Neural Tissue

Neural Tissue

After studying this chapter, readers should be able to:

1. Describe the anatomical and functional divisions of the nervous system.

2. List the basic functions of the nervous system.

3. Describe the functions of astrocytes and oligodendrocytes.

4. Describe the neuron and its important structural components.

5. Describe the locations and functions of neuroglia.

6. Describe synapses and synaptic transmission.

7. Discuss the events that occur at a chemical synapse.

8. List the major types of neurotransmitters.

9. Define action potential.

10. Explain the classifications of nerve fibers.

Overview

The nervous system controls all other body systems and the communications between all body components. It is involved with actions, emotions, and thoughts. Chemical and electrical signals are used in cellular communication. They occur very rapidly, with specific goals, and responses to these signals are almost immediate. The unit upon which all nervous system activity is based is known as the neuron (nerve cell). Neurons require neuroglial cells (neuroglia), which conduct phagocytosis, fill spaces, produce compo-nents of myelin, and provide structural frameworks. There are many more neuroglial cells than neurons in the body. Neuroglia, which exists in both the central nervous system (CNS) and peripheral nervous system (PNS), can divide, whereas most neurons cannot. Neuroglia are much smaller than neurons and their nuclei stain dark. There are approximately 10 CNS neuroglia to every one neuron. Neuroglia form approximately half the mass of the brain. Neuroglia are classified as astrocytes, ependymal cells, microglial cells, and oligodendrocytes. In the PNS, the two types of neuroglia are satellite cells and Schwann cells.