Resting Membrane Potential: The Electrical Language Of Cells

Resting Membrane Potential: The Electrical Language Of Cells

Question 1. Membrane potential/resting membrane potential.
Answer:

Membrane potential Definition:

• The electrical potential difference across the cell membrane i.e., inside and outside of the cell under resting condition is called membrane potential or resting membrane potential.
• When two electrodes are placed on the cell surface and connected through a suitable amplifier to a cathode ray oscilloscope, no potential difference is observed.
• But, if one of the electrodes is inserted inside the cell, a constant potential difference is observed across the cell membrane.
• This is called resting membrane potential.

Membrane potential Genesis:

• There is negativity inside and positivity outside the cell membrane.
• It is due to distribution of ions across the cell membrane.
• Some K+ diffuses out of the cell while some anions like proteins stay inside the cell.

Question 2. Action potential.
Answer:

Action potential Definition:

The sequence of changes which occur in the membrane potential following excitation is called action potential.

Action potential Phases:

1. Depolarization:

• When the impulse reaches the muscle, the polarized condition is altered.
• The interior of the muscle becomes positive and outside become negative.

2. Repolarization:

• Within a short time, the potential reverses back to the resting membrane potential.
• Interior of the muscle become negative and outside becomes positive.
• This is called repolarization.

Action potential  Properties:

• It is propagative.
• It obeys all or none law.
• It has refractory period.
• It is biphasic.