Neurons: Cells That Produce Electrical Current
Nerves interpenetrating our bodies consist of hundreds, and sometimes, thousands of nerve cells called "neurons." An average neuron is 10 microns wide.4(One micron is equal to 1/1000 millimeter, which equals 0.000039 of an inch.) Were we able to line up the 100 billion neurons in a human brain, their line would extend for a full 100 kilometers (62 miles). But this line would be only 10 microns wide, invisible to the naked eye. You can envisage the minute size of neurons with the following comparison: 50 neurons would fit into a period at the end of this sentence 5and 30,000 on the head of a pin. 6
Neurons have been created to carry the electrical impulses throughout the body. The task of most neurons is to receive signals from neighboring neurons and then to transmit these on to another adjacent neuron or to the ultimate target cell. Neurons communicate with one another, carrying out thousands of these processes every second.
We can compare a neuron to an electrical switch that goes on or off, depending on circumstances. On its own, a neuron constitutes only a very small part of the interconnected circuits of the nervous system. But in the absence of these tiny electrical circuits, life is impossible. Professor Werner Gitt of the German Federal Institute of Physics and Technology describes this giant complex squeezed into this small area:
If it were possible to describe [the nervous system] as a circuit diagram, [with each neuron] represented by a single pinhead, such a circuit diagram would require an area of several kilometers. . . . [It would be] several hundred times more complex than the entire global telephone network.7
As he emphasizes, the nervous system in our bodies functions like a very complex data network, which depends on all the neurons performing their duties to perfection. With the rhythmic, coordinated motion of the impulses from one neuron to the next, each organ, muscle, joint, system and cell performs its functions without any conscious command or supervision from you.
Moreover, although millions of cells die in your body every day, these are expelled from your body in a way that causes no disruption to its balances and functions. Again by means of an impeccable system, new cells replace the ones that have died. In this, there is not the slightest error in terms of timing or measurement. We have no control over these activities, and continue to enjoy healthy lives so long as none of them suffer any disruption.
If you tread on a piece of broken glass while walking barefoot, only a few thousandths of a second elapse between the glass entering your foot and your brain perceiving the pain. During that interval—so brief that it is impossible for you to be aware of it—a message is sent from your foot to your brain, a rapid and flawless communication carried out by neurons. In this way, you lift your foot off the ground before it can be injured any further.
It is completely beyond the bounds of possibility for such a system to have developed spontaneously. However, certain circles who blindly support the theory of evolution seek to account for this perfect order in the human body in terms of random coincidences. We can show just how meaningless these claims are with the following example:
Look at the electrical devices around you, each of which has been specially designed with plastic and electronic equipment, buttons, cables and other components for a specific objective that will make your life easier. Dozens of engineers have worked behind the scenes for a single hairdryer, along with the use of various plants, several branches of science and the designs of experts in the field. The result was a device that's functional and easy to use. No rational person could logically suggest that such a device came into being as the result of chance.
Your body, however, possesses an electrical system far more complex than that in any electrical device. The odds against such a system coming into being by chance are therefore still more infinitesimally remote.
Neurons Specially Created To Carry Signals
All neurons contain a nucleus, short fibers known as dendrites that carry electrical signals, and a long fiber known as axon that carries signals for long distances. The nerve cell, which can be as fine as silk thread, can be as long as roughly 1 meter (3,2 feet). Signals sometimes must travel even greater distances along the nerves.8
It’s fair to liken the body of the neuron to a telephone switchboard equipped with advanced technology. However, with its cellular dimensions varying between 0.004 and 0.1 millimeters (0.0001575 and 0.003937 of an inch) and wide-ranging communication mechanisms, this miniaturized telephone exchange has no equivalent in the modern world. In contrast to other cells, neurons contain both dendrites and axons, which give rise to lines of communication that permit the cell to pass its signals along to others. Dendrites receive messages, and axons send them.
A neuron can send an impulse in as little as 1/1,000 of a second. This means that a single neuron can transmit 1,000 nerve signals a second. In general, however, transmission may range between 10 and 500 impulses per second. 9The largest and thickest nerve fibers transmit electricity at a speed of 152 meters (500 feet) per second, and the thinnest of them at about 1 meter (3 feet) a second. 10
Information is transmitted without impairment inside the neuron and forwarded to the correct destination in a most astonishing way. However, the speed at which these phenomena take place is no less astonishing.
Imagine that all the complex systems in your body exist, but that the data transmission in your nerve cells is slower than it actually is: Only hours after the event could you appreciate the beauty of a view, the taste of the food you ate, or that something you touched was hot enough to burn your fingers. You would need dozens of minutes to reply to a question put to you. Crossing from one side of the street to another, or driving, lifting a fork to your mouth, commenting on an article of clothing you like, and countless other forms of behavior could lengthen into situations seriously incompatible with your lifestyle, or which even endangered your life. Lapses in timing between an event you perceive and being able to speak might make life untenable. Furthermore, this example only considers actions that we undertake voluntarily. The body also performs activities outside our conscious control, such as the beating of the heart. Any slowing in the signals regarding these functions would have fatal consequences. However, through the blessing of our Lord, the Compassionate and Merciful, everything in the human body is just as it needs to be.
In one verse of the Qur’an it is revealed that Allah has created all things in their proper measure:
Allah knows what every female bears and every shrinking of the womb and every swelling. Everything has its measure with Him. Allah knows what every female bears and every shrinking of the womb and every swelling. Everything has its measure with Him.
Dendrites and Axons: The Cables That Surround Our Bodies
Dendrites consist of a large number of short protrusions and are comparable to the roots of the cell. With their branched structure, dendrites receive reports arriving from other neurons and transmit these to the cell body. Put another way, dendrites are like electrical cables, transmitting signals entering the cell. Every neuron possesses up to 100,000 branching dendrites that carry incoming messages to the cell.11
The axons generally bring information from sense receptors to the brain and spinal cord or transmit commands back to the muscles, glands and internal organs. An axon is a long fiber, generally consisting of a single protrusion, that emerges from the cell body and along which signals are sent. Individual axons are microscopic in diameter - typically about one micrometre across (1μm) - but may extend to macroscopic (>1mm) lengths. The longest axons in the human body, for example, are those of the sciatic nerve, which run from the base of the spine to the big toe of each foot. These single-cell fibers of the sciatic nerve may extend a meter or even longer.12
Another striking feature is that a single axon is capable of dividing itself into as many as 10,000 terminals, or end sections. In this way, each terminal can be connected to a different neuron and can permit more than one region to be stimulated at the same time. Since any one single neuron can receive signals from more than 1,000 other neurons, it can carry a million different pieces of information at the same time. 13—an incredible figure. This ability plays a very important role in situations wherein more than one muscle fiber needs to be activated. With these structures, each nerve cell appears like a dense network consisting of long chains.
If the nerves did not have such a structure, then every signal would have to be transmitted in turn. That would slow and seriously impair the rapid, complex transfer of signals in the body.
We can compare the axon terminals at the end of dendrites to plugs fitting into sockets. Thus, in the same way that an electrical current flows from the socket to the plug, the electrical signal continues on between two nerve cells. These connection points at the axons’ ends are attached to receptors on other cells and permit information to transmit between cells. In the way they allow communication between different points in the nervous system, axons are comparable to the links connecting one part of an electrical circuit to another.
Each of these features is essential for our bodies’ communication and coordination. Our ability to lead healthy lives and our very existence depend on all these details functioning flawlessly. One of the aims behind their creation is to exhibit the knowledge and artistry of our Lord. Ours is the responsibility to appreciate the greatness of our Lord and give proper thanks:
. . . Allah pours out His favour on mankind but most people do not show thanks. That is Allah, your Lord, the Creator of everything. There is no god but Him--so how have you been perverted? (Surah Ghafir: 61-62)
The Role of The Synapses in Data Transmission
The gaps or spaces between the axons of two neurons are known as synapses. Communication between the two neurons is established and maintained at these terminal connection points. In the same way that a telephone switchboard permits a large number of callers to talk to one another at the same time, so a neuron can communicate with many other neurons by means of these synapses. Each neuron has around tens of thousands of synapses, 14 meaning that a neuron can establish connections with tens of thousands of separate nerve cells. Even assuming that hundreds of millions of telephone conversations could be transmitted over a single telephone network at the same time, this capacity still lags far behind that of the human brain, which can effect 1 quadrillion (1,000,000,000,000,000) communications by means of the synapse inside it.15Consider how hard-pressed one human being is when working on a 10-line telephone switchboard! You can better understand how a single nerve cell simultaneously carrying out 10,000 connections is evidence of an extraordinary creation.
A neuron collects incoming signals, decides if the total input message is strong enough, and permits its passage to another neuron.16Synapses, the connection points between two neurons, control the distribution of this communication by determining the direction of the signals transmitted.17Triggering or inhibiting signals arrive from various regions of the nervous system, sometimes opening synapses and other times, closing them. In this way, synapses halt weak signals and permit strong ones to pass.
At the same time, they also provide a selective function by choosing and magnifying some of the weaker signals and passing them on—not in one single direction but in many. The way that neurons collect signals and decide to transmit them might lead you to assume they have something resembling conscious human intellect. However, this is accomplished merely by very specially arranged groups of molecules, with no ability to think, nor any organs that permit them to perceive. The ability of a group of molecules flawlessly discharging such vitally important responsibilities is a sign of Allah’s supervision and eternal dominion over living things.
It is Allah, Lord of the Worlds, Who causes these impeccable processes to be carried out:
I have put my trust in Allah, my Lord and your Lord. There is no creature He does not hold by the forelock. My Lord is on a Straight Path. (Surah Hud: 56)
Synapses and Constant Electrical Current
Synapses, or the gaps between two nerve cells, are so small that they become visible only when magnified thousands of times. Yet this gap between two cells is also wide enough to prevent any electrical impulse’s leaping from one cell to another. Despite the billions of neurons in the nervous system, they never touch each other in any way. Therefore, from the point of view of the body’s electrical system, every synapse is an obstacle that must be overcome. Yet although they are separated from one another, no lapse is ever experienced in the body’s nerve network, because the signals transmitted electrically along the neurons continue across these spaces between them in chemical form.
Assume that an electrical signal—traveling at 354 kilometers (220 miles) per hour—reaches the end of the axon.18 Where will this stimulus go? How will it get past the synapse to continue on its way? This situation is analogous to coming to a river as you drive along in a car. At this point one has to change vehicles. In the same way that you get out of the car to cross the river in a boat, the electrical signal continues on its journey in another form, that is, in chemical form. Thanks to this chemical communication in the synapses, electrical signals can continue their journeys without interruption.
When a signal reaches the axon terminal, it gives rise to a so-called “message packet” that jumps the small synapse between two neurons and carries chemicals to set the receptor nerves in the neighboring neuron dendrites into action. These messenger molecules, known as neurotransmitters, cross the gap and set the second neuron into action in less than a millisecond.19Neurotransmitters are produced in the body of the nerve cell, are carried along the axon and stored in synaptic vesicles in the axon terminals. Each vesicle contains some 5,000 transmitter molecules,20which chemicals function as trigger or preventive signals. They either impel neurons to produce an electrical impulse, or else prevent them from firing.21
Recent research has shown that neurons can contain and release some 100 different types of neurotransmitters. 22 In other words, each neuron is like a chemical factory producing messengers to be employed in communications. Some neurotransmitters are employed in the triggering of electrical signals, others in the halting of electrical signals, and still others in acceleration or deceleration, in frequency-changing and energy storage. Each neuron releases only one or at most, a few different varieties of these neurotransmitters. When a neurotransmitter emerges, it crosses the synapse and the protein receptor on the receptive neuron’s cell membrane sets a protein into motion. At this point, synapses can be compared to a highway by which these chemical messengers are transmitted between nerve cells. The distance between them is approximately 0.00003 of a millimeter (118.10-8 of an inch). 23 Although this distance is very small, it is still a gap that the electrical signals must cross.
The amount of neurotransmitter released is much greater than what’s needed for attachment to the target dendrite. However, as in every other detail in the human body, this excess is an example of very wise creation. The extra neurotransmitters remaining in the synapse block the nerve to prevent the sending of excess signals. If these surplus molecules did not block the nerve, then the time needed for the signal to come to a stop would lengthen into seconds, even minutes. However, the signal transmission takes place in just a fraction of a second. The excess neurotransmitters are absorbed by the axon terminal, and the remainder decomposed by enzymes.24Just as in a relay race, electrical information is transmitted from cell to cell by means of neurotransmitters that serve as bridges. In this way, the flow of information continues uninterrupted, despite the gaps between the cell extensions.
Yet how do these two independent systems know that they must act together to perform this vital function? In addition, how is that there is no omission or delay in the information transmitted, and for data to be transmitted perfectly to its appropriate destination?
Each of these systems is no doubt a reflection of the knowledge and artistry of Allah. It flies in the face of logic and reason to expect these miraculous systems to have come into being spontaneously, or to maintain that unconscious cells engage in purposeful activities as the work of chance.
Cells That Produce Their Own Energy
As you have already seen, your body functions with electricity. However, in contrast to the other electrical systems we are accustomed to seeing, your body takes in no electricity from the outside.
Consider any electrical device. In order for it to function, it requires an electrical current provided from some outside source, or else to be by means of batteries. Otherwise, in the absence of electrical energy, even the most advanced machine will serve no purpose. But in contrast your body creates the very energy it needs. Trillions of cells produce—and use—electricity in order for life to continue.
Every cell is like a miniaturized battery that permits the body to function as a whole. Surrounding the cell is a liquid rich in potassium, and the inside is full of liquid high in sodium. When you mix potassium and sodium, the two chemicals react and an electricity emerges as a side product. This is analogous to a car battery's producing electricity when sulfuric acid and lead come in contact. In much the same way that radios, cassette players, flashlights, clocks and appliances work with energy they obtain from batteries, no car can operate without the energy stored in its battery. And both household and car batteries use chemical energy to produce electrical currents of various strengths.
Electricity used by the body is termed bioelectricity, the cellular exchange of negatively and positively charged particles known as ions. For example, when potassium is released outside the cell membrane and is replaced by sodium, a small electrical current develops; the potassium is sent inside the cell and sodium outside. According to a statement by Lendon H. Smith, M.D., a pediatrician and one of the best-known experts on health and nutrition; "In this way the cells act as tiny batteries with their own electromagnetic current." 25
The Cell Membrane’s Special Design for Electricity Production
It is electrical current that makes the lights in your home shine so brightly—a current that consists of the movement of electrons. The electricity in your cells, on the other hand, is carried by ions—electrically charged atoms or molecules. During the movement of ions, cells produce electricity from potential energy that is ready to be used. Similarly, the water in a dam produces electricity by passing through a hydroelectric station.
In cells, electricity is produced in this way: In all cells, there is a voltage difference in electrical charge along the cell membrane. This voltage difference causes the formation of what's referred to as electrical potential. This electrical potential in the cell membrane is known as resting potential, whose level is approximately 50 millivolts.
All cells use this potential energy to carry out activities inside themselves. But nerve and muscle cells also use this same energy for physiological tasks. Thanks to this current, contraction takes place in muscle cells, and this same current permits signals to be transmitted by nerve cells.
In the cell membrane, there are channels that permit only certain ions to pass through. By means of these channels, ions are sent inside or outside the cell. With the movement of positively or negatively charged particles, an electrical imbalance arises between the inside and the outside of the cell. This difference between the intra- and extra cellular fluids produces a flow of ions until equilibrium is re-established. The cell membrane, which separates the protoplasm inside the cell from the outside environment, has a semi-permeable structure that permits certain ions to pass through, while obstructing others. Therefore, when the cell feels the need for electricity, it opens one of these channels in order to complete the electrical circuit.
The channels in the cell membrane function like security personnel, allowing certain ions to pass and blocking the passage of others, which are actions requiring purposeful intelligence. There is no random passage here, but on the contrary, a mechanism of conscious selection. No doubt that it is impossible for insentient collections of molecules to undertake such responsibilities of their own accord. All this points to a fact that evolutionists deny: intelligent Creation.
There is a perfect equilibrium established by the positively electrically charged atoms—in other words ions—, inside the neuron, or nerve cell. The ions that assume important responsibilities in neurons are potassium and sodium, each with one positive charge, calcium with two positive charges, and chloride ions with one negative charge. At rest, the neuron is negatively charged, with negatively charged proteins and various ions present inside the nerve cell. There are more potassium ions inside the neuron than there are outside it, and fewer chloride and sodium ions. The equilibrium of the ions inside the cell has been arranged in such a way as to serve the specific purpose of transmitting electrical current and signals.
The message that arrives as an electrical signal, and is deposited at the receptors in the membrane of the receiving cell, initiates a series of processes inside the cell that is highly reminiscent of a row of dominoes. These processes, take place one after the other in a flawless order, leading to the opening of specific channels in the cell membrane. Thus the sodium ions taken into the cell, with its initial negative charge (of -70 millivolts), lead it to assume a neutral charge. The transfer of ions between the exterior and interior of the cell then produces a new electrical signal. The nerve cell that forwards the message—and has thus discharged its duty—returns to the resting position. This passage takes place with the opening and closing of the sodium and potassium channels in less than 1/1,000th of a second.
These processes, which have been simplified as much as possible for the sake of explanation here, actually contain exceedingly complex stages. If the production of electricity in a single cell were left for you to perform consciously, you would have to supervise the opening and closing of the channels and ensure ion equilibrium, all in less than 1/1,000 of a second. But of course it would be impossible for you to establish such equilibrium, nor to control and direct such a rapidly functioning system in billions of nerve cells. Yet this system continues even when you are asleep!
What is the level of electricity in the body? The difference between the charges inside and outside the cell is approximately 50 millivolts. According to the calculations by Professor Steven M. Simasko of Washington State University, if all the energy produced by the body's trillions of cells were added together, it would be enough to light a 40-watt light bulb.26
Some cells produce more electricity than others, an amount that varies depending on the task the cell performs and for what purpose the current electricity is used. For example, nerve cells must produce large quantities of electricity, because they transmit their messages over long distances. In a truly extraordinary way, cells are apparently aware of the importance of the tasks they perform, and how much energy they will require. They calculate this to perfection and discharge this responsibility with no interruptions over the course of a whole lifetime—another proof that electricity production takes place in a conscious manner.
This is one of the conditions that endow us with life. For example, if your heart cells produced less electricity than they actually do, they would be unable to carry out the pumping process properly (details of which we shall be examining in due course). The blood would be unable to carry oxygen and nutrients to all your cells, and a mortal danger would result. But as you have seen, along with the flawless creation in our bodies, every detail in their functioning is also evidence of exceptional wisdom.
Nothing in the structure of the cells is either superfluous or lacking. Everything is exactly as it should be. Although each of the 100 trillion cells in the human body is highly specialized in order to perform a variety of different functions, as a whole they possess flawless organization and functioning. At the same time, they have effective communication and interrelationships with other cells in the body, communicating with one another by means of electrical messages, receiving and transmitting the necessary information, and accomplishing to perfection whatever needs to be done.
If a cell anywhere in the body loses its electrical potential, its vital link to the nervous system will be broken. In the event that the cells in the visual center in the brain lose their electrical properties or that there are no voltage gates in the cell membranes, then it will be impossible for the signals transmitted by the retina to be received, and the individual will no longer be able to see. In every detail in the human body, there is much wisdom that is only newly being discovered.
When planning a building, architects also bear lots of details in mind and if they overlook even one of them, the project will be damaged. Indeed, from time to time, supports being slightly thinner than they should be, or the use of less cement in construction, may lead to the collapse of a structure dozens of floors high. Therefore, the quality of the materials used, their strength, and every stage of the project are all of great importance. The fact that the building you are in right now is secure and upright is the result of the labor, knowledge, calculations, planning and foresight of dozens of people who are endowed with reason and consciousness by our Lord. Nobody can maintain that this building in which you find yourself came into being gradually, as the result of chance. The organization inside the cell also possesses an even more sophisticated architecture that requires all the molecules in it to be used at exactly the right quantities and in exactly the right locations, by means of extraordinarily fine calculations. The cell is an organic structure consisting of many complex substances composed of as nitrogen, carbon and water, and one which will die and be eliminated unless it establishes vital links with the other systems in the body.
What we have described so far is merely a simplified account of the communication systems in neurons, which continue working throughout a person's life. It is difficult even for a person possessed of reason and intelligence to understand this intricacy, yet cells and hormones carry out these processes in billions of people with thorough competence and perfection.
But how did the exceedingly complex systems in each of the billions of nerve cells you possess actually come into being? How did the amazing harmony among them come about? How was such perfect communication established without the slightest confusion arising? How can this system, dependent upon extraordinarily sensitive balances and timing, continue working without the slightest error?
It's quite natural that so many questions beginning with the word "How" should come to mind. What is peculiar here is the stance of certain scientists who vainly seek to defend the theory of evolution, which maintains—in the face of all this contrary evidence—that these flawless systems actually came into being as the result of blind coincidences. Evolutionists seek to trace the origin of life to a fictitious "first cell" that came into being by chance or coincidence (a scenario to which even the word impossible would fail to do justice), but they have no answer to give to the above questions.
There is no doubt there exists a single explanation for the existence of such perfect mechanisms: it is Allah, Lord of the worlds, Who created cells from nothing. Our Lord, the Creator of us all, regulates the activities within the cell and the communications systems among them, right down to the finest detail.
He is Allah—the Creator, the Maker, the Giver of Form. To Him belong the Most Beautiful Names. Everything in the heavens and Earth glorifies Him. He is the Almighty, the All-Wise.(Surat al-Hashr: 24)
The Domino Sequence of Processes Within The Nerve Cells
How does information to the effect that your shoes are hurting your feet reach the brain? How can you perceive discomfort in your feet at the same intensity in your brain, despite the distance of several feet between them? Under normal conditions this signal should decrease in proportion to the distance involved. However, there is a special system in your body to overcome this.
The signals that set out from the pain-sensitive cells are carried along thanks to the ion movements taking place along the nerve cells. In this way, the signal travels with no loss of energy, and each transfer acquires new energy in each new region of the cell membrane.
The way the nerve signal is transmitted along the axon can be compared to the chain reaction that takes place when dominoes are lined up next to one another. When you push over the first domino, all the others —if set out at specific distances— will fall over in turn. When the first one falls over, a chain reaction ensues: consecutive tiles topple over until none remain standing. A similar chain reaction can be seen in the transmission of signals among neurons:
• The first domino will not fall until pushed with enough force. In a similar way, a nerve signal will not be triggered until stimulated with sufficient force—expressed as a threshold. The threshold phenomenon is observed in the transmission of signals pertaining to the senses. For example, we cannot hear very faint sounds because the signals they generate are not sufficiently powerful to set into motion signals from the auditory nerves.
• The chain of dominoes loses none of its energy as the individual dominoes fall over. The energy thus continues transmitted, undiminished, until the last one falls. That is because each standing domino falls over with the same kinetic energy (the energy a body possesses because of its speed). Neither do nerve signals lose any of their energy as their signal is transmitted.
• A domino falls in only one direction. In the same way, nerve stimuli move only from dendrite to axon.
As you see, every detail of the body is an example of very wise creation. The existence of all these must lead us to reflect more deeply, love our Lord more deeply, and give greater thanks to Him, the Creator of all.
One of the exemplary pieces of behavior of believers is revealed in the Qur'an:
Those who remember Allah, standing, sitting and lying on their sides, and reflect on the creation of the heavens and the Earth: "Our Lord, You have not created this for nothing. Glory be to You! So safeguard us from the punishment of the Fire."(Surah Al 'Imran: 191)
The Myelin Sheath: A Special Insulating Material
Nerve fibers that transmit messages from the brain to the muscles and other organs and back to the brain are covered with a special fatty tissue, known as myelin. This not only protects the nerve fibers, but also assists them in forwarding electrical signals.
Myelin functions like the non-conductive plastic or rubber coatings around electrical cables, insulating them so that no one touching them will experience a shock and also so that no electric current leaks out, leading to a loss of power. Were it not for the myelin, electrical signals would leak into surrounding tissues and thus dilute the signal, and possibly harm the body. In addition, this insulating substance significantly increases conductivity, allowing signals to move more quickly.
Small unmyelinated fibers conduct at speeds of only 1 to 2 meters (3.3 to 6.5 feet) per second, while those covered in myelin can do so at speeds of up to 100 meters (328 feet) per second.27
The myelin-covered nerve fibers transmit signals from our sense organs to the brain and from the brain and spinal column to voluntary muscles. Actions under our control are so rapid, often so automatic, that it seems as if the muscles contract as soon as the thought occurs to us. The reason our movements follow our perceptions so quickly, without our expending a conscious effort, is that nerve transmission takes place at speeds of up to 354 kilometers (220 miles) an hour.28 In the 1-meter-long (3.3-foot) sciatic nerve in the legs, that speed rises to 467 kilometers (290 miles) per hour. 29
In some situation, the timing of signals reaches extraordinary precision. For us to make a distinction between B and P sounds when we speak, our lips need to open in as briefly as 1/30,000 second before our vocal cords move. Therefore, our listeners do not confuse the letter P with the letter B, which emerges as a result of the simultaneous opening of our lips and vibration of our vocal cords. In other words, we owe our ability to distinguish between the words pat and bat to a timeframe of just thirty thousandths of a second.30 This distinction is of great importance to our communication. But since the brain arranges this time frame for itself, there is no need for you to think about it. When the signal for the vocalization of P or B occurs, all these events take place in sequence, one after the other.
To better understand the significance of the myelin sheath, consider Multiple Sclerosis (MS). In this disease, the protective sheath around the nerves that carry messages in the brain and spinal column is damaged in places, and there appears hardened tissue known as sclerosis. These hardened tissues may occur in many sites throughout the nervous system and—by preventing the transmission of signals along the nerves and interfering with communication between the brain and other organs— lead to a wide variety of defects. In the same way that holes may damage the insulation around electrical cables, gaps can also appear in the defective myelin sheath, which interferes with the transmission of messages.
When you remove one of the standing dominoes in the line, the consecutive falling of the line is interrupted when the sequence reaches this gap. In the same way, a damaged myelin sheath causes an interruption in the transmission of nerve signals. The effect of one missing domino can be compared to that of serious neural or spinal damage. Nerve signals cannot be transmitted along until the damage gets repaired.
Among the symptoms of MS are fatigue, pins-and-needles sensations, numbness, a lack of or reduction in feeling, balance problems, speech impairments, trembling, stiffness hardening of muscles in the arms and legs, weakness, vision defects, oversensitivity to heat, short-term memory problems, and difficulties in judgment and decision-making. These symptoms can vary depending on the region in which nerves have been damaged. Since the brain controls thinking and movement, damage in this region may affect any number of functions—memory, understanding, character, touch, hearing, sight and muscle power.
When damage takes place in the cerebellum, at the rear of the brain, it causes loss of balance during walking and running by affecting coordination. It may lead to weakness in the nerves concerned with vision, speech, swallowing and hearing. Damage in the brain stem can cause functional defects regarding eye movements, respiration, heartbeat, sweating and the excretory system. When the damage is to the spinal column, loss of communication occurs between the body and brain. Moreover, the brain's signals concerning the legs, hands and other organs are prevented from reaching their destinations. In progressive cases, the disease can lead to partial or total paralysis—an important example of the importance of the myelin sheath.
The Wisdom of Creation of The Nodes of Ranvier
In human beings, nerve signals can generally travel at 100 meters (328 feet) a second.31 How is such a speed achieved? The secret lies in the way the myelin sheath is installed, being interrupted at points known as the Nodes of Ranvier. There is approximately one node, a few microns (1/1000 millimeter = 0.0000039 of an inch) wide, every millimeter (0.039inch) on this sheath.
The sodium and potassium channels regulating the passage of ions on the cell membrane are also collected on these nodes. Nerve signals following sodium ions head directly for these nodes. Thanks to this, the transmission of a signal from your central nervous system or spinal column to your toes takes place in as little as one hundredth of a second.32 Gerald L. Schroeder received his doctorate in the fields of molecular biology and quantum physics from the Massachusetts Institute of Technology, and has written scientific articles for such journals as Time, Newsweek and Scientific American. He is one of those scientists who lose no opportunity of expressing their amazement at our bodies' extraordinariness:
... most of us life’s mechanisms work in proper order is a wondrous miracle. When they do not is a tragedy. The system described and diagrammed above [the nodes of Ranvier] is an ingenious one for communicating massive amounts of complex information. The parallel processing and perfect timing involved are as elegant as the finest supercomputer. Perhaps someday, in the age of communications technology now upon us, we will imitate and exploit our own design: In the meantime we can only wonder at the workings of our chemistry. 33
In order for the nerve cells to transmit signals each nerve membrane must be set in motion in turn. The time this requires seriously reduces the speed of the signals along the nerves. However, in the face of this deceleration, a precaution has been taken in our bodies. The presence of the myelin sheath—and its interruption at the points known as the nodes of Ranvier—cause this transmission to be extremely rapid.
Speed in Signal Transmission
The cell's charging and discharging itself, the secretion of chemical substances, their being broken down and then reconstituted—all takes place several hundred times a second. Though these activities can be summarized in one sentence, each is an exceedingly complex process, which takes place at amazing speed. The information needed to plan and produce these is encoded in our DNA, which carries our genetic data.
As you have already seen, electrical stimuli can travel in the brain in a matter of milliseconds. But some signals take an express route. In bright light, for example, the shrinking of the pupil of the eye takes place in a matter of moments: Yet the command for the pupil to contract must cross four or five synapses between brainstem neurons controlling the iris.
One factor affecting how signal production takes place so quickly is the radius of the axons. As the radius increases, signal production accelerate. For example, some animals such as the squid have axons as large as 1 millimeter (0.039 inch) in diameter. Thanks to this, nerve impulses are transmitted faster, and attain a speed of up to 25 meters (82 feet) per second.34 If this feature observed in squid were true of human cells, then the diameter of our arms would be measured in meters.35 That is because a large number of nerves traverse the same region in the human body, and axons of this size would turn into a prohibitive factor in such regions. In the human body, a much more effective method accelerates signal production: insulation. When you need to pull your hand back from a hot surface, the nerves that permit the relevant muscles to act transmit signals very fast because they are insulated with a layer of fatty molecules layer known as myelin, as already mentioned.
The way electrical signals in human beings are accelerated by an insulating material, in contrast to other living things, is one of the signs of intelligent creation. The human body's electrical system provides rapid transmission, does not hinder our ability to move, nor impairs our aesthetic appearance. These attributes being all present at same time can not be accounted for in terms of chance. Clearly on display here are the Superior Intellect and Knowledge of our Almighty Lord, the Creator of all things.
In the Qur'an Allah reveals this concerning the creation of Man:
We created man in the finest mould.(Surat at-Tin: 4)
9.Tortora, G.J., Anagnostakos, N.P., Principles of Anatomy and Physiology, Harper & Row, New York, 1981, s. 29; [Craig Savige, "Electrical design in the human body"; http://www.answersingenesis.org/creation/v22/i1/electrical.asp]