Origin of bio-potential, Resting potential, Action Potential

1. BIOPOTENTIALSBIOPOTENTIALSBIOPOTENTIALSBIOPOTENTIALS
Dr T M INBAMALAR M.E. Ph DDr T M INBAMALAR M.E. Ph DDr T M INBAMALAR M.E. Ph DDr T M INBAMALAR M.E. Ph D
PROFESSOR/ECEPROFESSOR/ECEPROFESSOR/ECEPROFESSOR/ECE
RMK COLLEGE OF ENGINEERING AND TECHNOLOGYRMK COLLEGE OF ENGINEERING AND TECHNOLOGYRMK COLLEGE OF ENGINEERING AND TECHNOLOGYRMK COLLEGE OF ENGINEERING AND TECHNOLOGY

2. Origin of Bioelectric potentialsOrigin of Bioelectric potentialsOrigin of Bioelectric potentialsOrigin of Bioelectric potentials
The systemssystemssystemssystems inininin thethethethe humanhumanhumanhuman bodybodybodybody generate their on
monitoringmonitoringmonitoringmonitoring signalssignalssignalssignals when they carry out their
functions.
These signals provide usefulusefulusefuluseful informationinformationinformationinformation aboutaboutaboutabout
theirtheirtheirtheir functionfunctionfunctionfunction.theirtheirtheirtheir functionfunctionfunctionfunction.
BioelectricBioelectricBioelectricBioelectric potentialspotentialspotentialspotentials areareareare actuallyactuallyactuallyactually ionicionicionicionic voltagesvoltagesvoltagesvoltages
produced as a resultresultresultresult ofofofof electroelectroelectroelectro chemicalchemicalchemicalchemical activityactivityactivityactivity
of certain cell.
TransducersTransducersTransducersTransducers are used to convert these ionicionicionicionic
potentialspotentialspotentialspotentials inininin totototo electricalelectricalelectricalelectrical signalssignalssignalssignals

3. Resting and Action potentialsResting and Action potentialsResting and Action potentialsResting and Action potentials
Certain types of cells within the body, such as
nervenervenervenerve andandandand musclemusclemusclemuscle cellscellscellscells areareareare encasedencasedencasedencased inininin aaaa semisemisemisemi
permeablepermeablepermeablepermeable membranemembranemembranemembrane....
This membrane permitspermitspermitspermits somesomesomesome substancessubstancessubstancessubstances totototo passpasspasspass
throughthroughthroughthrough whilewhilewhilewhile othersothersothersothers areareareare keptkeptkeptkept outoutoutout....
SurroundingSurroundingSurroundingSurrounding thethethethe cellscellscellscells of the body are the bodybodybodybody
fluidsfluidsfluidsfluids
These fluidsfluidsfluidsfluids areareareare conductiveconductiveconductiveconductive solutionssolutionssolutionssolutions containingcontainingcontainingcontaining
chargedchargedchargedcharged atomsatomsatomsatoms known as ions

4. Resting potentialsResting potentialsResting potentialsResting potentials
The principle ionsionsionsions areareareare sodium(Na+)sodium(Na+)sodium(Na+)sodium(Na+) Potassium(K+)Potassium(K+)Potassium(K+)Potassium(K+) andandandand
chloride(Cchloride(Cchloride(Cchloride(C----))))
The membrane of excitable cells permitpermitpermitpermit entryentryentryentry ofofofof
Potassium(K+)Potassium(K+)Potassium(K+)Potassium(K+) andandandand chloride(Cchloride(Cchloride(Cchloride(C----)))) ionsionsionsions but blocksblocksblocksblocks thethethethe entryentryentryentry ofofofof
sodium(Na+)sodium(Na+)sodium(Na+)sodium(Na+) ionsionsionsions....
So insideinsideinsideinside thethethethe cellcellcellcell isisisis moremoremoremore negativenegativenegativenegative than outside cellSo insideinsideinsideinside thethethethe cellcellcellcell isisisis moremoremoremore negativenegativenegativenegative than outside cell
This membrane potentials is called RestingRestingRestingResting potentialspotentialspotentialspotentials
This potential is measuredmeasuredmeasuredmeasured fromfromfromfrom insideinsideinsideinside thethethethe cellcellcellcell withwithwithwith
respectrespectrespectrespect totototo bodybodybodybody fluidsfluidsfluidsfluids....
So restingrestingrestingresting potentialpotentialpotentialpotential ofofofof aaaa cellcellcellcell isisisis negativenegativenegativenegative.

5. Resting potentials/PolarizationResting potentials/PolarizationResting potentials/PolarizationResting potentials/Polarization
This resting potential ranging fromThis resting potential ranging fromThis resting potential ranging fromThis resting potential ranging from ----60mv to60mv to60mv to60mv to ----100100100100 mvmvmvmv....
Cell in the resting state is called polarizedCell in the resting state is called polarizedCell in the resting state is called polarizedCell in the resting state is called polarized cell.cell.cell.cell.

6. Depolarization of cellDepolarization of cellDepolarization of cellDepolarization of cell
When a cell is exited, the membrane change its characteristiccell is exited, the membrane change its characteristiccell is exited, the membrane change its characteristiccell is exited, the membrane change its characteristic.
The sodium ions are rushed in to the cellsodium ions are rushed in to the cellsodium ions are rushed in to the cellsodium ions are rushed in to the cell.
At the same time potassium ions try move from insidepotassium ions try move from insidepotassium ions try move from insidepotassium ions try move from inside.
After a equilibrium state is reachedequilibrium state is reachedequilibrium state is reachedequilibrium state is reached, the sodium is moved back tosodium is moved back tosodium is moved back tosodium is moved back to
outsideoutsideoutsideoutside

7. Action PotentialsAction PotentialsAction PotentialsAction Potentials

8. Re PolarizationRe PolarizationRe PolarizationRe Polarization
Cell comes from dededede polarizedpolarizedpolarizedpolarized statestatestatestate inininin totototo polarizedpolarizedpolarizedpolarized statestatestatestate isisisis calledcalledcalledcalled ReReReRe
polarizationpolarizationpolarizationpolarization....

9. Resting and Action potentialsResting and Action potentialsResting and Action potentialsResting and Action potentials

10. Nernst equation:Nernst equation:Nernst equation:Nernst equation:

12. Half Cell Potential or Electrode PotentialHalf Cell Potential or Electrode PotentialHalf Cell Potential or Electrode PotentialHalf Cell Potential or Electrode Potential
• Voltage developed at an ElectrodeVoltage developed at an ElectrodeVoltage developed at an ElectrodeVoltage developed at an Electrode---- Electrolyte interfaceElectrolyte interfaceElectrolyte interfaceElectrolyte interface
• When a metal comes in contact with an electrolyte (body fluid), thenWhen a metal comes in contact with an electrolyte (body fluid), thenWhen a metal comes in contact with an electrolyte (body fluid), thenWhen a metal comes in contact with an electrolyte (body fluid), then
there is a tendency for the electrode to discharge ions into solutionthere is a tendency for the electrode to discharge ions into solutionthere is a tendency for the electrode to discharge ions into solutionthere is a tendency for the electrode to discharge ions into solution
as a result of which charge gradient is createdas a result of which charge gradient is createdas a result of which charge gradient is createdas a result of which charge gradient is created

13. QUESTIONSQUESTIONSQUESTIONSQUESTIONS