Determination of the oxygen consumption of muscle The oxygen consumption of muscle may be determined in the intact body by taking a sample of the arterial blood before entering any given muscle and a sample of the venous blood issuing from the same muscle and determining the difference in oxygen content. By determining the volume of blood flowing through the muscle in a given time and knowing the weight of the muscle, the three factors necessary for calculating the oxygen consumption per gram of tissue per unit of time are available. Outside of the body, the oxygen consumption of surviving tissues may be determined by employing a micro-respirometer. This is a differential respirometer with two container flasks. The tissue under investigation is placed in flask (A) while flask (B) serves for the equilibration of gas volumes and pressures. If a few drops of dilute caustic potash are placed in the small cup in the center of the floor of flask (A) to absorb the carbon dioxide as it is formed and the tissue suspended in a small quantity of normal saline in the outer chamber, its oxygen consumption can be determined. To do this, the respirometer is properly sealed and immersed in a water bath controlled electrically to a constant temperature. By means of a special device the respirometer is gently shaken. After allowing sufficient time for the contents of the respirometer to reach the temperature of the bath, stopcocks 1 and 2 are turned so as to close the respirometer system from the outside air. As the oxygen is used up, the index drop of kerosene in horizontal capillary tube moves toward the tissue flask. This movement of the kerosene is proportional to one-half the oxygen consumed by the tissue provided the respirometer flasks are of exactly the same volume. Once the apparatus is accurately calibrated, the calculations are comparatively simple. In order to obtain the contemporaneous carbondioxide production, one need only to omit the potash. Under these conditions the volume of this gas given off replaces an equal volume of the oxygen consumed. The difference between the oxygen consumed with and without the potash is equal to the volume of carbon dioxide produced. The ratio between the oxygen consumption and carbon-dioxide production  may readily be obtained, that is, what is commonly termed the respiratory quotient, or in brief the R. Q. It will be shown later how the R. Q. of the individual tissues is related to the R. Q. of the organism as a whole.		Home Classes of levers Varieties of muscle Smooth muscle The blood supply to muscles The neurone Cardiac muscle On the nomenclature of skeletal muscles The nerve supply to muscles Structure of a skeletal muscle Central nervous system The reflex arc and reflex action Physiologic properties of muscle Mechanical Changes The effects of temperature on muscular contraction Muscle glycogen, its source and fate The reaction of muscles Oxygen consumption of muscle Determination of the oxygen consumption of muscle The viscosity factor in muscle and muscle efficiency Significance of the recovery heat Production of Electricity