The brain is a marvel that only God can ever fully understand. Our brain controls our emotions, sleep cycles, digestion, heart rate, breathing, and movement. Our brains are who we are and everything we will ever be. Only in being filled with the Holy Spirit would we ever transcend this. Our first parents’ brains were undoubtedly more complex and certainly more efficiently used than our own today. Someone once said: “The brain is a wonderful organ. It starts working the moment you get up in the morning and does not stop until you get into the office.” I know that many of us can relate to that, including myself. A popular myth is that we use only ten percent of our brains. This myth may be due to a misquote of Albert Einstein, but there is no scientific evidence that backs up this myth.
Of the vast information on the brain, one thing we do understand is that it controls all of our body’s functions as well as being the seat of the mind. This was not always known, however. Aristotle, the Greek philosopher, believed that the heart, not the brain, was the location of thought and intelligence. The ancient Egyptians also did not have much respect for this organ as seen when making a mummy. The brain was removed and discarded, whereas the heart and other organs were carefully preserved.
The nervous system is made up of the brain, spinal cord, and the nerves. The main cell that makes up nervous tissue is the neuron. It is estimated that there are 100 billion neurons in the brain. To better understand this number, let us think of it in other terms. Neurons come in different sizes, but for the sake of this illustration we will say that they are ten microns wide. If you placed 100 billion neurons in a line, the line would be invisible but it would stretch to 100 km (62.14 miles).
The brain and spinal cord are bathed in a circulating fluid called the cerebrospinal fluid or CSF. CSF acts as a shock absorber as well as a diffusion medium for nutrients, special chemicals, and waste products. Blood vessels circulate blood through the brain, just as anywhere else in the body. Amazingly, however, chemicals dissolved in the blood do not have free access to the brain. Cells called endothelial cells line blood vessels in the brain and control the chemical exchange between the blood and the fluid surrounding brain cells. This is called a blood-brain barrier, isolating the central nervous system (CNS) from the general circulation. God knows how to protect the delicate but marvelously intricate processes of the CNS.
The function of the nervous system, in general, is to gather information, store data and control the body’s systems. The nervous system collects information about the conditions in relation to the body’s external state and analyzes this information. The information is then used to initiate appropriate responses. Simplistically, you put your hand on the burner of a stove, the brain determines “stove is hot—hot is bad!” Your hand is removed from the burner. All of this occurs much more quickly than you just read it. Information travels along nerves at speeds up to 120 meters/second or 268 mph.
The nervous system uses electrical impulses, which travel along the length of the neurons, as well as chemicals called neurotransmitters. The endocrine system has its own method of data transfer using hormones, but unlike the nervous system, it may take many hours to respond with hormones.
All intellectual functions are the major function of the cerebrum, which is the largest portion of the brain. Have you ever heard of a person who is brain dead? That means that they no longer have brain waves that translate into thought, but the physical control center, the brain stem, is still functioning enough to keep the body alive. Yet the higher functions of thought and emotion are closely interlinked with the physical functions. “The senses . . . are the avenues to the soul.” Healthful Living, 193
Like the rest of the body, the nervous system requires adherence to the laws of health to function optimally. Ellen White said, “The brain is the organ and instrument of the mind, and controls the whole body. In order for the other parts of the system to be healthy, the brain must be healthy. And in order for the brain to be healthy, the blood must be pure. If by correct habits of eating and drinking the blood is kept pure, the brain will be properly nourished.” Medical Ministry, 291. She also understood that there is a balance between physical exercise and mental exercise that must be maintained. We can all understand that we need to study to learn, but on the other side of the coin, “The exercise of the brain in study without corresponding physical exercise has a tendency to attract the blood to the brain, and the circulation of the blood through the system becomes unbalanced. The brain has too much blood and the extremities too little.” Healthful Living, 180.
Even when all of our nervous system’s hardware and software is working correctly, we do not always use it properly. In the nineteenth century, Ambrose Bierce said that the definition of a cabbage is “A familiar kitchen-garden vegetable about as large and wise as a man’s head.” This is too often true isn’t it? I would have to say that without the Lord’s guidance it is always true. David’s insight was that “A fool uttereth all his mind: but a wise [man] keepeth it in till afterwards.” Proverbs 29:11. A current saying puts it this way: “Lord, keep Your arm around my shoulder and Your hand over my mouth.” Indeed!