Oxygen demand, determining factors

In this study most laboratories employed the chemical oxygen demand procedure for determining organic carbon employing a conversion factor of 0.375 to convert chemical oxygen demand to carbon content. 

Factors determining oxygen demand. The heart muscle cell consumes the most energy to generate contractile force. O2 demand rises with an increase in (1) heart rate, (2) contraction velocity, (3) systolic wall tension ( afterload ). The latter depends on ventricular volume and the systolic pressure needed to empty the ventricle. As peripheral resistance increases, aortic pressure rises, hence the resistance against which ventricular blood is ejected. O2 demand is lowered by 3-blockers and Ca-antago-nists, as well as by nitrates (p. 308). 

The major determinants of myocardial oxygen demand (MVO2) are heart rate (HR), contractility, and intramyocardial wall tension during systole. Wall tension is thought to be the most important factor. Because the consequences of IHD usually result from increased demand in the face of a fixed oxygen supply, alterations in MVO2 are important in producing ischemia and for interventions intended to alleviate it. 

Soil reduction can be described in both intensity and capacity terms. The intensity factor determines relative ease of reduction and is normally denoted by the redox potential (Eh). The capacity factor, however, denotes the amount of the redox system undergoing reduction and is equivalent to total amounts of labile carbon compounds or total energy sources that are utilized during microbial activity (best described in terms of its oxygen equivalent). In effect, two different soils with the same reduction intensity may differ with respect to the capacity factor because of variations in oxygen demand. 

The primary function of the heart is to deliver a sufficient volume of blood (oxygen and nutrients, etc.) to the tissues so that they may carry out their functions effectively. As the metabolic activity of a tissue varies, so will its need for blood. An important factor involved in meeting this demand is cardiac output (CO) or the volume of blood pumped into the aorta per minute. Cardiac output is determined by heart rate multiplied by stroke volume ... 

The factors responsible for the enormous variations in rate when bifunctional organic ligands mediate in electron-transfer reactions are by no means understood, but in the case of simple monocarboxylato-ligands the details of the adjacent-attack mechanism seem particularly well worked out. Sykes has reviewed the contribution that dinuclear complexes have played in this. In all simple monocarboxylato-com-plexes of the type (5) the point of Cr + attack is the carbonyl oxygen and its accessibility is determined by the size of R. The conformation (5) is more strongly demanded... 

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