The burden of food

1. The burden of food

2. Figure 5.2 The uses of energy by an animal

3. Effect of body size on weekly food requirement • Meadow- 30-g and 1900-Kg white rhino • Eat similar food • Vole eats about 6X its body weight to meet its energy needs • Rhino eats 1/3 of its body weight to meet its energy needs • Energy needs not proportional to their respective body size

4. Figure 5.6 The effect of body size on weekly food requirements

5. Figure 5.8 Weight-specific BMR as a function of body weight in various species

6. Figure 5.10 Metabolic rate and body weight are related linearly on log–log coordinates (Part 1)

7. Metabolic rate and body weight are related linearly on log-log coordinates • Metabolic rate and body weight are related alloemtrically among individuals of a single species

10. MR-body weight relation- physiological and ecological implications • Smaller animals breath more rapidly • Hearts of small animals beat faster for oxygen to be delivered at a greater rater per unit of body weight • Small-bodied species required food at a greater rate per unit of body weight

11. MR-body weight relation- physiological and ecological implications 2 • Population biomass per Km2- regular function of body size • Smaller animals eat food and breathe air at a greater rate • Small and large species process foreign chemicals differently • Smaller species more likely to accumulate environmental pollutants

12. Fundamentals of animal energetics cont’d • Animals use their absorbed chemical energy for 3 functions • Biosynthesis • Growth • Synthesis of organic materials that are exported from the body • Maintenance • Generation of external work

13. Fundamentals of animal energetics cont’d • Some energy is degraded to heat whenever one high-grade form of energy is transformed to another • Energy is not recycled • Animal takes in chemical-bond energy and put out heat, and external work

14. Units of measurement for energy and metabolic rates– calorie (cal) • Amount of heat needed to raise the temperature of 1 g of water by 1degree centigrade • Fundamental unit of measurement for energy in the SI system of units is the joule (J)

15. Summary: Metabolic rate • An animal’s MR is the rate at which it converts chemical energy into heat and external work • MR determines the amount of food an animal needs, and measures an animal’s intensity of existence • Rate of oxygen consumption is the most common measure of MR • MR can also be measured by direct calorimetery

16. Two themes in exercise physiology • Fatigue • Lessening of a muscle’s ability to generate peak forces and maintain power output • Depends on type and duration of exercise • Lactic acid accumulates • Acid-base disturbance • Inadequate muscle glucose • Accumulation of critical ions– Ca ++ • Overheating • Muscle fiber types

17. Figure 6.6 The fueling of intense but sustained muscular work in humans

18. Figure 6.9 The mechanisms of meeting the ATP costs of world-class competitive running

19. Metabolic depression in 2 invertebrates experiencing anoxia • Hypoxia or anoxia- low level of oxygen or an absence of oxygen • Respond to lack of oxygen by a drop in MR • Reduction in ATP needs • Metabolic depression depends on pH

20. Figure 6.11 Metabolic depression in two invertebrates experiencing anoxia (Part 1)

21. Figure 6.11 Metabolic depression in two invertebrates experiencing anoxia (Part 2)

22. Figure 6.12 Oxygen regulation and conformity (Part 1)

23. Figure 6.12 Oxygen regulation and conformity (Part 2)

24. Figure 6.12 Oxygen regulation and conformity (Part 3)

25. Oxygen regulation and conformity • Red circles mark ambient oxygen levels at which deaths occurred • Oxygen regulation- maintaining steady rate of aerobic catabolism regardless of oxygen level • Increase in breathing rate • Oxygen conformity- rate of oxygen consumption fall as environmental oxygen drops • Correlate with the types of habitats in which they live • Fish in slow-flowing water exhibits a much broader range of oxygen regulation

26. Oxygen consumption and physical performance at high altitudes • Human peak oxygen consumption and physical performance at high altitude • Decrease concentrations of oxygen • Cost of exercise remains the same • At 8000 meter minimal rates of climbing requires maximal O2 consumption

27. Box 6.3 The maximal rates of O2 consumption of human mountaineers at increasing altitudes

28. The interplay of aerobic and anaerobic catabolism during exercise • Cruising fish– steady-state aerobic catabolism • Can sustain for long periods • Use red swimming msucles • Sudden intense exertion • Use white swimming muscles • Accumulates lactic acid • Short period performance • Exception– insect flight muscle– always aerobic

29. Summary: Responses to impaired oxygen flux from the environment • Animals adapted to living without oxygen undergo metabolic depression when deprived of O2– lower MR • Reduce the rate the ATP must be supplied by catabolic mechanisms

30. Summary: Responses to impaired oxygen flux from the environment • Invertebrate anaerobes produce ATP by means of complex catabolic pathways • Organic products during anoxia are excreted as a way of avoiding end-product accumulation in their bodies • All vertebrates use anaerobic glycolysis to produce ATP in tissues deprived of O2 • Anoxia– strictly regional • CNS must retain adequate O2 supply

31. Summary: Responses to impaired oxygen flux from the environment • Turtles capable of total-body anoxia • Metabolic depression of the CNS • Become comatose • Goldfish and Crucian carp also can undergo total-body anoxia • Convert lactic acid to ethanol • Excrete ethanol to avoid end-product accumulation in their bodies • Maintain brain activity during anoxia to remain aware of their environment