Anatomy and physiology · BEGINNER LESSON
Central nervous system
The central nervous system (CNS) is the part of the nervous system made up of the brain and spinal cord. It acts as the main processing center for body information and responses.
What it is
The central nervous system, or CNS, is the brain and spinal cord. It sits in the cranial cavity of the skull and the vertebral cavity inside the spine, so it is protected by bone and also by connective tissue membranes called meninges and by cerebrospinal fluid (CSF), a fluid that cushions the nervous tissue. The brain is continuous with the spinal cord at the foramen magnum, the opening at the base of the skull. [1,2,0]
[2] Central nervous system: MedlinePlus Medical Encyclopedia [3] Chapter 8 Central Nervous System - Nursing Pharmacology [1] training.seer.cancer.gov › anatomy › nervousThe Central Nervous System - SEER Training
Main parts and how they connect
The brain is commonly divided into the cerebrum, diencephalon, brain stem, and cerebellum. The cerebrum is the largest part and its two halves are linked by the corpus callosum, a band of white nerve fibers that allows communication between them. The diencephalon includes the thalamus, hypothalamus, and epithalamus; the thalamus relays most sensory signals to the cerebral cortex, which is the outer layer of the cerebrum. The brain stem, made of the midbrain, pons, and medulla oblongata, carries nerve fibers between higher brain centers and the spinal cord. [0]
[1] training.seer.cancer.gov › anatomy › nervousThe Central Nervous System - SEER Training
What the spinal cord does
The spinal cord extends from the foramen magnum to about the first lumbar vertebra and is divided into 31 segments, each giving rise to a pair of spinal nerves. It has two major roles: it conducts sensory signals upward to the brain through ascending tracts and carries motor signals downward through descending tracts. It also serves as a reflex center. A reflex arc is a nerve pathway that produces a fast automatic response without conscious thought, such as withdrawing from pain before the person is fully aware of it. [0]
[1] training.seer.cancer.gov › anatomy › nervousThe Central Nervous System - SEER Training
How CNS communication works
Nervous-system communication often uses electrical impulses that trigger release of a neurotransmitter, a chemical messenger that binds to a receptor on another cell. In a chemical synapse, the neurotransmitter crosses a tiny gap called the synaptic cleft and binds to a matching receptor; in an electrical synapse, ions pass directly between cells. These signaling details help explain why the CNS can process information and coordinate body functions. [2]
Limitations and evidence notes
The CNS is essential, but its exact mechanisms are not always fully understood. The supplied sources note that neuroscience still has limits, and some drug actions in the CNS are described as unknown. Also, the boundary between the CNS and the peripheral nervous system is useful for learning, but it is not perfectly simple in every case. [2]
SEE THE IDEA
Central nervous system overview
Processes information; includes cerebrum, diencephalon, brain stem, and cerebellum.
Carries signals to and from the brain and can produce reflexes.
Bone, meninges, and cerebrospinal fluid surround the CNS.
Neurons use impulses, neurotransmitters, and synapses to pass signals.
Brain and spinal cord form the CNS; protection surrounds them, and signaling between their cells supports processing and response.
A simple view of what the CNS includes, how it is protected, and how it communicates.
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Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.