What system of the body is responsible for the regulation of involuntary functions?

The autonomic nervous system is specifically responsible for the regulation of involuntary functions within the body. This includes essential processes such as heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal, which operate without conscious control.

The autonomic nervous system is divided into two main branches: the sympathetic and parasympathetic nervous systems, which work together to maintain homeostasis by regulating these involuntary actions according to the body’s needs. For instance, during a stressful situation, the sympathetic division prepares the body for "fight or flight" responses, while the parasympathetic division promotes "rest and digest" activities.

In contrast, the central nervous system primarily consists of the brain and spinal cord and is mainly involved in processing information and coordinating voluntary movement, rather than regulating involuntary functions. While the circulatory and respiratory systems play critical roles in maintaining homeostasis, they are not responsible for the regulation of involuntary functions in the way the autonomic nervous system is.