Question

The charge on the outer side of neuron is

• A. Positive
• B. - ve
• C. Zero
• D. Alternate - ve and + ve

Answer 1

The Correct Option is A

The correct option is (A): Positive

Answer 2

Explanation:

• When a neuron is at rest, it is negatively charged. The inside of the cell is approximately 70 mV more negatively charged as compared with the outside. This voltage is called the resting membrane potential.
• Resting membrane potential is caused by differences in the ion concentrations within the cell and outside the cell.
• The difference in the number of positively charged potassium ions (K⁺) inside and outside the cell dominates the resting membrane potential.
• At rest, K+ ions accumulate inside the cell, establishing a negative resting membrane potential by favoring their movement against the concentration gradient. 
• This potential is maintained by elevating cation concentrations outside the cell relative to the cytoplasm. 
• The cell's negative charge results from greater permeability to potassium ions than sodium ions. 
• Neurons maintain high internal potassium concentrations and high external sodium concentrations through leakage channels allowing cation diffusion.
• Notably, neurons feature more potassium leakage channels than sodium leakage channels, causing potassium to exit the cell faster than sodium enters. 
• The net efflux of cations results in a negative interior relative to the exterior. 
• The sodium-potassium pump, by transporting two K+ ions in and three Na+ ions out per ATP, reinforces the resting potential. 
• As more cations exit than enter, the cell interior remains negatively charged. 
• Additionally, chloride ions (Cl–) accumulate externally due to repulsion by negatively charged cytoplasmic proteins.