Question

functions involuntarily in times of stress
spinal nerve extending from the base of
the spine down the thigh, lower leg, and
foot
agent of change (light, sound, touch)
that evokes a response
space through which a nervous impulse
travels between nerve cells or between
nerve and muscle or glandular cells
canals in the brain that contain
cerebrospinal fluid

Explanation:

• "Spinal nerve extending from the base of the spine down the thigh, lower leg, and foot": The sciatic nerve is the longest nerve in the body and fits this description.
• "Agent of change (light, sound, touch) that evokes a response": A stimulus is something that causes a response, so this matches "stimulus".
• "Space through which a nervous impulse travels between nerve cells or between nerve and muscle or glandular cells": A synapse is the gap where nerve impulses are transmitted, so this is "synapse".
• "Canals in the brain that contain cerebrospinal fluid": The ventricles of the brain are the cavities that hold cerebrospinal fluid, so this is "ventricles of the brain".

Answer:

• Spinal nerve extending from the base of the spine down the thigh, lower leg, and foot: sciatic nerve
• Agent of change (light, sound, touch) that evokes a response: stimulus
• Space through which a nervous impulse travels between nerve cells or between nerve and muscle or glandular cells: synapse
• Canals in the brain that contain cerebrospinal fluid: ventricles of the brain