Communication In Nerve Cells
Imagine that you are walking bare-foot in your kitchen and you walk on a piece of glass. The amount of time from when you walk on the glass until you feel the pain in your brain is only a few thousandths of a second. This time is so short that you cannot notice it, but during this time, a message was transmitted from your toe to your brain. This rapid and perfect communication was managed by nerve cells or, as they are called in biology, neurons.
Just look around: everything we see is designed according to a special purpose. For example, a telephone with its plastic and electronic parts, buttons, line and other components, has been designed to establish communication with other people. In the same way, the reason for the creation of neurons is evident on first inspection. (Of course, this requires an inspection done under an advanced microscope.) The first thing you notice, along with the other organelles in the cells, is the special extensions on the neurons which resemble arms projecting from a body; these are called axons and dendrites. It is possible to compare a neuron with a high technology telephone central. The size of this cellular telephone central is only between 0.004 and 0.1 of a millimeter, but its communication mechanism is unparalleled in the world today. The axon and dendrites mentioned above provide the communications lines that enable communication with other sites.
Because of the nerve cells that surround the body like a net, messages from the brain reach the most remote areas of the body with great speed. This speed is due to the flawless design of the nervous system.
The diameter of a neuron is on ten microns on average. (A micron is equal to one thousandth of a millimeter) If we could arrange the 100 billion neurons in the human brain side by side in a line, the line (ten microns in diameter and too small to be seen by the naked eye) would stretch a thousand kilometers. The existence of such an extensive communication network in a brain weighing only 1400 grams is astonishing.
Consider these figures a little more closely. Neurons are so small that fifty average sized ones could fit on the period at the end of this sentence.62It is for this reason that a great amount of what we know about neurons has been obtained indirectly.
When we examine the communication extensions on nerve cells, we see that on every neuron there are many dendrites that transmit communication from other neurons to the body of the cell. Most frequently, the function of the single axon is to transmit the message received from the body of the cell through the terminals and extensions.
At this point, we must point out the special design of axons. A special covering layer called "myelin sheath" encloses an axon. Nerve impulses are propagated at specific points along the myelin sheath;these points are called "the nodes of Ranvier." Research has shown that signals jumping from node to node travel hundreds of times faster than signals traveling along the surface of the axon.63The sheath and "nodes" on the axon make it possible for the signal to be transmitted in the most suitable and rapid manner.
Neurons establish communication in our bodies by a unique method that comprises extraordinarily complex electrical and chemical operations, ensuring flawless coordination both in the brain and between the brain and other organs. When you complete a simple action, such as holding this book in your hands, flipping its pages or running your eye through its sentences, there is a very dense communication traffic in the nerve cells deep within your body. Examining closely the neurons that establish this extraordinary communication network will help us to understand better what an important wonder of creation they are.
Design in the Synapses
Hundreds of millions of telephone calls can be made every moment throughout the world. Despite this, in the brain of one individual one quadrillion (1,000,000,000,000,000) communications can occur simultaneously.
The communication between two neurons happens between connective points called "synapses" located on the ends of the axon terminals. Just as a telephone central allows many people to communicate with one another at the same time, in a similar way, a neuron can communicate with several neurons currently through the synapses. Hundreds of millions of telephone conversations can be made in the world at the same time. Compared with this, it is estimated that there are one quadrillion synapses in the human brain, all which add up to 1,000,000,000,000,000 communications.64This extraordinary communication is an important factor that has led scientists to refer to the brain as "the most complex structure in the known universe."65
We can also say this in another way: a typical nerve cell in the human brain, for example, harbors tens of thousands of synapses.66This means that one neuron can establish a connection at the same time with tens of thousands of different nerve cells. Imagine the difficulty you would have talking on two telephones at the same time; this feat by one nerve cell of tens of thousands of simultaneous connections is an example of a marvelous creation.
Profesör Eric Kandel
Until recently, the communication junctions among neurons were thought to be stable, but once again scientists have been surprised by the fact that the shape of synapses change according to the structure of the chemical messenger. Professor Eric Kandel received the Nobel Prize in 2000 for this discovery. This expert design can be summarized as follows: there exists a mechanism in the synapse that alters the form of the synapse according to the strength of the stimulus. When it receives a powerful stimulus, the synapse makes it possible for this stimulus to be transmitted to other cells, undiminished, and in the most productive way. Another important point to be emphasized is that this system was understood after experiments on sea slugs. Professor Kandel himself confessed that the nervous system in human beings and mammals is too complex for research to understand completely.67
Chemical Communication in Neurons
Most people think that the connection between neurons is established only by electric signals. This is not true, since chemical communication is an important part of this process. When we investigate the communication between two neurons, we understand better the wonderful elements in chemical communication.
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The picture shows communication between two neurons. The most important elements in this communication are messenger molecules known as "neurotransmitters."
The chemical communication involves of messenger molecules called "neurotransmitters." These are produced in the body of the nerve cell, carried along the axon, and stored in tiny vesicles on the axon terminals. In each vesicle there are about five thousand units of transmitter.68 Recent research has shown that neurons can contain and release more than one kind of chemical messengers.69In other words, every neuron is like a chemical plant that produces the messengers that will be used in communication.
The neuron that sends the signal is the "transmitter" and the one to which it is sent the "receiver." The transmitter and receiver neurons meet at the synapse, a space about 0.00003 of a millimeter.70
A particular electric signal activates the messengers on the axon terminal of the transmitting nerve cell. The synaptic endings filled with chemical messengers combine with the cell membrane and release the molecules inside them into the synapse cavity. The message carried by the messengers is sent to the receptors on the membrane of the receiving neuron. Different receptors establish a connection with different messenger molecules. The message carried by the chemical messenger molecules is thus perceived by the receiver neuron.
Adding another part to a computer requires complex engineering calculations if the whole computer is not to be ruined. Certainly, a fusion system that will be compatible with a cell membrane, which is much more complex than a computer, cannot be a chance occurrence. God creates this fusion.
We have described this system only in rough outline, and every stage of it is filled with operations that have not been completely resolved by scientists. In fact, scientists have had only a murky picture of some of the events relative to this communication.71
Consider the fusion of the synaptic ending with the cell membrane. The operation described by the word "fusion" is a very special union similar to the connection of a modular unit to a highly advanced computer. The connection of a part to a computer depends on complicated engineering calculations. Otherwise, the part will not fit the computer, and the computer may even be ruined. A cell is much more complex than a computer, and a harmonious union of a neurotransmitter with a cell membrane is not a random occurrence. All these complex operations that happen at every moment are under the control of God Who created them.
If we receive an injury in a part of our body, the brain is notified of this pain through a message.. In response to this message, a special neuron located in the brain and the spinal column reduces the pain by secreting endorphins.
The Planning and Timing in the Messenger Molecules
The density of the chemical messengers and the time they remain in the synapse cavity directly influence the communication between the two neurons. Different mechanisms exist for each chemical messenger. Some messengers disperse after they deliver their messages. Others are broken down by special enzymes after they have performed their functions. For example, the messenger molecule called "acetylcholine" is converted by a special enzyme into choline and acetate.
There is yet another marvelous mechanism in the nerve cells: The messengers that transmit a message to the receptor cell are gathered back again into the transmitter cell and are stored there to be used in a subsequent message. This operation is performed by a few special molecules. The activity of the dopamine and serotonin molecules is regulated in this way. If we consider how difficult it is to recycle products, we can better understand the effectiveness of this mechanism in the nerve cells.
Every phase of chemical communication occurs within an incredibly delicate balance. Every messenger molecule used in every communication, and every protein and enzyme that performs a function in the various stages, must be designed. The number of messenger molecules that will be stored, how long the receiver cell will be stimulated, the time for disintegration or reassembly are a part of the necessary communication balances. Moreover, an important number of details relating to communication balances is still unknown.
Parkinson's disease is a condition that destroys muscle coordination, makes movement difficult, and causes tremors. The cause of this disease is the destruction of the balance between the messenger molecules dopamine and acetylcholine. When some nerve cells in the brain produce less dopamine than is required, the result is the loss of muscle control. This fact came to light only recently (Professor Arvid Carlsson was awarded by the Nobel Prize for his discovery).
These delicate balances and complex mechanisms are not composed of a random series of events. The One Who creates them, keeps them under His power, gives them to the service of human beings and takes them back again when He wishes, is God, to Whom belongs eternal power and knowledge.
The Electrical Communication Between Neurons
In the picture on the left you see a patient with Parkinson's disease working with her doctor. In their attempt to find a cure for Parkinson's, scientists continue to do research on this disease.
At every moment, every nerve cell experiences a complex conversion. Communication via neurons is an operation that occurs when electro-chemical or chemical messengers generate an electrical signal.
In order to understand electrical communication, we must first consider another balance mechanism: the marvelous balance formed by the electric charge in nerve cells, the ions. Ions perform an important function within neurons; there is one positively charged sodium and potassium ion, two positively charged calcium ions and one negatively charged chloride ion. In addition, there are some negatively charged protein molecules.
In its resting state, a neuron is negatively charged. In this state, negatively charged proteins and various ions are within the nerve cell. Compared to the number outside, there are more potassium ions and less chloride and sodium ions inside the neuron.72 These are not arranged at random, and this proportion is specially determined and maintained.
A message left on a receptor on the membrane of a nerve cell starts a series of reactions inside the cell similar to a row of falling dominoes.
The message left on the membrane receptors in the nerve cell initiates a serial operation in the cell that is reminiscent of the domino effect. In the course of this operation whose details are not yet fully known, it is thought that hundreds of proteins perform a function. This operation happens serially and in perfect order, causing particular ion channels to open on the cell's membrane. The result is that the sodium ions that are taken inside the cell neutralize the cell that earlier had a negative electric charge (-70 millivolts). The transfer of ions between the inside and the outside of the cell creates an electric signal. The operations that we have described here in the simplest of terms begin and end in less than one thousandth of a second.
The signal that is created travels quickly along the axon and initiates the chemical operations that will pass the message to other cells on the synapse points on the ends of the terminals. The average speed of the signal along the axon is 120 meters per second.73 A simple calculation will show us that this speed equals 432 kilometers per hour.
The nerve cell that transmitted the message completes its task and returns to its resting state. This restoration happens by the opening and closing of the sodium and potassium channels within a period of less than one thousandth of a second. Without a clock produced by means of high technology, you cannot measure one thousandth of a second. Imagine that you had such a watch; you still could not coordinate the opening and closing of the ion channels on one single nerve cell. If you attempted to initiate the millions of operations that occur every moment, a mistake in the timing of just one thousandth of a second would derail the operations.
Ions have an important function in a neuron. There is one positive sodium ion, one positive potassium ion, two positive calcium ions, and one negative chloride ion. The proportion of potassium inside the neuron is larger compared to that on the outside while the proportion of chloride and sodium is lower. What we have to notice here is that this arrangement must be specially designed and maintained in order to keep these balances in a definite proportion; it cannot happen by chance
An Evident Fact
Neurons establish thousands of connections among themselves
There is another feature that distinguishes neurons from the rest of our cells. Other cells in our bodies are constantly being renewed but neurons do not change. With age, their number decreases but the nerve cells present in a person's old age are the same ones he had in his youth. What has been described to this point has been a really simplified account of communication systems in the neurons that function throughout a person's life. Even someone with intelligence and knowledge would have difficulty understanding these things; cells and hormones have performed these functions very successfully without error in the millions of individuals that have lived in the world since the beginning.
How did these highly complex systems in each one of our nerve cells come into being? How did the incredible harmony among the hundreds of millions of cells in our bodies come into existence? How is such marvelous communication system ensured without confusion arising? How does this system, which depends on remarkably delicate balance and timing, work without making an error?
It is natural that hundreds of questions about "how" fill the human mind. Despite all these facts, some scientists vainly try to defend the evolutionist claim that these flawless systems came to be totally as a result of blind chance. Impossible is not too strong a word to describe the attempts of evolutionists who try to connect the origins of life to an imaginary "primeval cell" formed by chance; they have no answers to the questions posed above.
One point in articles written by evolutionists attracts our attention; there is no scientific explanation of how evolution happens. Instead, they propose that the molecules and proteins that function in communication appear at some stage in so-called evolution, and that they have come down to us with no change in their structure. Certainly, a claim such as this, which has not even the slightest proof, is an immense deceit. In the guise of science, they play a game of words designed to deny creation.
All praise belongs to God, the Lord of the heavens and the Lord of the Earth, Lord of all the worlds. All greatness belongs to Him in the heavens and Earth; He is the Almighty, the All-Wise. (Qur'an, 45: 36-37)
There is no doubt that there is only one explanation why such a marvelous mechanism has come into existence: God, the Lord of all worlds, creates cells from nothing. It is our Lord, the Creator of us all, Who designs the incredibly complex and interconnected communication systems in cells down to their finest details. It is God Who gave never resting atoms, proteins and molecules to our service; and it is only He Who is worthy to be praised and exalted.