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Energy and Metabolism

Energy and Metabolism. Energy. the capacity of a system to do work Energy is obtained by the food we eat Primary nutrients: Carbohydrates Lipids Proteins Vitamins Minerals water. Metabolism.

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Energy and Metabolism

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  1. Energy and Metabolism

  2. Energy • the capacity of a system to do work • Energy is obtained by the food we eat • Primary nutrients: • Carbohydrates • Lipids • Proteins • Vitamins • Minerals • water

  3. Metabolism • The set of chemical reactions that occur in living organisms that are necessary to maintain life • 2 types of metabolism • Catabolism: metabolism that breaks down larger molecules into smaller subunits • Anabolism: metabolism that use energy to produce larger molecules from smaller subunits • Metabolic rate is related to body temperature as heat is necessary for the activation energy of reactions

  4. Ectotherms • Ecto = outside; therm = heat • Organisms that receive their necessary body heat from external sources

  5. Endotherms • Endo = inside; therm= heat • Organisms that create their heat energy by metabolic reactions

  6. Factors affecting metabolism • Body size: larger=more energy • Physical activity: more active=more energy • Sex: males need more energy than females • Age: rate slows with age • Genetics

  7. BMR – basal metabolic rate • Basal – essentially the baseline value for a measured physiological factor • Measured in Joules (standard unit of energy) Females: BMR = [655 + (9.6 x mass) + (1.8 x height) - (4.7 x age)] x 4.18 Males: BMR = [66 + (13.7 x mass) + (5.0 x height) - (6.8 x age)] x 4.18

  8. Factoring in Exercise • Little to no BMR x1.2 • Light (1-3 times/week) BMR x1.375 • Moderate (3-5 times/week) BMR x1.55 • Vigorous (6-7 times/week) BMR x1.725 • Extreme BMR x1.9

  9. Relating BMR to food • Converting to Calories • 1 Calorie = 4.18 KJ • So . . . If a person calculates their BMR to be 12 000 kJ then . . . 12 000 ÷ 4.18 = 2 871 C/day

  10. Applying BMR • Let’s look a little deeper into metabolism: • A person calculates they need 2 500 C per day • They consume 3 000 C and need to know how much exercise is needed to burn off the extra 500 calories 500 C = 2090 kJ . . . If running burns 37.5 kJ/kg/h it would take approx. 0.9 hours to burn the energy Or . . . 3 hours of walking would also do the trick (refer to pg 399 for more info)

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