Feeder (Burmese python) Episodic Factorial Increase See Feder, 2005 Reproduction Growth Allocation Trade-Offs: How much energy will be allocated to Production versus Respiration? How much energy will be allocated to Growth versus Reproduction? The Endocrine System has primary responsibility for metabolic regulation. metabolic Absorptive vs. Post-absorptive Absorptive Anabolic vs. Catabolic Insulin vs. Glucagon (and others) Insulin Glucagon (and Hour-to-hour regulation of energy hour metabolism depends mainly on the ratio of insulin to glucagon. ratio of glucagon Pathways of the Absorptive State “Absorptive State” GI tract is major energy source Follows a meal Anabolic: Protein synthesis. Glycogenesis. Lipogenesis. Uptake of glucose by liver. Excess glucose & amino acids are stored as fat. High insulin:glucagon ratio Pathways of the Post-Absorptive State Stored nutrients are Stored mobilized for use, with special emphasis on maintaining blood glucose. Preferential oxidation of fatty acids (and ketone bodies). Catabolic: Protein hydrolysis. Glycogenolysis. Lipolysis. Liver is source of glucose via glycogenolysis and gluconeogenesis. Low insulin:glucagon ratio Regulation of Food Consumption and Energy Balance over Longer Time Scales: Circannual Rhythms in GoldenMantled Ground Squirrels Regulation of Food Consumption and Energy Balance over Longer Time Scales The physiology of longdistance migration: extending the limits of endurance metabolism This short article is in the resource folder: “Recommended Readings” The physiology of long-distance migration This short article is in the resource folder: “Recommended Readings” Peroxisome proliferator-activated receptor Complex Integration of Environmental and Endogenous Information for Long-Term for Term Regulation of Food Consumption and Digestive Functions Digestive Why Do Animals Need Energy? Why The answer lies in the 2nd Law of Thermodynamics. Animals are open systems. They need energy to maintain themselves and to grow and reproduce in a highly ordered, thus thermodynamically unstable, state. Energy flow through animals is one-way. 342 W/m2 170 W/m2 170 2.7 x 1024 J/y See http://eosweb.larc.nasa.gov/EDDOCS/radiation_facts.html Fundamentals Fundamentals Forms of energy: Chemical Bond Electrical Mechanical Thermal Fundamentals Fundamentals Units of measurement: calories Glucose + 6O2 Energy 6CO2 + 6H2O 6CO PLUS 673 kcal/mol Fundamentals Fundamentals Units of measurement: Joule (SI unit) 1 cal = 4.186 J Energy Fundamentals Fundamentals Units of measurement: Watt (SI unit) 1W=1J/s Power Energy Budget Metabolic Rate Defined as the rate at which an animal consumes energy. 1. MR determines food requirements 2. MR provides a quantitative measure of the total activity of all physiological processes 3. MR measures how much useful energy an animal removes from its ecosystem Measurement of Metabolic Rate Direct Calorimetry Substrate + O2 ↔ CO2 + H2O + Heat C6H12O6 + 6O2 ↔ 6CO2 + 6H2O + 2874 kJ mole-1 Note stoichiometric relationships between O2 consumption, CO2 production, and heat production. Measurement of Metabolic Rate Direct & Indirect Calorimetry Substrate + O2 ↔ CO2 + H2O + Heat C6H12O6 + 6O2 ↔ 6CO2 + 6H2O + 2874 kJ mole-1 Note stoichiometric relationships between O2 consumption, CO2 production, and heat production. Indirect Calorimetry Respiratory Exchange Ratio: (CO2 produced) / (O2 consumed) When both of these quantities are known, the ratio can be calculated to indicate what type of metabolic fuel is being used. This allows a precise conversion of oxygen consumption (or carbon dioxide production) into units of energy or power. Field Metabolic Rate Isotope exchange can be used to measure metabolic rate in unrestrained, free-living animals. Doubly-labeled water: D218O or 3H218O is used to “label” total body water. 18O is lost as CO2 and H2O D (or 3H) is lost only as H2O The difference between the rate of loss of oxygen and the rate of loss of the hydrogen label is a measure of the rate of CO2 production, which is a measure of metabolic rate. Factors that Affect Metabolic Rate Factors that Affect Metabolic Rate Feeding Affects Metabolic Rate Burmese pythons. Secor & Diamond, 1998 Feeding Affects Metabolic Rate Specific Dynamic Action (SDA); see Figure 6.5 44X Fed human: 1.5X Running human: 18X Galloping racehorse: 45X 44X Basal Metabolic Rate (BMR) Standard Metabolic Rate (SMR) These are standardized measurements to facilitate comparisons among individuals and species. BMR: standardized measure of metabolic rate in endothermic homeotherms Required conditions include: Thermoneutral zone (no metabolic response to external temperature) Fasting (no SDA) Resting (no activity) Non-reproductive Basal Metabolic Rate (BMR) Standard Metabolic Rate (SMR) These are standardized measurements to facilitate comparisons among individuals and species. SMR: standardized measure of metabolic rate in ectotherms Required conditions include: Fasting (no SDA) Resting (no activity) Non-reproductive SMR is temperature-specific Factors that Affect Metabolic Rate ...
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This note was uploaded on 04/03/2011 for the course BIO 704:360 taught by Professor John-alder during the Fall '11 term at Rutgers.

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