If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content


Course: MCAT > Unit 3

Lesson 1: Chemical and physical sciences practice passage questions

The speed of a neural impulse


The sciatic nerve is the longest and widest nerve in the human body. The sciatic nerve goes from the lower back through the leg all the way down to the ankle and foot.
A study is done of different peoples sciatic nerves. In the study, the length of the sciatic nerve was measured, as well as the speed at which touch sensations were transmitted along the sciatic nerve. These measurements were taken through the use of a Nerve Conduction Velocity (NCV) test. The NCV process begins with electrically stimulating the designated nerve with a surface patch node. A separate node is placed further along down the vein in the direction of the neural flow. The second node records the new electric stimulus’ time and intensity. The distance between the two nodes and the time taken for the stimulus to reach the second node from the first node are used to calculate the velocity with which the electric pulse travels. This final number is referred to as the Nerve Conduction Velocity.
The results of the study are shown in the table below.
Table 1. Results of the NCV study.
PersonLength of sciatic nerve (lower back to foot)Nerve Conduction Velocity
A0.9 meters30meters/second
B0.80 meters40meters/second
C1.0 meters50meters/second
D0.80 meters20meters/second
How long after being touched on his or her foot would it take for the nerve impulse to travel the entire length of the sciatic nerve of person C?
Choose 1 answer: