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.
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.
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.
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
Stimulation of the sympathetic nervous system increases the
metabolic rates of essentially all of the tissues of the body.
GH can increase metabolic rate as much as 15 to 20 percent as a result of
direct stimulation of cellular metabolism.
Chemical reactions in the body increase when body temperature increases.