Cathode

Cathode, electrode, connected with the negative pole of a battery. If two metal plates are immersed in a liquid, connected with the poles of a battery, then the difference between the cathode and anode will manifest itself as follows: if the plates from which the electrodes are made are unchangeable, for example platinum, and the electrodes are immersed in weakly acidified and therefore well-conducting water, then at the C. (negative electrode) positively charged hydrogen ions are released; when current passes through electrolytes, positive cations (metals) are released at the C. The cathode and anode behave differently in vacuum tubes (Geissler, cathode, X-ray). When constant current passes through living tissues, the phenomena occurring near the anode and C. (extrapolar sections) are not the same. With such polar action of current, the cathode acts as an agent causing increased excitability of tissues, while the anode acts as an element causing a decrease in this excitability (see Bioelectric currents, Animal electricity, Ionic theory of excitation).