The Nervous System Collects and Integrates Sensory Information, Formulates a Response Plan, and Produces a Motor Output

In simplest terms, the nervous system (1) collects sensory information from its external or internal environment, (2) con­sciously or unconsciously integrates these various inputs to formulate a response plan, and (3) produces a final motor output that can either change the environment (external or

FIGURE 3-3 General functional organization of the nervous system.

internal) or keep it constant (Figure 3-3). Collecting sensory information and executing the final motor output are the primary responsibilities of the PNS, whereas integration is primarily performed by the CNS. As discussed in Chapter 4, these same functions occur at the level of the individual neuron, which is the principal building block of the nervous system.