You are studying alone in your room late at night when you hear a loud noise downstairs. Your heart beat has increased significantly and your breathing is deeper. You wonder if a burglar has entered the house so you decide to investigate. When you cautiously walk downstairs you discover your cat has knocked over a plant stand. Your body begins to relax and return to normal. Which part of your nervous system is responsible for returning you to a normal state

The parasympathetic nervous system (PNS) is one of the three divisions of the autonomic nervous system. The PNS rests and relaxes the body after it is at a heightened state of arousal (usually due to the fight and flight system being activated). The PNS is responsible for returning heart beat back to a normal rate, slowing down rapid breathing, relaxing muscles, constricting pupils and relaxing the digestive and excretory system so that they return to normal functioning. 

explanation:

on disadvantage of hydroelectric power is the cost. another disadvantage of using hydroelectric power is finding a water source powerful enough to harvest hydroelectric power.