Central and Peripheral Nervous System Figure 1. The structures of the PNS are referred to as ganglia and nerves, which can be seen as distinct structures. Depending on different aspects of the nervous system, the dividing line between central and peripheral is not necessarily universal. The peripheral nervous system is so named because it is on the periphery-meaning beyond the brain and spinal cord. In actuality, there are some elements of the peripheral nervous system that are within the cranial or vertebral cavities. It is a bit of an oversimplification to say that the CNS is what is inside these two cavities and the peripheral nervous system is outside of them, but that is one way to start to think about it. The brain is contained within the cranial cavity of the skull, and the spinal cord is contained within the vertebral cavity of the vertebral column. The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else (Figure 1. The nervous system can be divided into two major regions: the central and peripheral nervous systems. The Central and Peripheral Nervous Systems In comparison, it is easy to see that the stomach is different than the esophagus or the liver, so you can imagine the digestive system as a collection of specific organs. It is as if the nervous system is composed of many organs that all look similar and can only be differentiated using tools such as the microscope or electrophysiology. Within the brain, many different and separate regions are responsible for many different and separate functions. That suggests it is made of two organs-and you may not even think of the spinal cord as an organ-but the nervous system is a very complex structure. The picture you have in your mind of the nervous system probably includes the brain, the nervous tissue contained within the cranium, and the spinal cord, the extension of nervous tissue within the vertebral column. List the basic functions of the nervous system.Relate the functional and structural differences between gray matter and white matter structures of the nervous system to the structure of neurons.
Identify the anatomical and functional divisions of the nervous system.Basic Structure and Function of the Nervous Systemīy the end of this section, you will be able to:
But before you learn about that, you will see a big picture of the system-actually, a few big pictures. The focus of this chapter is on nervous (neural) tissue, both its structure and its function. In other chapters, the finer details of the nervous system will be explained, but first looking at an overview of the system will allow you to begin to understand how its parts work together. One easy way to begin to understand the structure of the nervous system is to start with the large divisions and work through to a more in-depth understanding. But our current level of understanding is probably nowhere close to that limit. It is an interesting conundrum to consider that the complexity of the nervous system may be too complex for it (that is, for us) to completely unravel. That quote is from the early 1990s in the two decades since, progress has continued at an amazing rate within the scientific disciplines of neuroscience. Kramer’s book Listening to Prozac, a pharmaceutical researcher is quoted as saying, “If the human brain were simple enough for us to understand, we would be too simple to understand it” (1994). The nervous system is a very complex organ system.
Name the parts of the multipolar neuron in order of polarity.Describe the functional and structural differences between gray matter and white matter structures.Name the major divisions of the nervous system, both anatomical and functional.After studying this chapter, you will be able to: