Step 1: Rheobase Definition.
Rheobase is the minimum current intensity needed to elicit a response from excitable tissue when applied for an indefinite duration. This parameter is essential for assessing nerve and muscle tissue excitability.
Step 2: Chronaxie Explained.
Chronaxie, while related to rheobase, is distinct. It signifies the minimum duration a stimulus must be applied at double the rheobase strength to evoke a response.
Step 3: Examination of Alternatives.
- (3) Van Hoff Point: Unrelated to electrical stimulation; pertains to the effect of temperature on chemical reaction rates.
- (4) Lewis Stimulation Point: This term does not denote an electrical stimulation threshold but refers to a different phenomenon.
Step 4: Final Determination.
Consequently, (2) Rheobase is the correct selection, representing the minimal stimulus current required for a response at infinite stimulus duration.