PHYSIOLOGY OF THE HEART Mechanical Aspects of Muscle Contraction.

Abstract

This communication attempts to summarise current concepts of the mechanical properties of heart muscle. Not considered here are the electrophysiological antecedents of contraction and the nervous control of the heart and circulation. The relationship of shortening of muscle to the tension it develops is shown in Figure 4. In this study the length of the muscle at the onset of stimulation was constant and the load to be moved was varied. The muscle shortened when the active tension became equal to the load and remained constant while the muscle shortened. The amount and duration as well as the velocity of shortening (dl/dtjust after the onset of shorten— ing) decreased as the load increased. Acknow1edgem: Figures 1, 2, 4, 5, 6 and 7 were taken from reference 1, and figures 3, 8 and 9 were taken from reference 2. The references were used extensively in compiling this communication.