Summary
Highlights
Galvanic current is a continuous current with constant polarity, uninterrupted, and maintains a constant intensity. It requires a potential difference of 60-80 volts and an intensity of up to 200 milliamperes, though lower intensities are used in practical applications.
As a continuous current, it must be produced by elements that direct electrons in one direction and sense. This is achieved using batteries, rechargeable batteries, or AC rectifiers. Rectifiers convert alternating current by shifting the negative phase to the positive side, maintaining uniform polarity. Generators typically have a device to rectify AC and two terminals: positive and negative.
Galvanic current produces three main effects: electrothermal, electrochemical, and electrophysical. The electrothermal effect generates heat through Brownian motion, quantified by Joule's Law (0.24 * R * I^2 * t), where intensity and time are key variables. The electrochemical and electrophysical effects are often considered together due to their simultaneous and consecutive nature.
In an electrolytic cell with an anode and cathode, ions (like sodium and chlorine) in the human body are attracted to oppositely charged electrodes (chlorine to anode, sodium to cathode). This migration is called electroforesis. Once under the electrodes, electrolysis occurs, where chlorine forms an acidic reaction with water and metallic sodium forms an alkaline reaction with water. This process is governed by Faraday's first quantitative law, stating that the amount of chemical action is directly proportional to the current quantity.
Electroforesis involves two processes: cataforesis and anaforesis. In cataforesis, cations (positive ions) move towards the cathode (negative electrode). In anaforesis, anions (negative ions) move towards the anode (positive electrode).
Under each electrode, specific physiological reactions known as polar effects occur. Under the anode, there's an acidic reaction, low pH, acidic burns, coagulation, vasoconstriction, sedation, and decreased metabolic activity. Under the cathode, there's an alkaline reaction, high pH, alkaline burns, liquefaction, vasodilation, irritation, and increased metabolic activity. Anodal effects are beneficial for pathologies like tendinitis, while cathodal effects support processes like neurogenesis.