2.1: Introduction
- Page ID
- 151215
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To physically take something apart is a great way to learn about the relationship between structure and function. Engineers and electricians use schematics to help them figure out what parts connect to where, and architects may use blueprints to aid them in the creation of a building. You can learn a lot about a system by understanding the function of the individual components and how they interact with one another. The whole is often greater than the sum of their parts, and a failure of one part to perform its duty can have wide reaching consequences.
The nervous system is one of the most complex systems that we know of. Parts of this system malfunction frequently, and the results are a wide range of neurological disorders that affect humans, from injury to genetic disorders.
The gross anatomy of the nervous system is an important foundation to the studies of other aspects of neuroscience. This chapter covers some of the major anatomical structures in the nervous system, starting with the brain, working down the spinal cord, all the way out to nonnervous tissue. The end of this chapter will also cover the many support structures that allow the nervous system to carry out their jobs.
Broadly speaking, the nervous system can be divided into two main categories: The central nervous system (CNS) and the peripheral nervous system (PNS). Simply put, the CNS is the brain and spinal cord, while the PNS is all the other nerve cells in the body. The two systems are not isolated from each other; information passes rapidly between the PNS and the CNS, and vice versa. When a signal that originates in the PNS moves to the CNS, we sometimes say that the signal is incoming or ascending, while the CNS to PNS direction is outgoing or descending. Information that arrives into the CNS is also called an afferent signal, while information leaving the CNS is an efferent signal. These two terms are frequently confused, but you can use the knowledge of other words that start with “e” to remember that an “exit” or an “escape” is something that moves away. Alternatively, an efferent signal is something that has an effect on the outside world, while an afferent signal affects the person.
