150 091 Lecture 2

150 091 Lecture 2 - Commentary on Lecture 2 Aug.28, 2008...

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Commentary on Lecture 2 Aug.28, 2008 The components of the macronutrients are interrelated. While glucose is the preferred energy source it is also used as the basis for synthesizing the 10 kinds of amino acids we are capable of making. The other 10 as we said last Tuesday, we need to obtain either directly from plants or get them from animals who in turn got them from plants. Any excess glucose is first used to rebuild the depleted stores of stored glucose (stored in muscle as glycogen). If there’s still an excess of glucose it’s converted to fatty acids which we store as fat in adipocytes Fat’s major role is as a secondary energy source. When glucose levels get low, your body use fat as an energy source. A certain few of the fatty acids are known today to be “essential” i.e., we can’t make them. These are used to make some very important molecules (and are not destined to be used for their energy content). There may very well be more of these important molecules yet to be discovered. Again the ultimate source of these essential fatty acids are plants. In periods of fasting or in starvation, glucose supplies are quickly depleted and your body begins using the fatty acids from the molecules of fat to make molecules that cells will accept as a substitute for glucose and use these as an energy source. Competitive athletes deplete their stores of glycogen rather rapidly and begin switching over to using stored fat. One of the reasons why distance runners are slender is that they use much of the fat their body stores in their sport. Your body’s need for glucose (other than for it’s energy) is met by starting to disassemble muscle protein into its constituent amino acids and those which we can make from glucose are reconverted into glucose. The “skin and bones”
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150 091 Lecture 2 - Commentary on Lecture 2 Aug.28, 2008...

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