This section recalls dichotomies discussed in section 2.2.4 from the viewpoint of electricity. Electricity is one of the fundamental disciplines of classical physics. It operates with concepts such as charge, current, voltage; furthermore, their spatial or temporal change described by their gradients (spatial or temporal derivatives). Physical and biological electricity are similar, but not identical. The former was already an established discipline when the latter started to discover that biological objects also show signs of electric processes occurring inside them. Of course, the already available concepts, laws, measurement devices and procedures were taken over, and based on the resemblance between those two kinds of electricities, their identity was and is assumed. The laws of physical electricity, in most cases, describe also biological electricity to some measure. However, in some cases, there are drastic differences between them. Not considering those differences leads to misunderstandings and wrong conclusions.
Physical electricity operates with concepts of ideal (voltage or current) generators, ideal (that is single-substance) charge carriers, and discrete components, connected by ideal conducting wires. The wires are passive components, just connect the discrete components and the electric phenomena happen in the discrete elements, with one idealized feature. Physical electricity inherited the Newtonian picture that everything happens simultaneously and it applies a hybrid picture. It considers that no delay exists on the connecting wires, although charge passes in the current. The current is defined as temporal change of charge, but it is explicitly considered only in the slighty non-ordinary phenomena capacitance, inductance and impedance; it is considered as instant in the phenomenon called resistance. In biological electricity, neither of the above disciplinary concepts can be interpreted in unchanged form, they must be reinterpreted. The charges are moved not necessarily by an electric field, but their movement is interpreted as current (and, simultanously, as mass transport) furthermore, that movement creates change in the potential (as well as in the concentration), due to the limited resources. Since the charge carriers are slow, local, instead of global, potentials must be used. The integral forms of laws of electricity are not valid in the form we used to in physical electricity. The charge (and mass) conservation are valid only in the global sense; while in classical physics, with its concept ’instant interaction’, local and global coincide. Fortunately, physiology inherited the ambititon from physics to measure its subject, together with the measurement methodologies and devices. Unfortunately, as we detail in section 2.3, measuring living matter (because of its ”special construction”) requires at least considerable care, sometimes different methodologies and appropriate interpretation; including the understanding of the special kind of electricity it applies.
The different charge transmission mechanism introduces another important difference, the relation to thermodynamics. In physical electricity, the medium is a solid, where the electrons heavily interact with the nodes in the solid (forming a kind of ’electron cloud’). In a good approximation, they are not comprising free and independent particles, so their phenomena are not related to thermodynamics. The ions, in contrast, are nearly independent, so they would be described by thermodynamics. However, they are simultanously also charged particles, so they are governed also by the laws of electricity. These two circumstances together represent a case which is not belonging to either dicipline. More precisely, neither of the two disciplines can describe the phenomena without the other. The case is somewhat similar to the case when an ion moves in simultanously applied electric and magnetic fields, and it is considerably different in that the thermodynamic interaction also represents a mass transport, inseparably, so the driving force is the sum of the thermal and electric gradients. The real complication and difference is, however, that the interactions have different speeds. However, it is not a different physics (”or whatnot”). It is only using different laws for the different environment from the same first principles.