the external influence itself. It is positive because if there is a signal there is a reaction, if there is no signal, there is no reaction. Thus, the SFU control block reacts to the external influence. It can feel and detect/segregate specific signal of external influence from the multitude of other external influences and depending on the presence or absence of specific signal it may decide whether or not it should undertake its own action. Its own action is the inducement (stimulation) of the executive elements to operate. There exist uncontrollable and controllable SFU. The control block of uncontrollable SFU decides whether or not it should act, and it would make such decision only depending on the presence of the external influence. The control block of controllable SFU would also decide whether or not it should act depending on the presence of the external signal and in the presence of additional condition as well, ie the permission to perform this action which is communicated to its command entry point. The uncontrollable SFU has one entry point for the external influence and one outlet/exit point/for the result of action. The logic of work of such SFU is extremely simple: it would act if there is certain external influence (result of action), and no result of action is produced in the absence of external influence. For uncontrollable SFU the action regulator is the external influence itself. It has its own management which function is performed by the internal control block. But external management with such SFU is impossible. It would "decide" on its own whether or not it should act. That is why it is called uncontrollable. This decision would only depend on the presence of external influence. In the presence of external influence it would function and no external decision (not the influence) can change the internal decision of this SFU. The uncontrollable SFU is independent of external decisions. It will perform the action once it "made a decision". The example of uncontrollable SFU is, for instance, the nitroglycerine molecule (SFU for micro-explosion). If it is shaken (external influence is shaking) it will start to disintegrate, thereby releasing energy, and during this process nothing would stop its disintegration. The analogues of uncontrollable SFU in a living organism are sarcomeres, ligands of haemoglobin, etc. Once sarcomere starts to reduce, it would not stop until the reduction is finished. Once the ligand of haemoglobin starts capturing oxygen, it would not stop until the capturing process is finished. Unlike uncontrollable SFU, the controllable SFU have two entry points (one for the entry of external influence and another one for the entry of the command to the analyzer) and one outlet/exit point/for the result of action. The logic of work of controllable SFU is slightly different from that of the uncontrollable SFU. Such SFU will produce the result of action not only depending on the presence of ...
