Electrical Properties of Human Tissues and Cells: From Membrane Potential to Systemic Electrophysiology

Narrative review · Preprint · Version 1.0 · Not peer reviewed · Not submitted to a journal. A consolidated reference for the measured passive and active electrical properties of human cells and tissues, from the membrane to the whole body. Every value is reported with the species, preparation, method, frequency range and uncertainty that attached to it at the point of measurement, and every quantitative statement was verified against the indexed record of the source that reported it. Organising finding. The specific membrane capacitance of human neocortical layer 2/3 pyramidal neurons is approximately 0.5 µF/cm² — half the value its discoverers describe as the commonly accepted “universal” figure for biological membranes. The consequences are not a uniform factor of two and are not all in the same direction: because the membrane time constant is the measured quantity to which capacitance and resistance are jointly fitted, tau is approximately preserved while specific membrane resistance, input resistance and the dendritic space constant increase. The source’s own conclusion is that the low value enhances dendrite-to-soma charge transfer and axonal spike propagation. Contents. Membrane parameters and resting potential · excitable and non-excitable cells · passive tissue conductivity, resistivity and dielectric dispersion · skin · whole-body bioimpedance · ECG, EEG, EMG, EDA and their standards · measured applied fields in human cortex · endogenous fields in human tissue · a minimum specification for quoting a tissue electrical parameter · and a named list of the human measurements that do not currently exist. Three tables, three figures, 41 verified references. What this preprint does not do. It makes no therapeutic claim, evaluates no device, and describes no technology associated with the author. It computes no pooled estimate. Where only animal data exist — human skeletal muscle anisotropy, for example — it says so and declines to substitute them. Status. Version 1.0 of this manuscript was graded RED by an adversarial internal review and corrected; this is the corrected version, graded YELLOW. The change log is at §11.6 and lists twelve corrections, including a physics error in the original framing of the membrane-capacitance argument and four findings unfavourable to the manuscript that had been omitted from sources it otherwise relied on. Three full-text extractions remain outstanding and are listed at §11.3; the 95% confidence intervals for Table 2 are the priority item and could not be obtained because the source is not open access. Competing interests. The author is an electronics engineer, founder and Director of Rohera Healthcare & Technology Pvt. Ltd., Pune, India, and a named inventor on a patent family relating to electrical stimulation technology. He therefore holds a financial and intellectual interest in the field of applied bioelectricity. No device, product, patent or framework associated with the author or the company is described, evaluated, named or referred to anywhere in the manuscript. Full declaration, including the passages a sceptical reader should scrutinise, is in the Declarations section. Funding. Self-funded. This work received no external, grant or institutional funding; the costs were borne by the author and his companies, and the company provided no funding specific to this manuscript and had no role in its design, conduct, analysis, drafting or the decision to submit. Self-funding is declared here because it is itself a competing interest: no external sponsor reviewed, constrained or independently verified this work. Version 1.2 (this version). A second adversarial internal pass over version 1.1 found a further set of defects, all corrected here and listed in §11.7. The most serious: the abstract claimed an uncertainty column and a level of verification the tables do not deliver; the evidence-grading scheme used labels it had not defined and graded reviews and consensus documents as primary measurements; and §9’s headline comparison of endogenous wound fields to applied cortical fields omitted the three facts that weaken it. The manuscript now also states why §4 contains no parameter values, and records a second failed attempt to obtain the confidence intervals that Table 2 needs — no figure has been invented to fill that gap.