1. Electrical changes
Vd. Mrinal N Rudragoudar
Asst Professor Dept Of Kriya Sharir
SMVVS RKM AMCH PG & RESEARCH
CENTER
Email-drmnr1991@gmail.com
Mobile -9036632670
2. INTRODUCTION
• Usually muscles contract when it is
stimulated.
• Contraction refers to shortening of muscle
fibers.
• It is a physical / mechanical event.
3. CHANGES DURING CONTRACTION
• Electrical changes
• Physical changes
• Histological changes
• Chemical changes
• Thermal changes
4. ELECTRICAL CHANGES
• It occurs both during resting and active
condition.
• It has two potentials like RMP & AMP.
• It is measured by using cathode ray
oscilloscope or computerized polygraph.
5. RESTING MEMBRANE POTENTIAL
• It is defined as the electrical potential
difference across the cell membrane( between
inside & out side the cell ) under resting
condition.
• It is also called membrane potential ,
transmembrane potential, transmembrane
potential gradient.
6. RMP IN DIFFERENT TISSUES
• Neuron : - 70 mV
• Skelton muscle fiber : -90mV
• Cardiac muscle fibers: -85 to -95 mV
• Smooth muscle cell : -50 to - 95 mV
• Erythrocytes : -12mV
7. IONIC BASIS
• RMP is maintained by movement of ions,
which produces ionic imbalance across the cell
membrane.
• Sodium-potassium pump
• Selective permeability of cell membrane
8. Sodium-potassium PUMP
• Actively transported across the cell.
• 3 Na ions travels out of the cell
• 2 K ions travels inside the cell
• By using ATP
• Hence more positivity is pumped outer than
inside.
• It leads to more positivity outside the cell &
negativity inside the cell.
9. SELECTIVE PERMEABILITY OF CELL
MEMBRANE
• It is mainly depend upon transport channels.
• Most of the channels are gated
• Channels for major ions (protein, phosphate,
sulfate compound)-
• Leak channels( passive channels which allow
movement of positive ions across the cell)
10. ACTION MEMBRANE POTENTIAL
• It is series of electrical changes that occurs in
the membrane potential when muscle or
nerve is stimulated.
• It occurs in two phases like
• Depolarization
• Repolarization
11. DEPOLARIZATION
• It is the initial stage of action potential
• Inside becomes positive and outside becomes
negative
• This is polarized state.
12. REPOLARIZATION
• In this phase the muscle reverse back to
resting membrane.
• It takes place within a short period of time
