As soon as PTH does its job, PTH needs to be taken out of commission to prevent overdoing it. The only way our body can know if PTH has done its job is by evaluating calcium levels in the blood. When the calcium levels increase, no more PTH should be made. This is an example of negative feedback. In all cases of negative feedback, the end result affects the pathway that got it there.
Julia Cook. "It doesn’t matter how old you are, accepting criticism is difficult. Sometimes it’s even hard to know exactly what to say when someone gives you a compliment. That’s certainly the case for R.J. Read along with “Thanks for the Feedback…I Think” and you’ll see how R.J. learns how to accept criticism and compliments the right way!"