2.12.10 - Animal physiology materials and energy budgets...

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Organisms are enormously complex molecular assemblies that must exchange energy and materials with the environment: open systems: no exchange = no life Some exchanges are slow: atoms in the DNA of a brain cell Some are fast: half-life of water is days in a human, minutes in a small fish ALL must be carefully balanced! Energy and material exchange is a set of budgets : gains: heat, food, water, oxygen losses: heat, water, CO 2 , urine, feces Animal physiology is largely about how these exchanges are managed. Animal physiology: materials and energy budgets IN: OUT: food oxygen water heat wastes CO 2 water heat Food eaten: 2-3 tons Oxygen used: 2 tons Water intake: 6-10 tons Heat produced: 7 million kilocalories Clearly, a balanced budget is critical! Partial ‘bookkeeping’ for an adult woman (.05 tons) over 10 years: Animal physiology: materials and energy budgets We focus on energy metabolism and the energy budget Measures both energy and materials: Food can be used to produce energy (by using chemical potential energy) or to build tissue Energy metabolism (metabolic rate) : the sum total of all biochemical energy ‘transactions’ at a given time… = rate of production and utilization of ATP Average human contains about 50 grams of ATP at a given time… but makes and uses about 40 kilograms of ATP per day! About 5.5 X 10 20 ATP molecules -- 0.5 g -- per second. For most animals, budgets are not in balance only during: growth (change in body size or storage of fat) reproduction (production of offspring) Animal physiology: materials and energy budgets Metabolism (metabolic rate) : the rate of production and utilization of ATP. Cellular respiration is the source of most ATP for animals Glycolysis glucose Electron transport & Oxidative phosphorylation Krebs cycle no O 2 O 2 present ATP net 2 ATP ATP net 38 ATP 6 CO 2 6 H 2 0 HEAT Animal energy budgets 2 pyruvate (lactate) HEAT
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Metabolism (metabolic rate) : the rate of production and utilization of ATP. Cellular respiration is the source of most ATP for animals Glycolysis fats Proteins (amino acids) NH 3 Electron transport & Oxidative phosphorylation Krebs cycle ATP CO 2 H 2 0 HEAT Animal energy budgets Measuring metabolism heat production: cellular respiration is (at most) ~40% efficient; the rest of the chemical potential energy in fuels is lost as heat.
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2.12.10 - Animal physiology materials and energy budgets...

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