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.

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.

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.

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.62 It 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.63 The 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 exploring this site, visiting 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.64 This 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.66 This 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.

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

Professor Eric Kandel

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.

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.69 In 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.

The picture shows communication between two neurons. The most important elements in this communication are messenger molecules known as "neurotransmitters."

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.

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.

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.

62 Eric H. Chudler, "The Hows, Whats and Whos of Neuroscience," 2001, http://faculty.washington.edu/ chudler/what.html
63 M.J. Farabee, "Online Biology Book: The Nervous System," 2000, http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookNERV.html
64 J.P. Changeux, P. Ricoeur, "What Makes Us Think?," Princeton University Press, 2000, p. 78
65 G. Fischbach, "Dialogues on the Brain: Overview," The Harvard Mahoney Neuroscience Institute Letter, 1993, vol. 2
66 M. Chicurel, C.D. Franco, "The Inner Life of Neurons," The Harvard Mahoney Neuroscience Institute Letter, 1995, vol. 4, no. 2
67 The Nobel Foundation, "Press Release," 9 October 2000, http://www.nobel.se/medicine/laureates/2000/illpres/kandel.html
68 E. Kandel, J.H. Schwartz, T.M. Jessell, Principles of Neural Science, McGraw Hill Publishing, 2000, p. 277.
69 Eric H. Chudler, "Making Connections-The Synapse," 2001, http://faculty.washington.edu/chudler/synapse.html
70 Principles of Neural Science, p. 176
71 Axel Brunger, "Neurotransmission Machinery Visualized for the First Time," 1998, http://www.hhmi.org/news/ brunger.html