Magnetotherapy

Effects of magnetic fields – magnetotherapy

. Basic concepts:

- Magnetic fields are produced either around permanent magnets or around a conductor with moving electric charges. It could be classified as:

o Static fields: in which the magnetic field intensity value remains unchanged with time. This type of field is created around permanent magnets or conductors carrying direct current (DC).

o Alternating fields: the intensity value is periodic changes with time. This type of field is found around conductors carrying alternative current (AC).

o An impulse magnetic field: arises around conductors carrying electric impulses. by moving electric charges and the intrinsic magnetic moments of elementary particles associated

- Magnetic flux density (magnetic induction) B: is the magnetic flux ( in a unit area (A) placed rectangular to the direction of the magnetic forces lines. B=/A [T(tesla)]

o A homogeneous magnetic field has in every point of the part of space under consideration equal magnitude ad direction.

o Non-homogeneous magnetic fields, the magnitude ad direction vary within this space.

- the magnetic induction (B) is proportional to the magnetic field strength H[A/m],the factor of proportionality is the magnetic permeability(u ) B= u.H

 Magnetoelectric effects:

- Magnetic flux density B depends on the magnetic permeability of the medium ( u ): u=ur.u0

o Ferromagnetic substances - u r >>1.

o Diamagnetic substances - u r is slightly lower than 1

o Paramagnetic substances - u r is slightly higher than 1. (u 0 is permeability of vacuum – 4.10-7 N.A-2)

-Body tissues are composed almost only from diamagnetic and paramagnetic substances. Magnetic fields can induce electric voltages and currents in biological medium (due to action of Lorentz force on moving electrical charges, or by action of Faraday force in varying magnetic fields). The induced voltages are lower than the membrane potentials. -Voltage induced (low) by magnetic field can influence the biological media, it is supposed that, it influences the membrane receptors and this way changes the biological reactions.

- In a strong magnetic field, the diamagnetic and paramagnetic molecules orient themselves to minimise their free energy. In non-homogeneous fields with big gradients, a translation and rotational movements of ferromagnetic compounds takes place (in living organisms negligible). - A strong magnetic field (over 1 T) would reduce the flow rate of laminar streaming in a tube.

- Indirect action of the magnetic field as it mediated by free radicals arising as a consequence of magnetochemical reactions.

- We can say that a stable magnetic field of high intensity inhibits metabolic processes, but a varying one stimulates them. These changes are transient. - The interactions of magnetic fields with human tissues are utilised in both diagnostics and therapy.

 Main component of therapeutic effect of Magnetic field:

- Almost all magnetotherapeutic sources are with variable magnetic field, f=50Hz, and or pulsed filed 2-50 Hz.

Main mechanism: (main therapeutic effects of magnetic field)

o Magnetic field induces electric current in the living cell, which influence membrane systems of the cell by acting on membrane receptors and ionic changes.

o Membrane permeability and metabolic activity of cells may be increased.

o Free radicals and other chemical active substance formed in biological fluids influence antioxidative enzymatic systems, which may have complexes changes in the tissue:

'''- Vasodilatation

- Anti-oedematous effect;'''