2. Organization of Nervous System
The nervous system has 2 main divisions:
- Central nervous system – the brain and the spinal cord. The primary function of the CNS is the integration and processing of information.
- Peripheral nervous system – the nervous tissue outside of the CNS (i.e., outside of the dorsal body cavity). Spinal nerves carry information between the tissues and the spinal cord while cranial nerves carry information between the tissues and the brain.
The PNS is subdivided into the:
- Sensory afferent division – cells carrying information from sensory receptors to the CNS.
- Motor efferent division – cells carrying commands from the CNS to the effector organs.
The motor efferent division of the PNS is further subdivided into the:
- Somatic nervous system – cells sending signals from the CNS to skeletal muscles.
- Autonomic nervous system – cells sending signals from the CNS to smooth muscle, cardiac muscle, and glands
The ANS is further subdivided into a
- Sympathetic division (the “fight or flight” division) and a
- Parasympathetic division (the “rest and digest” division).
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Organization of Nervous System