Which system is responsible for controlling the heart and internal organs?

The automatic nervous system, more commonly referred to as the autonomic nervous system, is responsible for regulating involuntary body functions, including the activity of the heart and other internal organs. This system operates without conscious control and is critical for maintaining homeostasis in the body. It consists of two main divisions: the sympathetic and parasympathetic nervous systems. The sympathetic division prepares the body for stress-related activities (often termed the "fight or flight" response), while the parasympathetic division promotes rest-and-digest functions, aiding in recovery and energy conservation.

In contrast, the somatic nervous system is involved in voluntary muscle movements and the relay of sensory information to the central nervous system. The central nervous system, which includes the brain and spinal cord, processes information and coordinates actions but does not directly manage the autonomous functions of organs. The peripheral nervous system encompasses all nerves outside the central nervous system, including both sensory and motor pathways, but it does not specifically denote the involuntary control of heart and organ function as the autonomic nervous system does. Thus, the autonomic nervous system is the most accurate choice for controlling the heart and internal organs.