Unit 5 – Introduction to Nervous System Tissues

Introduction to Nervous System Tissues

The nervous system is responsible for controlling most body functions by continually processing sensory information and coordinating appropriate responses to maintain homeostasis.  The nervous system includes a variety of different organs and tissues including the brain, spinal cord, spinal nerves, peripheral nerves, enteric nerves, sensory organs and receptors, and the blood vessels, connective tissues, and nervous system helper cells (known as neuroglia) that support, protect, and assist normal function.

The human nervous system is divided anatomically into three major divisions known as the central nervous system (CNS), enteric nervous system (ENS), and peripheral nervous system (PNS).  The central nervous system is comprised of the brain and spinal cord including all the neuroglia, connective tissues, and blood vessels that support their normal activities.  The enteric nervous system is a system of nerves that primarily control the involuntary activities of the digestive tract.  Note that some textbooks and neuroscientists simply consider the enteric nervous system a part of the peripheral nervous system.  The peripheral nervous system includes all nervous tissue found outside the central nervous system and enteric nervous system such as spinal nerves, peripheral nerves, and sensory organs and receptors.

The primary functional cells of nervous system tissues are neurons (nerve cells) which are specialized for transmitting communication signals known as action potentials.  Also associated with nervous system tissues are a variety of nervous system helper cells known as neuroglia that help protect and support normal neuron function.

This unit covers the basic histology of a few selected nervous system organs, tissues, and cells.  Specifically, there is a chapter dedicated to each of the following: the cross-sectional organization of the spinal cord, the structure of peripheral nerves, the basic structure and function of multipolar neurons, and the basic structure and function of astrocytes which are a type of neuroglia found in the CNS.  Also included in this unit is a chapter that covers the basic structure and function of neuromuscular junctions (also found in Unit 5) and a chapter that provides numerous nervous system tissue quizzes and interactive learning activities.