Which system is responsible for regulating heart rate and digestion?

The autonomic nervous system is the correct answer because it plays a crucial role in regulating involuntary bodily functions, which include heart rate and digestion. This system operates automatically and is divided into two main branches: the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system is involved in the body's 'fight or flight' response, which increases heart rate and inhibits digestion. In contrast, the parasympathetic nervous system promotes a 'rest and digest' state, slowing the heart rate and enhancing digestive processes. Together, these branches work to maintain homeostasis within the body.

Unlike the central nervous system, which includes the brain and spinal cord and is primarily responsible for processing information and coordinating voluntary movements, the autonomic nervous system specifically targets automatic functions. The peripheral nervous system encompasses both the autonomic and somatic divisions, with the latter controlling voluntary muscle movements. Therefore, the autonomic nervous system is the most precise choice for the regulation of heart rate and digestion.