Animals perceive the world through their senses. Different species look through different sensory windows, so their views of the world are not the same. Dogs, for example, do not see color well, but they have far keener senses of hearing and smell than humans do. Thus while you watch a beautiful sunset, your dog is probably sniffing around the bushes and listening for the sounds of small animals in the underbrush.
Human hunters have exploited the remarkable sensory abilities of dogs for thousands of years. Most recently the hunt has extended to illicit drugs, smuggled contraband, bombs, and firearms. Dogs can be trained to detect the signature odors of such items, so they are used by police, customs agents, and other investigators to identify those odors wherever suspicious activities are likely to occur.
A black Labrador named Charlie (badge K9-001) was the first dog trained by the U.S. Treasury Department's Bureau of Alcohol, Tobacco, and Firearms to sniff out firearms and explosives. Charlie has sniffed out more than 200 illegal guns and 500 pounds of hidden explosives. With a nose that outperforms electronic sensors, Charlie helped solve a terrorist bombing case by discovering a tiny fragment of the bomb hundreds of yards from the site of the explosion. Charlie's nose is never off duty; on a recreational visit to a Civil War battlefield, it smelled out can-nonball fragments that had been buried for 130 years. ATF dogs receive expert training, but their careers are based on their remarkable sense of smell.
In this chapter, we will look at the general properties of sensory cells and see how they convert environmental stimuli to neuronal information. We will examine in detail the cells responsible for our senses and see how they are incorporated into sensory systems that provide the central nervous system with information about the world around and within us. In the course of our study of sensory systems, we will learn about the unusual sensory abilities of many other animals.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.