Nervous System

The Vertebrate Nervous System:
1 - receives stimuli from receptors & transmits information to effectors that respond to stimulation
2 - regulates behavior by integrating incoming sensory information with stored information (the results of past experience) & translating that into action by way of effectors
3 - includes billions of nerve cells (or neurons), each of which establishes thousands of contacts with other nerve cells
4 - also includes neuroglia cells that support, nourish, & insulate neurons

Subdivisions of the Vertebrate Nervous System:
1 - Central Nervous System - including the brain & spinal cord
2 - Peripheral Nervous System - including cranial nerves, spinal nerves, & all branches of cranial & spinal nerves

Neurons (or nerve cells):
respond to stimuli & conduct impulses
3 types - all with cell body & processes (axons & dendrites):
multipolar
bipolar
unipolar

Spinal cord:
located in vertebral canal
anatomical beginning is the foramen magnum of the skull
length varies among vertebrates:
in vertebrates with abundant tail musculature, the spinal cord extends to the caudal end of the vertebral column
in vertebrates without tails or without much tail musculature, the spinal cord extends to about the lumbar region of the vertebral column
a cross-section of the spinal cord reveals gray matter & white matter. The gray matter consists of nerve cell bodies, while the white matter consists of nerve cell processes (axons). These processes make up ascending (sensory) and descending (motor) fiber tracts.