HEART RATE IS CONTROLLED BY THE TWO BRANCHES OF THE AUTONOMIC (INVOLUNTARY) NERVOUS SYSTEM.THE SYMPATHETIC NERVOUS SYSTEM (SNS) AND THE PARASYMPATHETIC NERVOUS SYSTEM (PNS).THE SYMPATHETIC NERVOUS SYSTEM RELEASES THE HORMONES (CATECHOLAMINES-EPINEPHRINE AND NOREPINEPHRINE) TO ACCELERATE THE HEART RATE