Final answer:
In deep sleep, the body shuts down voluntary components of the sensory-somatic nervous system, which is part of the peripheral nervous system, preventing limb movement.
Step-by-step explanation:
While we are in deep sleep, our bodies shut down our ability to move our limbs. This involves shutting down voluntary components of the peripheral nervous system. The peripheral nervous system (PNS) contains both the autonomic and sensory-somatic nervous systems. The autonomic nervous system controls our involuntary activities, such as the functioning of internal organs and glands, while the sensory-somatic nervous system is responsible for voluntary movements and is associated with conscious perception and voluntary motor responses to the environment.
The autonomic nervous system can be divided into the sympathetic and parasympathetic divisions, which control the "fight or flight" and "rest and digest" responses, respectively. During deep sleep, it is the sensory-somatic part of the peripheral nervous system that is affected, effectively reducing voluntary muscle activity to prevent us from acting out our dreams. Thus, the components that are shut down are the voluntary ones, and they belong to the peripheral nervous system, not the autonomic nervous system.