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How do the central nervous system and peripheral nervous system differ?
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nervous system
In a myelinated axon, the myelin sheath prevents the local current (small black arrows) from flowing across the membrane. This forces the current to travel down the nerve fibre to the unmyelinated nodes of Ranvier, which have a high concentration of ion channels. Upon stimulation, these ion channels propagate the action potential (large green arrows) to the next node. Thus, the action potential jumps along the fibre as it is regenerated at each node, a process called saltatory conduction. In an unmyelinated axon, the action potential is propagated along the entire membrane, fading as it diffuses back through the membrane to the original depolarized region.
The central nervous system (CNS) and the peripheral nervous system (PNS) differ primarily in their anatomical location and functional roles within the human nervous system.
Anatomical Differences
- Central Nervous System: The CNS consists of the brain and spinal cord. It is positioned along the body's midline and is protected by the skull and vertebral column.1
- Peripheral Nervous System: The PNS comprises all neural structures outside the brain and spinal cord, including spinal nerves, cranial nerves, and parts of the autonomic nervous system.12
Functional Differences
- CNS: Acts as the primary processing center. It receives sensory input, coordinates responses, regulates voluntary and involuntary movements, and serves as the seat of emotion and cognition.1
- PNS: Functions as a communication channel. It relays sensory signals from the body to the CNS and transmits motor responses from the CNS to muscles and glands.12