Metabolism w11 worksheet.docx - W11 Worksheet Metabolism...

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W11 Worksheet: Metabolism Lab Follow the instructions below very carefully. Many of the items in this assignment require reading, or videos, or something else to do. Each question has either a text box that can be filled out or a box that can be checked to show completion. Be sure to type out your answers completely and expand the text boxes if you need the additional space. Question 1 --- 2 points Basic Metabolic Rate Body metabolism simply means all of the chemical reactions taking place in the cells of the body and the metabolic rate is normally expressed in terms of the rate of heat liberation during those chemical reactions. Metabolic rate is expressed as kilocalories (Cal) per hour. Since direct measurement of heat production from the whole body involves very cumbersome and expensive apparatus, this method has been reserved to check the validity of indirect methods. Indirect methods use measurement of oxygen consumption as an indicator of heat production. The amount of heat produced when one liter of oxygen is metabolized depends on what type of nutrient is being utilized. When one liter of oxygen is metabolized with glucose, 5.01 Cal of energy are released; when metabolized with starches, 5.06 Cal are released; when metabolized with fat, 4.7 Cal, and when metabolized with protein 4.6 Cal. It has been determined that for the average diet, approximately 4.825 Cal are released per liter of oxygen consumed. Using this value, we can compute a relatively accurate estimate of the metabolic rate. Metabolic rate is affected by any factor that increases chemical activity in the cells. Listed below are some of the factors that are known to have an effect on metabolic rate. 1. Exercise: Exercise causes by far the most dramatic changes in metabolic rate. In this lab procedure we will determine the effects of exercise on metabolic rate. 2. Age: The metabolic rate of a newborn child in relation to his body surface area is almost twice that of an aged person. Metabolic rate drops rapidly for about the first 20 years of life and then continues to slowly decline for the rest of a person’s life. The high metabolic rate in children results from both high rates of cellular reactions as well as from rapid synthesis of cellular materials and growth of the body. 3. Thyroid Hormones: These hormones control the rate of activity of almost all the chemical reactions in the body. Hypo and hyper secretion of thyroid hormones have major effects on metabolic rate. 4. Sympathetic stimulation: Stimulation of the sympathetic nervous system increases the metabolic rates of essentially all of the tissues of the body. 5. Growth Hormone: GH can increase metabolic rate as much as 15 to 20 percent as a result of direct stimulation of cellular metabolism. 6. Fever: Chemical reactions in the body increase when body temperature increases.

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