Golgi Tendon Organ, its the means by which your body tells your muscles in most cases to either contract with all their might or relax completely in the event of crisis. It has other functions that I don't fully understand but that should be the jist of it. I'm SURE Robb, Greg or someone else more educated than I can correct me if I'm wrong or at least elaborate on the subject further if they so choose.
I'm not so schooled myself to be honest..... I am fixin' on doin' some book lernen event-uly!
I know two things real well though, workin out real hard, and shooten things eh...