On
Tuesday, August 16, 2005, scientists at the University of Edinburgh's
Institute for Stem Cell Research and the University of Milan announced
that they created the world's first pure nerve stem cells from human
embryonic stem cells.
The scientists were able to do this using a new technique to grow pure
brain stem cells. The hope is that this method can be used to model
diseases of the nervous system—like Alzheimer's and Parkinson's—and
develop new drugs to treat these debilitating diseases.
The nervous system is vital to every day life, because it's your body's
primary control system. It's what we depend upon for controlling our
muscles, smelling aromas, noticing if something is too hot to touch,
remembering to feed our pets, and so forth.
That's why people who have developed diseases that affect the normal
functioning of the nervous system have trouble controlling their movements,
for example, often making their limbs and heads shake. Such diseases
also often affect a person's ability to remember things.
To get a better understanding of how the nervous system works, this
week you'll discover how the brain, spinal cord, and network of nerves
interact and respond to stimuli, allowing humans and other animals to
move around, make decisions, eat and digest our food, etc.
Nervous System Basics
The
Nervous System is essentially composed of three parts: the brain, the
spinal cord, and your network of peripheral nerves.
It's the nerve cells that are integrated into things like your organs
and muscles.
So to begin, let's Probe
the Brain at PBS to look at how the brain is linked to muscle
movement.
Using your Shockwave Player, go directly to the Probe the Brain
activity.
Click on any point of the tan-colored strip in the brain. When the
label pops up, click the place where the line points and watch that
particular body part flinch. Also, note how each side of the control
point is linked to the opposite side of the body.
To dig a little deeper, let's take a Virtual
Body Tour at MerckSource.
Open the Interactive Body Guide, click to begin the module,
then explore the Nervous system.
Read the Introduction, and then continue through the CNS: neurons,
brain, spinal cord, the PNS: somatic and autonomic nervous systems,
and the Sense organs.
What are the primary functions of the nervous system? What does "electrochemical"
mean? What's the difference between the CNS and PNS? What roles do dendrites
and axons play? What about sensory receptors, sensory neurons, and motor
neurons?
How would you describe the role of the somatic nervous system? How
does that compare to the autonomic?
In the Lab
So,
how do scientists, like those working with the nerve stem cells, learn
about how nerve cells and the nervous system work?
Well, much is done through experimentation in a laboratory with chemistry
and animal test subjects. This type of science that explores the Nervous
System is called neuroscience.
With the basics now under your belt (or tucked under your lab coat),
you're ready to step into the Neuroscience
Virtual Lab at the Howard Hughes Medical Institute. Here, you'll
conduct some of your own experiments, to see how one animal, the leech, reacts
to varying stimuli.
Click to enter the lab, then read the Objective and browse through
the backgrounds about the Leech, the Nervous System, and
the Electrical Equipment. Make sure to review the concept of
Resting Potential and Action Potential in the Nervous System background
section.
What characteristics make the leech a good test subject? What is the
difference between the resting potential and action potential?
What exactly will the equipment measure during the experiment? How
does that relate to the resting and action potentials? How exactly does
an oscilloscope work, and what does it tell you?
Why would you want to place the dissected tissue in a bath of salt
water? What kind of control reference do you use for the experiment,
and why is doing that an important step?
Before
starting the experiment, make sure to review your virtual tools, using
the tabs along the top - Notebook, Atlas, Glossary,
and Equipment.
Begin the lab, starting with the Overview of equipment used in the
lab. Continue through the procedure by following the on-screen
instructions.
You'll anesthetize and dissect the leech, then remove the leech innards
and observe the ganglion. Cut out the ganglion window, isolate one ganglion,
cut the ganglion sinus, then probe and identify the ganglion sensory
cells.
Choose a cell, then treat it with each of the different tools: forceps,
probe, and feather. After stimulating with each tool, click Dye Injection
and then UV Switch to look inside the cell to see what kind of pathway
the electrical charge took.
After testing one cell, use the Atlas to help you identify the
cell type.
Test Another Cell and repeat the procedure several more times.
Why exactly did you cut open the leech's sinus? How do the different
stimuli affect the different nerve cells? What do you think might happen
to an organism if individual nerve cells or points along neurological
pathways were impaired?
What kinds of resources do you think are needed to conduct these types
of experiments? Who do you think performs neuroscience research and
for what purpose?
