Given a scientific question, generate a correct answer to it.

Input: Consider Input: The nervous system is characterized by electrical signals that are sent from one area to another. whether those areas are close or very far apart, the signal must travel along this?

Output: axon

Input: Consider Input: Renal plasma flow equals the blood flow per minute times the what?

Output: hematocrit

Input: Consider Input: What do heterotrophic animals usually consume?
Output: other organisms