PHYSICAL CAUSES

Table of contents :


  • radiations
  • pressure 
  • thermic energy 
  • humidity
  • electric energy


  • radiation : energy transport sustained by electromagnetic wave or microscopic particle flow with no need for a supporting medium
  • pressure : force per unit area; symbol P. The SI unit for pressure is the Pascal (Pa), which is one newton per square meter of area
  • thermic energy
  • Laboratory examinations : thermometer, anemometer / velocimeter (measurement of speed, such as speed of flow)
     
  • humidity : the degree of moisture, especially of that in the air.
  • Laboratory examinations : hygrometer, psychrometer
     
  • electric energy

  • Sources : Ohm's law : I = DV/R [A]. R varies from 16,000-80,000 W in stratus corneus of skin to very low values in ionic conductors (e.g. blood, interstitial fluids, very vascularized organs) and wet or sweat skin (2,000 W), higher for direct current (DC) rather than alternate currents (AC), so that ACs are more dangerous, expecially when of low-frequency (domestic currents are typically 50 Hz), while above 10,000 Hz no danger exists. Bipolar contact with potential source is more dangerous than unipolar contact (in which electricity discharges into field); small-surface area contact is more dangerous than wide-surface contact; duration of contact. Insulators prevent discharge of electricity into field : rubber, porcelain and wood are good insulators, while land, wet fields or leather soles are por insulators. Dipoles between hands meets the heart, dipoles between hands and contralateral foot meet heart, while dipoles passing for head meet cerebral centers : dipoles beassing through feet are not dangerous. Tolerance develops in electricists and experimental animal models. Predisposing factors are fatigue, profuse sweating, fever, emotional tension, cardiopathies, alcoholits, thymo-lymphatics, diabetics and hysterics.
    Biological effects of electric current : Symptoms & signs :
    Copyright © 2001-2014 Daniele Focosi. All rights reserved Terms of use  | Legal notices
    About this site  |  Site map  |  Acknowledgements | Open forum  |    |  Current link partners
     Abbreviations and acronyms  |  Medical terminology  |  Add a link  |  Translate this site into your favourite language  |  Softwares


    This website subscribes to the
          HONcode principles of the HON Foundation. Click to verify.
    PicoSearch
     

    Search 



    Search 
    for 



    Search Medical Dictionary 
    for