of the system's functions progression depends completely on the duration of the system performance cycle. The longer the cycle period, the slower the system would transit from one level to another. The concepts of absolute and relative adiaphoria are directly associated with the concept of period and phase of system cycle. If, for example, the myocardium has not finished its "Systole-diastole" cycle, extraordinary (pre-term) impulse of rhythm pacemaker or extrasystolic impulse cannot force the ventricle to produce adequate stroke release/discharge. The value of stroke discharge may vary from zero to maximum possible, depending on at which phase of adiphoria period extrasystolic impulse occurs. If the actuating pulse falls on the 2nd and 3rd micro cycles, the myocardium would not react to them at all (absolute adiphoria), since information from the "X" receptor is not measured at the right time. Myocardium, following the contraction, would need, as any other cell would do following its excitation, some time to restore its energy potential (ATP accumulation) and ensure setting of all SFU in "startup" condition. If extraordinary impulse emerges at this time, the system's response might be dependent on the amount of ATP already accumulated or the degree in which actomyosin fibers of myocardium sarcomeres diverged/separated in order to join in the function again (relative adiphoria). Excitability of an unexcited cell is the highest. At the moment of its excitation excitability sharply falls to zero (all SFU in operation, 2nd micro cycle) - absolute adiphoria. Thereafter, if there is no subsequent excitation, the system would gradually restore its excitability, while passing through the phases of relative adiphoria up to initial or even higher level (super-excitability, which is not examined in this work) and then again to initial level. Therefore, pulse irregularity may be observed in patients with impaired cardial function, when sphygmic beats are force-wise uneven. Extreme manifestation of such irregularity is the so-called "Jackson's symptom"/pulse deficiency /, ie cardiac electric activity is shown on the electrocardiogram, but there is no its mechanical (haemodynamic) analogue on the sphygmogram and sphygmic beats are not felt when palpating the pulse. The main conclusions from all the above are as follows: any systems operate in cycles passing through micro cycles; any system goes through transition process; cycle period may differ in various systems depending on time constant of the system's reaction to the external impact/influence (in living systems - on the speed of biochemical reactions and the speed of command/actuating signals); irregularity of the system's cycle period depends on the presence of transition processes, consequently, to a certain degree on the force of external exposure/influence; irregularity of the system cycle period depends on overlapping of cycle periods of interacting systems; upon termi...
