Which part of the nervous system regulates involuntary bodily functions?

The correct answer is the autonomic nervous system, which is responsible for regulating involuntary bodily functions. This includes processes that occur automatically without conscious control, such as heart rate, digestion, respiratory rate, and reflexes.

The autonomic nervous system operates through two main divisions: the sympathetic and parasympathetic systems. The sympathetic system prepares the body for stressful or emergency situations, often referred to as the "fight or flight" response, while the parasympathetic system promotes relaxation and conservation of energy, known as the "rest and digest" state.

In contrast, the central nervous system primarily comprises the brain and spinal cord and is responsible for processing sensory information and coordinating responses. The peripheral nervous system connects the central nervous system to the limbs and organs but includes both voluntary and involuntary functions. Lastly, the somatic nervous system controls voluntary movements by relaying messages from the central nervous system to the skeletal muscles, which is contrary to the involuntary functions of the autonomic nervous system.