Electrical and Magnetic Properties of Living Tissues

Vocabulary flashcards reviewing the electrical and magnetic properties of living tissues, dielectric permittivity, conductivity across body media, frequency dispersions, and magnetic classifications.

Electrical Conductivity of Biological Tissues

A parameter that characterizes the concentration and mobility of free charged particles in biological tissues.

Dielectric Permittivity

A property characterizing the capacity of biological tissue structures for spatial displacement and the formation of a bulk dipole moment (polarization) under an electric field.

Magnetic Permeability

A parameter indicating the degree of reduction of magnetic field force characteristics in biological tissues relative to a vacuum, equal to $0.99995$ for most cells and body fluids.

Intercellular Fluid Conductivity

The electrical conductivity of the extracellular fluid containing the highest concentration of current carriers (ions), equal to $1\,\text{S/m}$.

Cytosol Conductivity

The electrical conductivity of cytosol containing organelles and large protein macromolecules, which is reduced to $0.003\,\text{S/m}$.

Liquid Media Conductivity

The electrical conductivity range of liquid body media (blood, lymph, bile, cerebrospinal fluid, urine), which has the highest tissue conductivity values between $0.6\,\text{S/m}$ and $2.0\,\text{S/m}$.

Muscle Tissue Conductivity

The electrical conductivity of muscle tissue, which equals $0.2\,\text{S/m}$.

Skin Epidermis Thickness

The thickness of the epidermis over most body areas, measuring $0.07-0.12\,\text{mm}$, and reaching $0.8-1.4\,\text{mm}$ on palmar and plantar surfaces.

Skin Water Content Distribution

The water proportion in skin, comprising $10\%$ of cell mass in the superficial layer and up to $70\%$ in underlying layers.

Dispersion of Electrical Properties

The frequency-dependent alteration of tissue electrical properties resulting from the state and movement of charged particles under electromagnetic fields of varying frequencies.

Low-Frequency Field Behavior

The tissue behavior at low frequencies (up to $10^3\,\text{Hz}$), where cells almost completely shield the electromagnetic field, preventing penetration and ion movement inside.

Mid-Frequency Field Behavior

The tissue behavior at frequencies of $10^4-10^8\,\text{Hz}$, where fields penetrate intracellular structures, involving both interstitial and cytosol ions in total tissue conductivity.

Alpha Dispersion Region

The low-frequency dielectric dispersion region ($\alpha$-dispersion) with a characteristic relaxation frequency of $80\,\text{Hz}$, driven by cell and compartment polarization involving the membrane surface double electrical layer.

Beta Dispersion Region

The mid-frequency dielectric dispersion region ($\beta$-dispersion, $10^4-10^8\,\text{Hz}$) caused by structural polarization of cell membranes, protein macromolecules, phospholipids, and subcellular structures.

Gamma Dispersion Region

The high-frequency dielectric dispersion region ($\gamma$-dispersion) associated with rotational displacement of free water ($10^8-10^9\,\text{Hz}$), bound water ($2 \times 10^{10}\,\text{Hz}$), and low-molecular compounds ($10^9-10^{10}\,\text{Hz}$).

Diamagnetics in Tissues

Biological tissues whose biological molecules have a total net magnetic moment equal to zero, causing minimal attenuation of external magnetic fields.

Paramagnetics in Tissues

Low-molecular compounds with intrinsic magnetic moments independent of external fields (e.g., oxygen, iron salts, hydroperoxides, free radicals), having a magnetic permeability of $1.00005$.

Polarization of Biological Molecules in an Electric Field

The process of biomolecular alignment in an electric field, showing electronic polarization of non-polar molecules (A) and orientational displacement of polar molecules (B).