Dance of the Senses

What am I looking at?

This image shows a sensory neuron from the embryo of a rat. The bulb at the center is the neuron’s cell body (1). The fringe around the cell body is composed mainly of dendrites (2). The different colors represent the location of various proteins in the cell that help it perform its function of gathering information from the environment.

Biology in the background

Sensory neurons are the cells of the nervous system that gather information from the environment and send it to the spinal cord, and in most cases on to the brain. While there are many different types of sensory neurons, most have dendrites that extend from the cell body and detect changes in specific parameters of the environment – such as mechanical force, the presence of ions, etc. Sensory neurons can detect many kinds of information, including touch, heat, cold, pain, pressure, and much more.

Most sensory neurons are specialized to react to a specific change in the parameters of their environment, external or internal, although some cells have receptors that can detect two types of stimuli. For example, heat receptors in your mouth also happen to bind capsaicin, the molecule that gives chili peppers their bite, which is why your tongue feels like it’s on fire when you munch on a habanero. Similarly, cold receptors respond to menthol, which is why it feels like a cool breeze in your mouth when you eat a mint or brush your teeth with mint-flavored toothpaste.

The cell bodies of these neurons can vary in size a great deal, but they generally range from 30 to 50 micrometers across, or roughly half the width of a human hair.

Technique

This image was created using fluorescence microscopy.