What is the central nervous system primarily made up of?

The central nervous system (CNS) is fundamentally comprised of the brain and spinal cord. These two components work together to process information and coordinate responses throughout the body. The brain serves as the control center, responsible for higher cognitive functions, sensory processing, and decision-making, while the spinal cord acts as the main conduit for transmitting signals between the brain and the rest of the body.

Other options, while related to the nervous system or bodily functions, do not constitute the central nervous system. Nerves and ganglia, for example, are part of the peripheral nervous system, which serves to connect the CNS to limbs and organs. The heart and lungs are vital organs but belong to the circulatory and respiratory systems, respectively, rather than the nervous system. Veins and arteries are components of the circulatory system that transport blood throughout the body and are unrelated to the structure or function of the CNS.