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Major Organs and Divisions of the Nervous System

  • The nervous system is anatomically and functionally partitioned into the central nervous system and peripheral nervous system.
  • Making up the central nervous system (CNS) are the image descriptionbrain and image descriptionspinal cord, which serve as the body’s assessment and control center.
An image of the body showing the head and the back of a smiley man
An image of the body showing the Brain, head and the back of a smiley man, the brain is labeled
An image of the body showing the Spinal cord, Brain, head and the back of a smiley man, the Spinal cord and the brain are labeled
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  • These vital organs are surrounded and protected by the bones of the skull and vertebral column.
  • The peripheral nervous system (PNS) is formed by a network of image descriptionnerves that extend throughout the body.
An image of the body showing the Spinal cord, Brain, head and the back of a smiley man, the Spinal cord and the brain are labeled
An image of the body showing the Nerves (PNS), Spinal cord, Brain, head and the back of a smiley man, the Nerves (PNS), Spinal cord and the brain are labeled
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An image showing a lower view of the brain and the cranial nerves
An image showing a lower view of the brain and the cranial nerves (labeled)
An image showing a spinal cord segment (gray and white matters and nerves coming out)
An image showing a spinal cord segment (gray and white matters and nerves coming out) , the spinal nerve is labeled
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  • Inside the nerves are the image descriptionaxon processes of numerous nerves cells (or neurons).
An image showing a nerve section which connects between the CNS and organs
An image showing a nerve section which connects between the CNS and organs, the axon process of a neuron is labeled
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  • The wire-like axons run the length of the nerves and are grouped by connective tissue into cylindrical bundles called image descriptionfascicles (L. fasciculi).
An image showing a nerve section which connects between the CNS and organs
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An image showing the action potential moving though a sensory nerve, from the organs to the CNS

An image showing the action potential moving though a motor nerve, from the CNS to the organs

  • Most nerves are  image descriptionmixed, meaning they contain both motor and sensory neurons.

An image showing the action potential moving though a mixed nerve, from the CNS to the organs (Motor) AND from the organs to the CNS (Sensory)

  • Based on their functions, the neurons in nerves divide the peripheral nervous system into somatic and autonomic nervous systems.

An image showing the basic types of the Nervous system (CNS and PNS) and their subtypes

  • Somatic neurons carry signals that allow the CNS to consciously monitor the external environment and control body movements. In contrast, autonomic neurons carry signals that allow the CNS to subconsciously regulate the body’s internal environment and control the activity of the soft organs (viscera).