Getting to Know… The Central Nervous System By: Pam I.
We are all now connected by the Internet, like neurons in a giant brain. -- Stephen Hawking
I like nonsense; it wakes up the brain cells
-- Dr. Seuss
Michio Kaku, Professor of Theoretical Physics at City College of New York, says that “The human brain has 100 billion neurons, each neuron connected to 10,000 other neurons. Sitting on your shoulders is the most complicated object in the known universe.” So what is the best way to care for this “complicated object?” How can you keep your brain – and your whole nervous system, for that matter – working in tip-top shape? Are there foods you should or shouldn’t be eating? Or exercises you should be doing? With this new “Body Owner’s Manual,” you can learn all of these things and more. This first article covers the basics of your central nervous system. You’ll learn about the different parts of the system and what each part does. We’ll also bust some common myths about the brain and learn about optical illusions. Finally, we’ll set you up with some fun, interactive links that will allow you to explore the central nervous system in depth. Let’s get started!
Your Central Nervous System – The Basics
Your central nervous system (CNS) is made up of your brain and spinal cord. Basically, it is your body’s communication and control center, and it has a huge job. It does everything from keeping track of all your body’s functions, such as breathing, heartbeat, and digestion (even when you are asleep), to controlling actions like movement and speech.
Let’s take a closer look at each part of the nervous system, beginning with the brain. Your brain has several different parts and they all have different functions. The largest and most recognizable part of your brain is usually called the cerebrum, but can also be called the cortex. It is responsible for complex functions like thinking, talking, and moving. Your cerebrum is divided right down the middle (front to back) into two hemispheres, but it has four lobes: frontal, occipital, temporal, and parietal. The frontal lobe is responsible for emotions, reasoning, speech, and problem solving. The occipital lobe is the part of your brain that interprets vision. Your speech, perceptions, and memories are controlled by your temporal lobe. Finally, your parietal lobe controls recognition, movement, and body positioning.
There are a few more parts of the brain and central nervous system to cover. The cerebellum (also known as the “Little Brain”), is located below and at the back of the cerebrum. Its function is to maintain balance and fine muscle control. The brain stem is also a major part of the central nervous system and it takes care of a lot of your body’s more automatic activities, such as breathing, heartbeat, digestion and swallowing. It runs down from the brain and connects to the spinal cord, which stretches from the bottom of your skull to your tailbone. The spinal cord is the communication system between your brain and the rest of your body. Nerves connect to it and it transmits signals from all parts of the body to and from your brain. The corpus callosum connects the two hemispheres of the brain and basically lets them communicate with each other. Finally, the limbic system is actually made up of several different structures which we will not be covering in depth. However, the limbic system is incredibly important, since it is responsible for your moods. It controls your most basic drives (such as sex and hunger) and basic emotions (like happiness, fear, and anger).
Now that you know the major parts of the CNS, let’s look at the kinds of cells those parts are made of. You’ve probably heard about neurons, which are one of the cells that your nervous system uses to communicate with the rest of your body. Neurons are a major part of the brain and spinal cord. While most cells in the body are small, dendrites can be as long as a meter. The other type of cells you will often hear about are glial cells. There are different types of glial cells, but they all support the CNS in one way or another. Some protect neurons from damage while others perform functions such as phagocytosis, where they will clean up invading bacteria and viruses or damaged and dead neurons.
Now that you know some of the basic parts and functions of the nervous system, let’s bust some myths.
Myth # 1: You only use 10% of your brain.
This myth started in 1907 when William James, a psychologist, said “We are making use of only a small part of our possible mental and physical resources.” He was misquoted as saying that we only use 10% of our brains and the myth was born. According to brainfacts.org, while you are probably not using all of your brain at any one time, you use significantly more than 10%. Using brain scans, researchers have been able to learn that most activities use several different parts of the brain at once.
Myth # 2: You’re either left-brained or right-brained.
You’ve probably heard the saying that right-brained people are creative and left-brained people are good at science and math. While it is true that some functions, such as handedness, are largely controlled by one side of the brain or the other, all functions require input from both sides of the brain. Brainhq.com states that, the vast majority of the time, the two hemispheres of your brain work together to perform complex tasks like math, art, music, and science.
Myth # 3: You get more brain wrinkles when you learn new things.
This myth seems logical, since it’s been proven that people with more wrinkly brains tend to be more intelligent. During development in the womb, we start out with a smooth brain, but it develops all of its wrinkles before birth. The website howstuffworks.com writes that the human brain does change in response to what we learn, but the number of wrinkles stays the same throughout a person’s life.
Optical illusions are just what they sound like: Images that trick our eyes and brains into thinking we are seeing something we are not. There are three different kinds of optical illusions: literal, physiological, and cognitive. Literal optical illusions are like the first two pictures below, where the eye is actually seeing a picture that is right in front of them. Physiological illusions are things like bring flashes of light that leave imprints on your vision for a time. Imagine getting the sun flashed in your eyes. When you close them, you can still see the light for a time – a physiological illusion. Cognitive illusions are a little more difficult to define. Paintings by MC Escher are good examples of cognitive illusions. They work by distorting what you actually know about the physical world. See the dice picture below for an example.