Final answer:
The peripheral nervous system (PNS) includes all nerves and ganglia outside the brain and spinal cord, connecting the central nervous system (CNS) to the rest of the body. It consists of sensory and motor divisions, as well as the autonomic and sensory-somatic nervous systems, playing a vital role in information relay and response to the external environment.
Step-by-step explanation:
The Peripheral Nervous System
The peripheral nervous system (PNS) is the part of the nervous system that consists of the nerves and ganglia on the outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system (CNS), which includes the brain and spinal cord, to limbs and organs, essentially serving as communication lines linking all parts of the body. While the CNS is responsible for the brain and spinal cord, the PNS encompasses all other nervous tissue. The peripheral nervous system is divided into the sensory division that transmits information from the body to the CNS, and the motor division that conveys commands from the CNS to the muscles. Additionally, the PNS includes the autonomic nervous system, which operates without conscious control, and the sensory-somatic nervous system, which oversees voluntary actions and the conveyance of sensory information.
The longest nerve in the human body, the sciatic nerve, which runs from the lower back down to the foot, is an example of a peripheral nerve. Some nerves in the peripheral nervous system are actually found within the cranial or vertebral cavities, but their primary function is to relay information to and from the CNS, making them a component of the PNS. Overall, the PNS is essential for the relay of information between the brain and spinal cord and the rest of the body, ensuring proper functioning and response to the external environment.