Brian banged his shin against a desk and grimaced with pain. he quickly bent over and began rubbing his leg where he'd banged it and the pain he was experiencing started to subside a bit. this phenomenon can best be explained by the

This phenomenon can best be explained by "the gate-control theory".

According to the gate control theory, pain signals are not allowed to achieve the brain when they are produced at the harmed tissues or destinations. They have to experience certain 'neurological gates' at the spinal cord level and these doors decide if the torment signs should achieve the brain or not. As such, pain is seen when the entryway offers path to the torment signs and it is less exceptional or not in the least saw when the door closes for the signs to go through. This theory gives the clarification for why somebody discovers help by rubbing or kneading a harmed or a difficult region.

industry had made the u.s. the richest nation in the world at this time. the second industrial revolution caused growth in industry and transportation, which allowed increased trade between nations.