What part of the nervous system is responsible for responding to stimuli from the external environment?

The peripheral nervous system (PNS) plays a crucial role in responding to stimuli from the external environment. It consists of all the nerves outside the central nervous system and includes sensory and motor neurons. The sensory neurons are responsible for transmitting sensory information from the external environment, such as touch, sound, and sight, to the central nervous system for processing.

Moreover, the PNS is divided into two main parts: the somatic nervous system and the autonomic nervous system. While the somatic nervous system specifically controls voluntary movements and transmits sensory information to the CNS, it is the broader peripheral nervous system that encompasses the full scope of sensory input and motor output to the external environment.

In contrast, the central nervous system, which includes the brain and spinal cord, primarily processes and interprets information rather than directly responding to the environment. The autonomic nervous system, a subdivision of the PNS, governs involuntary functions such as heart rate and digestion, and does not directly manage voluntary responses to external stimuli.