Iron nerves
Can there be similarities between a nerve fiber and an iron rod? And whether! Under certain conditions, the two show striking similarities.
A nerve cell receives and processes stimuli from the environment or from the body. In turn, it conducts electrical signals via a long extension, the axon, to other cells, such as muscle fibers or glandular cells. The excitation conduction is based on the fact that there is an excess of negatively charged ions on the inside of the cell membrane and an excess of positively charged ones on its outside. The potential difference is between -30 and -150 millivolts (mV). When there is a stimulus, the permeability of the cell membrane to the ions changes. Positively charged ions (cations) then flow into the interior, which causes the membrane potential to decrease (from about -70 to -50 mV). Such a process is called depolarization. If the amount exceeds a threshold value, many more cations suddenly flow in and the charge on the membrane is briefly reversed – a so-called action potential is triggered. Ion currents then flow between the excited and the adjacent, non-excited area of the membrane both in the external medium and in the cell interior in order to balance the charges. Consequently, the membrane potential also changes there. When the threshold is reached, an action potential is generated again. In this way, the arousal moves on. The mechanism is shown in a highly simplified manner in the picture below on the left.
An iron rod immersed in a mixture of sulfuric acid solution and hydrogen peroxide reacts in a surprisingly similar way. Iron is actually a base metal, but in the electrolyte it is present in a specific form and thus behaves like a noble metal. Despite the acidic character of the solution, no evolution of hydrogen due to corrosion can be observed. This can be explained by the fact that iron is one of the so-called passivatable metals. It should actually corrode quickly under the given conditions…
