BIOPOTENTIALS. Historical Background In 1786, Luigi Galvani found electricity in the muscle of a frog’s leg. In 19 th century other scientists found same.

Presentación del tema: "BIOPOTENTIALS. Historical Background In 1786, Luigi Galvani found electricity in the muscle of a frog’s leg. In 19 th century other scientists found same."— Transcripción de la presentación:

1 BIOPOTENTIALS

2 Historical Background In 1786, Luigi Galvani found electricity in the muscle of a frog’s leg. In 19 th century other scientists found same effect in animals and man. 1903, William Einthoven introduced the string galvanometer, and measured these potentials. 2007/2008 Dr. Mohamed El-Brawany

3 Biopotential Definition: Ionic voltages produced as a result of the electrochemical activity of excitable cells. Measurement: Using transducers to convert ionic potentials into electrical potentials 2007/2008 Dr. Mohamed El-Brawany

4 Excitable Cells Are components of nervous, muscular or glandular tissue Can produce bioelectric potentials as a result of electrochemical activity. 2007/2008 Dr. Mohamed El-Brawany

5 Biopotential states 2007/2008 Dr. Mohamed El-Brawany Resting potential State Action potential State

6 Origin of Biopotential 2007/2008 Dr. Mohamed El-Brawany Intracellular Fluid (saline) NaCl Extracellular Fluid (Water) Semi permeable Membrane - - - - - - - - - - - - - Diffusion Gradient Electrostatic force of repulsion

7 Intra- and Extracellular fluids : Na+, Cl-, K+ Membrane keeps high K i +, Low Na i + and Low Cl i - Membrane 7- 15 nm thick lipoprotein Membrane impermeable to intracellular protein Membrane is moderately permeable to Na+ and freely permeable to K+ and Cl- Living cell properties 2007/2008 Dr. Mohamed El-Brawany

8 Resting Potential State 2007/2008 Dr. Mohamed El-Brawany

9 Resting Potential State 2007/2008 Dr. Mohamed El-Brawany

10 Resting Potential Equation 2007/2008 Dr. Mohamed El-Brawany = + 60 mv = -85 mv = -66 mv

11 R: Universal Gas Constant F: Faraday Constant T : Absolute Temp in degree Kelvin P : Permeability K o, Na o, Cl o : ion concentration outside cell K i, Na i, Cl i : ion concentration inside cell 2007/2008 Dr. Mohamed El-Brawany

12 Resting Potential Equation 2007/2008 Dr. Mohamed El-Brawany

13 Notes N atoms = total charge / electron charge (electrolysis) N moles = N atoms / Avogadros Number Weight (in gram) = Molecular Weight * N moles Avogadro’s Number = 6.03 * 10 23 atoms/mole 2007/2008 Dr. Mohamed El-Brawany