What does the autonomic nervous system regulate?

The autonomic nervous system (ANS) primarily regulates the functions of glands and the muscles of internal organs. This system operates involuntarily, meaning it controls bodily functions that do not require conscious thought, such as heart rate, blood pressure, digestion, and respiratory rate.

The effectiveness of the autonomic nervous system lies in its two subdivisions: the sympathetic and parasympathetic nervous systems, which work together to maintain homeostasis in the body. The sympathetic system is often associated with the 'fight or flight' response, preparing the body for stressful situations, while the parasympathetic system is linked to 'rest and digest' functions, promoting relaxation and recovery.

While the other options mention important aspects of the nervous system, they are outside the scope of what the autonomic nervous system specifically regulates. Skeletal muscle movement refers to the somatic nervous system, reflexes and spinal cord functions pertain to reflex arcs and are under somatic control as well, and voluntary actions relate to actions that we consciously decide to perform, also governed by the somatic nervous system. Thus, the primary role of the autonomic nervous system is best described in relation to the regulation of glands and internal organ muscles.