Question

Which of the following statement(s) is/are CORRECT about neuronal membrane and neuronal action potential?

• A. Application of an outward current depolarizes the neuronal membrane
• B. Application of an inward current depolarizes the neuronal membrane
• C. Increasing the stimulus strength increases the amplitude of neuronal action potential
• D. Increasing the stimulus strength decreases the latency of neuronal action potential

Hint:

An inward current depolarizes the membrane, while an outward current hyperpolarizes it. The latency of the action potential can be decreased with a stronger stimulus.

Answer 1

The Correct Option is B, D

Let's analyze each statement: 
Step 1: Understanding depolarization. 
Depolarization of the neuronal membrane occurs when the inside of the cell becomes less negative compared to the outside. 
Application of an outward current will move positive charge out of the cell or negative charge into the cell, making the inside more negative, which hyperpolarizes the membrane (option A is incorrect).
Application of an inward current brings positive charge into the cell or removes negative charge, making the inside more positive, which depolarizes the membrane (option B is correct).
Step 2: Stimulus strength and action potential amplitude. 
The amplitude of a neuronal action potential is generally fixed and does not change with stimulus strength. This is known as the "all-or-nothing" principle (option C is incorrect). 
Step 3: Stimulus strength and latency.
Increasing the stimulus strength typically leads to a faster rise in the membrane potential, and can decrease the latency (time taken for the action potential to initiate). This is because the higher the stimulus, the quicker the threshold is crossed, reducing the latency of the action potential (option D is correct). Thus, the correct answers are (B) and (D).