NEETZoologyNeural Control and Coordination
What happens to the membrane at site A when a stimulus is applied?
Options
- AThe membrane becomes freely permeable to potassium ions (K⁺).
- BThe membrane becomes freely permeable to sodium ions (Na⁺).
- CThe membrane becomes impermeable to both sodium ions (Na⁺) and potassium ions (K⁺).
- DThe membrane becomes permeable to both sodium ions (Na⁺) and potassium ions (K⁺).
Correct answer
B. The membrane becomes freely permeable to sodium ions (Na⁺).
Step-by-step solution
is depolarised. The outer surface of the axonal membrane possesses a positive charge while its inner surface becomes negatively charged and therefore is polarised The sodium-potassium pump transports 3 Na⁺ ions outwards for 2 K⁺ ions into the cell. The action potential of the plasma membrane of a neuron is the electrical potential difference across the plasma membrane. The rise in permeability to Na⁺ is short-lived and is followed by a rise in permeability to K⁺. K⁺ diffuses outside the membrane, restoring the rest