Functional Properties of the Heart

In the preceding chapter the overall behavior of the heart has been considered as it is reflected in the periodical alternation of diastole and systole and of filling and ejection of the atria and ventricles. This description of the cardiac cycle included the accompanying changes in pressure and volume of the cardiac chambers. However, a deeper comprehension of cardiac function has to take into account some specific properties of the myocardial tissue as opposed to other types of muscle, mainly skeletal muscle, and the transformation of wall tension into pressure by the hollow muscular organ. Moreover, the compensatory changes in the heart in response to different degrees of filling (preload) or of resistance against ejection (afterload) are also discussed in this chapter, as are regulatory influences on myocardial contractility.