NUTR 4210 Lecture Notes - Lecture 1: Stroke Volume, Phosphorylase, Oxidative Phosphorylation
6 Dec 2017
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Document Summary
Heat production is used as a measure of energy expenditure. Direct calorimetry: measures the heat a person generates in a sealed chamber. Heat energy is measured as a change in temperature. Amount of heat produced is proportional to amount of energy expended. Disadvantages: v. expensive, con ned space, direct assessment isn"t practical or feasible; used mostly for research purposes. Indirect calorimetry: method of estimating energy expenditure by measuring changes in oxygen consumption and/or co2 production. As energy expenditure , o2 consumption and co2 production by aerobic energy system increases proportionately. Open circuit spirometry: ambient room air inhaled, use of metabolic cart. Ow meter to measure amount of air breathed, analyzers measure % of o2 & co2 in air, computer for calculations. Lying down in supine position, minimal energy expenditure prior, room w/ controlled temperature, relaxed as possible in post-absorptive state. Disadvantages: hyperventilate = inaccurate, may not be air tight, mask comfort.
