Lecture 3-Electricity Applied to the Human Body (4).ppt PDF

PX2144 Biophysics Biophysics Application of Electricity to the Human Body PX2144 Biophysics Electricity in the Human Body Flow of charged atoms called ions An ion is an atom or group of atoms carrying an electric charge by virtue of havi...

PX2144 Biophysics Biophysics Application of Electricity to the Human Body PX2144 Biophysics Electricity in the Human Body Flow of charged atoms called ions An ion is an atom or group of atoms carrying an electric charge by virtue of having gained or lost one or more valence electrons Ions may exist in solid, liquid, or gaseous environments Ions existing in a liquid state are electrolytes PX2144 Biophysics Electricity in the Human Body An electrolyte is any compound that, in solution, conducts electricity Cells create electrical energy as ions move from the solutions inside the cells of our body to the solutions outside the cells This is very similar to a battery where one end has a larger concentration of positively charged particles and the other end a greater concentration of negatively charged particles PX2144 Biophysics Determinants of Electrical Injury Direct injury affect caused by the current and by conversion of electrical to thermal energy Indirect affect caused by severe muscle contractions Depends on the intensity of the electrical current Ohm’s law: I = V / R Because resistance varies around the body the same voltage will produce different currents PX2144 Biophysics Determinants of Electrical Injury Least resistance found in nerves, blood mucous membranes and muscles Highest resistance found in bones, fat and tendons Skins resistance is intermediate PX2144 Biophysics Determinants of Electrical Injury. The Skin The skin is the primary resistance against electrical current Resistance ranges from between 40,000 to 100,000Ω depending on thickness. Moisture content can reduce resistance to 10ms expect fibrillation – If contact is