When a stimulus is produced it signifies the production of sensation in the sensory organs. This sensation through the sensory organs (eyes, ears, nose, skin and tongue) is sent to the sensory nerve connected to these sense organs. These sensory nerves send nerve impulses through the nerve fiber to the spinal cord. From the spinal cord the nerve impulse is transferred to motor nerves.
The motor nerve then sends response to the stimulus though the same path to the region from which stimulus was received and thus the body responds through muscular activity. Such as removal of heat from the heated object if heated sensations were received.
It is hard to name on that is responsible for all but polution has a large impact on our daily life,hope this helped
~The images below will hopefully help. :)
*The pulley is a lever, and it helps lifts things higher with less force then trying to normally pick it up.
Explanation:
The active trap in the Venus Flytrap ( dionaea muscipula )
I believe the answer is Genes??If that is the answer. Hope this helps