Dual innervation refers to the concept in physiology where an organ or tissue receives nerve supply from both the sympathetic and parasympathetic divisions of the autonomic nervous system. This means that the function of the organ is regulated by these two opposing systems, allowing for a delicate balance in physiological response.
The sympathetic nervous system typically prepares the body for ‘fight or flight’ responses, increasing heart rate, dilating pupils, and redirecting blood flow to muscles. In contrast, the parasympathetic nervous system promotes ‘rest and digest’ activities, slowing the heart rate, enhancing digestion, and conserving energy.
For example, the heart is innervated by both systems: the sympathetic nerves increase heart rate and force of contraction, while the parasympathetic nerves (primarily via the vagus nerve) serve to decrease the heart rate. This interplay ensures that the heart responds appropriately to varying conditions and demands placed upon it.
In summary, dual innervation is crucial for maintaining homeostasis and enables the body to react effectively to changing internal and external environments.