What is the firing rate of a normally functioning SA Node?

The firing rate of a normally functioning SA Node, which is the natural pacemaker of the heart, is typically between 60 and 100 beats per minute (bpm). This range is critical because it represents the intrinsic rate at which the SA Node generates electrical impulses that stimulate the heart to contract. When the SA Node fires at this rate, it ensures that the heart maintains a regular rhythm and adequate cardiac output under normal physiological conditions.

The SA Node's ability to achieve this firing rate is influenced by various factors, including autonomic nervous system input, such as sympathetic and parasympathetic stimulation. Under normal circumstances, the sympathetic nervous system increases heart rate, while the parasympathetic system decreases it, but the basic intrinsic rate remains within the 60-100 bpm range.

Understanding this normal firing rate is fundamental for recognizing dysrhythmias or arrhythmias and for managing cardiac conditions effectively.