AP PSYCHOLOGY

Detailed explanation-1: -Müller had used the nerve impulse as an example of a vital function that would never be submitted to experimental measurement. Helmholtz found that this impulse was perfectly measurable and had the remarkably slow speed of some 90 feet (27 metres) per second.

Detailed explanation-2: -With his investigations, Helmholtz entered the history of the experimental life sciences as the first scientist to make precise measurements of nervous action. In nerve-muscle preparations from the frog, Helmholtz measured a propagation velocity of stimuli between 25 and 43 meters per second2.

Detailed explanation-3: -Normal impulses in peripheral nerves of the legs travel at 40–45 m/s, and those in peripheral nerves of the arms at 50–65 m/s. Largely generalized, normal conduction velocities for any given nerve will be in the range of 50–60 m/s.

Detailed explanation-4: -He compared the curves that were produced when the nerve was stimulated either close to, or distant from, the muscle. From the curve’s displacement, he calculated the speed of signal propagation in the nerve-and got the same value he had calculated using his electromagnetic method.

Detailed explanation-5: -Conduction velocity was calculated by dividing the distance between two stimulus sites by the interstimulus interval (corrected by the refractory period).