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Thursdays at lunch is a busy but enjoyable time for me. I rocket home from the office (only three miles) and teach a one-hour class to a half dozen students who are part of our home school co-op. It's a great bunch of young people and the subject is a favorite of mine: human anatomy and physiology -- the amazing physical equipment we've been created with and how it works. There's a great verse from the Psalms that fits my feelings about this, "Great are the works of the LORD; They are studied by all who delight in them."

Since we'll be celebrating Thanksgiving this week, I want to turn from my usual focus on what can go wrong with our human equipment and take a few moments to appreciate how incredible it is. So let's take a few minutes and use our brains to think about and be thankful for our brains.

The human brain stores a lifetime of experiences, facts, and sensations while running an unimaginably complex organism, all the time adapting and changing to better fit its environment.

The average adult brain has about 100 billion neurons (nerve cells) which make trillions of links. In fact there are more neuron to neuron links in a single human brain than there are electronic links in all of the computer systems in the world. And we think the internet is so impressive! Each single cell of those 100 billion neurons has as much information stored in their DNA as approximately 2000 Encyclopedia Britannicas. Our brains work hard too. Although they make up only about 3 percent of the body's weight, it uses 20 percent of the body's blood supply due to its high need for oxygen and glucose.

So how does the brain work? To answer that well would take far more than a short newspaper column. But consider what happens when you step on a sharp thorn while walking barefoot in the grass. Exquisite little sensors in your foot are instantly triggered and they "call 911" by shooting a message up the nerves toward the brain at about 250 mph. The message is transmitted electrically by the turning on and off of countless molecular sodium and potassium pumps along the nerve. This in turns changes the charge around the nerve and these charges are transmitted up to the brain stem to nuclei where they communicate to just the right nerves which go to just the right muscles to tell them to contract so that you pull back your foot to avoid further harm. At the same time nerves to several other muscles in the other leg cause you to extend that leg to help the injured leg pull back. All this happens in a fraction of a second. Meanwhile your brain doesn't forget to keep your heart beating, your lungs breathing, your blood vessels at the right tension to maintain your blood pressure, and a few thousand other little tasks that your central nervous system (CNS) is overseeing at any given time. You may even get a little side message to your larynx to yell, "Ow" (hopefully nothing worse).

And that's the simple stuff. What about dreams, sometimes in full color? What about vivid memories brought back with all their emotion with a whiff of a wood fire or a flock of geese soaring overhead or water lapping against the shore of a lake? What about the brain's ability to turn photons (light particles) bouncing off a two dimensional retina into colorful three dimensional images of our world? What about affections of love, beauty, joy? What about music?

I am one of those who, despite years of naturalistic teaching, cannot see any way that this miraculously brilliant servant housed inside our skull could be the product of unaided, unintelligent dead matter... matter which itself somehow sprang out of precisely nothing. So this Thanksgiving, and hopefully in between Thanksgivings, I hope we will use not only our brains but every part of our being to give thanks to the Creator of every good (and amazing!) thing.

Dr. Andrew Smith is board-certified in family medicine and practices at 1503 E. Lamar Alexander Parkway, Maryville. Contact him at 982-0835.