Question

a. What is the resting potential? What characterizes it? Why is it important?

b. What is the action potential? What characterizes it? Why is it important?

Answer 1

1. Resting Potential, Action Potential, Absolute Refractory period, Relative refractory period and Synaptic transmission are the stages of signal transmission inside the neuron.

Resting potential: - It is the potential maintained by the neuron while the neuron is inactive. The positive charges will be stronger outside the neuron’s membrane. All together the neuron will have a slight negative charge (-60millivolt to -95millivolt).

Characteristics:

• The outside part of the membrane will be more positively charged due to the higher concentration of Na+, Cl-, and Ca2+ ions outside.
• Inside the cell, there will be K+ ions and negatively charged anions.
• The ligand-gated channels will be closed.
• Inside the cell, there will be a slight negative charge of -60mV to +95mV.
• The neuron will be inactive at this period of time.
• It will be ready to activate.

Importance of the resting potential: It is important to have an equilibrium stage with less action and a comparatively inactive stage for the passing of the impulse. This will help in the formation of the action potential which is the process by which the signal is transmitted. A stage like absolute refractory period resists the formation of the action potential.

2. Action potential: - An action potential is a rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane with a characteristic pattern. Due to the rise in the potential depolarization occurs.

Depolarization: Gaining more positive charge by receiving Na+ Ions. The cell will become less polar and this state is called Excitatory Post-Synaptic Potential (EPSP)

As the Ligand gate opens Na+ ions enter inside the cell by giving a more positive charge to the cell.

Characteristics:

• Rise and subsequent fall in the voltage across the cell.
• Depolarization occurs and leads to EPSP.
• Ligand gate opens.
• Na+ and Ca2+ entry into the cell.
• Ligand gate maintains the flow of Na+ ions in an optimum level.
• Neuron will be active at this moment of time.
• The Depolarization is continued thought the cell.

Importance of the Action potential: This stage creates a charge difference in the cell and helps the signal pass through the neuron. This stage is the most important stage of the neuron transmission.