Thursday, March 27, 2014

Heart Rate Regulation

Although the heart has its own electrical conducting system, the SA node and AV node, the regulation of the heart rate is conducted by two types of autonomic nervous system fibers, sympathetic and parasympathetic, making up what is called the cardiac plexus. This fiber network is situated at the base of the heart. Sympathetic fibers coming from the left sympathetic trunk are responsible for the heart rate acceleration when they are affected by noradrenaline hormone under stress, for example, while parasympathetic fibers, that branch off from the vagus nerve (X), are responsible for the deceleration (decrease) of the heart rate when at rest.