Central nervous system
Central nervous system integrates and coordinates body activity.
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and the spinal cord, with the retina also technically part of the CNS. It is named so because the brain integrates received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. In vertebrates, the CNS is enclosed in the meninges and bathed in cerebral spinal fluid, and it is contained within the dorsal body cavity.
- field
- Anatomy and physiology
- known_for
- Integration of sensory information and coordination of body activity in bilaterally symmetric animals
Lore & Background
The central nervous system is a structure composed of nervous tissue positioned along the rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain, though precursor structures exist in onychophorans, gastropods and lancelets. The rest of the source article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals. In vertebrates, the brain and spinal cord are both enclosed in the meninges, which provide a barrier to chemicals dissolved in the blood, protecting the brain from most neurotoxins commonly found in food. Within the meninges the brain and spinal cord are bathed in cerebral spinal fluid. The CNS is composed of white and gray matter; white matter consists of axons and oligodendrocytes, while gray matter consists of neurons and unmyelinated fibers. Both tissues include a number of glial cells, which are often referred to as supporting cells of the CNS. The CNS consists of two major structures: the brain and spinal cord. The brain is encased in the skull, and the spinal cord is continuous with the brain and lies caudally to the brain, protected by the vertebrae. The spinal cord reaches from the base of the skull and terminates roughly level with the first or second lumbar vertebra. From and to the spinal cord are projections of the peripheral nervous system in the form of spinal nerves, allowing for voluntary and involuntary motions of muscles, as well as the perception of senses.
Reader's Guide
The central nervous system is of fundamental significance as the primary integration and coordination center for all multicellular animals except sponges and diploblasts. In vertebrates, it is radically distinct from other animals, being enclosed in the meninges and bathed in cerebral spinal fluid. The brain, as the major functional unit, processes information and controls body functions, while the spinal cord relays information to and from the brain and mediates reflexes. The CNS includes not only the brain and spinal cord but also the retina, optic nerve, olfactory nerves, and olfactory epithelium, the latter being the only central nervous tissue outside the meninges in direct contact with the environment, opening a pathway for therapeutic agents. The brainstem regulates vital functions such as blood pressure and breathing, while the cerebellum controls posture and coordination of movements. The presence of glial cells, including microglia and astrocytes, supports neuronal function and immune response. Understanding the CNS is crucial for comprehending neurological disorders, drug delivery, and the evolution of nervous systems across animal phyla.
Did You Know?
- The retina is technically part of the central nervous system.
- Only arthropods, cephalopods and vertebrates have a true brain.
- The olfactory epithelium is the only central nervous tissue outside the meninges in direct contact with the environment.
- The cerebellum holds more neurons than any other structure of the brain, including the larger cerebrum.
Frequently Asked Questions
What is the Central nervous system?
The CNS is the core control center of the nervous system, made up mainly of the brain and spinal cord, with the retina also counted as a component. It serves as the command hub for bilaterally symmetric, triploblastic animals.
What are the Central nervous system's powers/role?
Its primary job is to collect sensory input from the body, process that information, and then direct coordinated responses across all organ systems. Think of it as the conductor that keeps every part of the body working in sync.
Where does the Central nervous system sit in the body?
In vertebrates, the CNS is housed inside the dorsal body cavity, wrapped in protective meningeal layers and surrounded by cerebrospinal fluid that cushions and nourishes it.
Which animals actually have a Central nervous system?
Any bilaterally symmetric, triploblastic multicellular animal possesses one, which means essentially every animal except sponges and diploblasts like cnidarians.
Why is the Central nervous system important in animal anatomy?
Without the CNS, an animal could not integrate the flood of sensory data it receives or mount a unified, coordinated response to its environment. It is the single structure that ties the entire nervous system together into a functional whole.
More in Animal Anatomy 1-17
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