Intrinsic and Extrinsic Heart Regulation

The rate and force of myocardia contraction (heart rate and force) are dependant on two primary factors: intrinsic factors and extrinsic factors.

Intrinsic factors

* No neural control or hormonal control, such as the intrinsic rate of the Sino-Atrial (SA) Node.

*Normal regulation of the heart

Extrinsic Factors

*Neural and Hormonal control of the heart

* Sympathetic stimulation causes increased rate and strength of contractions

*Parasympathetic stimulation causes decreased rate and strength of contractions