which part of the heart normally controls the heart rate
Heart rate While heart rhythm is regulated entirely by the sinoatrial node under normal conditions, heart rate is regulated by sympathetic and parasympathetic input to the sinoatrial node. The accelerans nerve provides sympathetic input to the heart by releasing norepinephrine onto the cells of the sinoatrial node (SA node), and the vagus nerve provides parasympathetic input to the heart by releasing acetylcholine onto sinoatrial node cells. Therefore, stimulation of the accelerans nerve increases heart rate, while stimulation of the vagus nerve decreases it.[8]
Heart The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system.[1] Blood provides the body with oxygen and nutrients, as well as assists in the removal of metabolic wastes.[2] In humans, the heart is located between the lungs, in the middle compartment of the chest.[3]