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The burden of food anphys-opener-05-0.jpg
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Figure 5.2 The uses of energy by an animal
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Figure 5.5 Specific dynamic action (Part 2)
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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
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Figure 5.6 The effect of body size on weekly food requirements
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Figure 5.8 Weight-specific BMR as a function of body weight in various species
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Figure 5.10 Metabolic rate and body weight are related linearly on log–log coordinates (Part 1)
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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
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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
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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
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Fundamentals of Animal Energetics
Forms of energy vary in their capacity to do physiological work Chemical-bond energy is totipotent for animals Electrical and mechanical energy can do certain types of physiological work Heat cannot perform any physiological work
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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
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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
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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)
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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
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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
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Figure 6.6 The fueling of intense but sustained muscular work in humans
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Figure 6.9 The mechanisms of meeting the ATP costs of world-class competitive running
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Muscle fiber types Slow oxidative Fast-glycolytic
Makes ATP by aerobic catabolism (AC) High levels of key enzymes specific to AC High concentration of mitochondria High in myoglobin Fast-glycolytic Makes ATP by anaerobically High levels of anaerobic glycolysis enzymes Sparse mitochondria, low myoglobin
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Figure 6.10 Two top athletes who differ in the fiber composition of their thigh muscles (Part 1)
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Figure 6.10 Two top athletes who differ in the fiber composition of their thigh muscles (Part 2)
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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
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Figure 6.11 Metabolic depression in two invertebrates experiencing anoxia (Part 1)
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Figure 6.11 Metabolic depression in two invertebrates experiencing anoxia (Part 2)
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Figure 6.12 Oxygen regulation and conformity (Part 1)
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Figure 6.12 Oxygen regulation and conformity (Part 2)
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Figure 6.12 Oxygen regulation and conformity (Part 3)
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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
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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
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Box 6.3 The maximal rates of O2 consumption of human mountaineers at increasing altitudes
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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
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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
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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
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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
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