The central nervous system (CNS) and the peripheral nervous system (PNS) are the two main components of the nervous system, differing significantly in their location and function.
Central Nervous System (CNS)
The CNS is the command center of the body. It consists of the brain and the spinal cord. The brain processes information, controls bodily functions, and enables higher-level cognitive processes like thinking and reasoning. The spinal cord acts as a crucial relay, transmitting signals between the brain and the rest of the body. NCBI Bookshelf and Lumen Learning provide detailed information on the CNS structure and function.
Peripheral Nervous System (PNS)
The PNS is the extensive network of nerves that branches out from the CNS to connect it to the rest of the body. These nerves transmit sensory information from the body to the CNS and carry motor commands from the CNS to the muscles and glands. The PNS includes all the nerves that extend beyond the brain and spinal cord, reaching every part of your body, from your scalp to your toes. Cleveland Clinic describes the PNS as the communication network extending from the CNS. This includes the cranial nerves which connect directly to the brain.
Key Differences Summarized:
| Feature | CNS | PNS |
|---|---|---|
| Location | Brain and spinal cord | Nerves outside the brain and spinal cord |
| Function | Information processing, control center | Sensory input and motor output |
| Components | Brain, spinal cord | Cranial nerves, spinal nerves, ganglia |
| Myelination | Myelin structure differs from the PNS. | Myelin structure differs from the CNS. |
Examples:
- CNS: If you touch a hot stove, the sensory information of the heat is initially relayed to your CNS through PNS nerves for processing. The CNS then initiates a motor response to withdraw your hand via PNS nerves again.
- PNS: The feeling of a gentle breeze on your skin is detected by sensory receptors in the skin which send signals via the PNS to your brain (CNS).
Anatomically speaking, the CNS is made up of the brain and spinal cord; the PNS is made up of all the nerves travelling from the CNS to all the organs in your body, from the skin on your scalp to the tip of your toes.
