Which part of the nervous system is responsible for controlling involuntary actions such as heart rate?

The autonomic nervous system is indeed the part of the nervous system responsible for controlling involuntary actions, such as heart rate, digestion, and respiratory rate. This system operates automatically and unconsciously, regulating bodily functions without the need for conscious thought. It is further divided into two branches: the sympathetic nervous system, which prepares the body for 'fight or flight' responses, and the parasympathetic nervous system, which promotes 'rest and digest' activities.

While the somatic nervous system controls voluntary movements through skeletal muscles, the central nervous system processes information and coordinates activity between different parts of the body but does not directly control involuntary functions. The peripheral nervous system encompasses all nerves outside the central nervous system, including both the somatic and autonomic systems, but it is the autonomic nervous system that specifically manages involuntary actions such as heart rate. Thus, the correct choice highlights the specialization of the autonomic system in regulating essential bodily functions autonomously.