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47. a student is frightened by a loud noise, which results in a hormone being released into the blood. the hormone causes the student's heart to beat rapidly. the two systems that work together to cause this reaction are the endo- crine system that secretes the hormone and the (1) nervous system (3) excretory system (2) reproductive system (4) digestive system

Which factors threaten the forests of north america?

Im home schooled why does my mom make me do such hard work dx