AP Psychology Practice Test 2026 - Free AP Psychology Practice Questions and Study Guide

The nervous system is defined as the body's electrochemical communication system because it comprises the network of neurons and glial cells that transmit signals throughout the body. This system is responsible for processing sensory information, coordinating responses, and controlling various functions, from movement to cognition. It includes the central nervous system (the brain and spinal cord) and the peripheral nervous system, which includes all other neural elements.

The other options do not accurately encompass the full scope of the nervous system. While muscles are essential for movement, they are part of the muscular system rather than the nervous system itself. The brain is a critical component of the central nervous system, but referencing the heart suggests a blend with the circulatory system, which operates independently from the nervous system. Lastly, the skeletal structure connects muscles but is part of the musculoskeletal system, not the nervous system. Hence, identifying the nervous system as the electrochemical communication framework highlights its unique and integrative role in maintaining bodily functions and responding to the environment.