Anatomy and Physiology: The Nervous System
The Nervous System
As the other control system, after the endocrine, the nervous system carries a great burden. It must be able to make rapid changes in the body and regulate the environment at all times. Not content to borrow the pathways of the cardiovascular system, the nervous system has its own elaborate pathways, often running roughly parallel to the blood vessels.
The response is so fast that there is no appreciable difference in reaction time, regardless of height. The great distances the messages often travel require certain tricks to speed up the nerve impulse. Time savers, such as which messages need to go all the way to the brain and which don't (such as reflexes), are part of the solution. These topics and more are discussed in this section.
Excerpted from The Complete Idiot's Guide to Anatomy and Physiology © 2004 by Michael J. Vieira Lazaroff. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.