The Muscular System That Operates on Electrical Energy
You expend energy in reading these lines, in turning the pages of this book and even just sitting back in your chair. Your skeletal muscles provide this strength and use it wherever necessary. Various muscles extend to every point in your body and represent some 45% of the human body’s weight.
Every muscle consists of large numbers of fibers between 0.5 and 14 centimeters (0.2 and 5.5 of an inch) in length and an average 0.1 millimeter (0.0039 of an inch) in diameter. Muscle tissue’s most important feature is its ability to contract, and its ability to do work increases in direct relation to its ability to contract. Thanks to this ability, you are able to drink water, walk, speak, close your eyes and turn your head.
Muscles in the human body are divided into two groups, those under conscious control (voluntary muscles) and involuntary ones. In order to activate voluntary muscles, one needs to think and decide. When you want to climb stairs, for instance, your muscles contract at the command from your brain and perform the action of lifting your legs. On the other hand, the working of involuntary muscles does not depend upon volition. Since the functions of these involuntary muscles are extremely vital ones, their contraction and expansion is controlled, by the mercy of Allah, by the so-called autonomous nervous system. Therefore, your heart, stomach and intestines perform their duties regardless of your conscious will. This is a most vital precaution, for if functions like heartbeat and digestion had been entrusted to conscious control, it would of course be impossible for humans to fulfill them constantly. That would spell the end of human life.
The flat muscles that work involuntarily move slowly, but their contractions are long-lasting. They do not tire, and thus they can maintain systems of vital importance to the body for lengthy periods of time. Blood vessels, the digestive tract and the walls of the excretory canals, for instance, are all furnished with muscles of this kind. Since these flat muscles work independently of the skeletal muscles, they are responsible for only the movements of internal organs.
Imagine that the involuntary muscles were temporarily placed under your control. You would need to contract the walls of your stomach in order for digestion to take place, and contract your heart to pump blood. Even if you concentrated on only those tasks, you still couldn’t possibly manage them. That’s because these muscles continue working on your behalf when you are asleep, and perform their functions for a whole lifetime, never resting. If conscious, therefore, muscular contractions would stop when you wanted to sleep or rest, and that would spell the end of your life. As we have seen, the flawless order in our heartbeat is sufficient to show us the mercy that Allah has bestowed upon us.
Actions That Take Place with Electrical Current
When you want to move a finger, countless nerve cells in your brain start sending minute electrical signals to one another. These currents are later transmitted from the brain to the arm, by means of the medulla oblongata and spinal cord, through one of the many branches of the nervous system. When this minute electrical current issuing from the brain reaches the forearm, there, it causes muscle cells to contract, which in turn pulls a tendon that causes your finger to move.
All these phenomena take place at practically the same time. There is a flow of data from both the eyes and the finger back to the brain, thanks to which the brain checks whether the movement is in line with the command it gave. If the movement of the finger meets an obstacle and is unable to do what is required of it, the brain can modify the situation by issuing new commands.
Gerald L. Schroeder cites one example of the supervision between the muscles and the brain:
Muscle distribution within our bodies is filled with cleverness. Hold your hand up and bend your fingers. Notice that the muscles that allow you to cup your hand by bending your fingers down are not located in your fingers. Make a fist and feel the inner, smooth side of your arm just below the elbow. Feel those muscles flex. They are connected via tendons to your fingers and give the pull that shapes your fist.
By having the muscles located on the arm rather than at the fingers, the fingers remain slim enough to do fine work such as holding a stick or typing a page. But when you pull your fingers down, there is another joint in the line of action, the wrist. Why isn't that pulled down along with the fingers? Now feel the outer, hairy side of your arm just below the elbow. Feel the other muscles at work there. They get the command to apply just the correct force to hold the wrist steady when your brain says bend fingers only, and they allow the wrist to bend when the cranial message is: wrist also in action. But we never think of it because it's all controlled at the less-than-conscious level. 52
Thanks to tension receptors on the muscles, such actions as running, walking, opening a door or climbing stairs can be carried out in a smooth, coordinated manner. These receptors keep the nervous system constantly informed, giving the brain feedback about the status of the muscles, and the degree and speed of their contraction. Close monitoring and co-ordination of muscular activities is ensured, and as a result, you can walk along without stumbling, climb up and down stairs without falling, and lift your spoon to your mouth without your hand shaking. All these actions are made possible by the will of Allah, thanks to the flawless order of the functioning inside the body.
The Originator of the heavens and Earth. When He decides on something, He just says to it, "Be!" And it is. (Surat al-Baqara: 117)
How Do Muscles Contract?
For any contraction to begin, muscle fibers must be stimulated. The mechanical energy that emerges as a result contraction is provided from the muscle's resources chemical energy. Therefore, the work that the muscle must do depends on its chemical energy being translated into mechanical energy.
Muscles are like biological machines that turn chemical energy into mechanical power. However, the functioning of these machines— in other words, our ability to move—requires energy. Glucose in the blood provides the necessary energy, just like the fuel that makes an engine work.
The body obtains this energy needed for muscle movement from the food we eat. Digested carbohydrates, fats and proteins reach the muscles by way of the liver. Proteins that serve in the development and repair of tissues are reduced to the level of amino acids, while carbohydrates and fats provide necessary energy in the process of being broken down chemically. Energy released during this process is used by the proteins of muscles for the purpose of contraction. These chemical reactions require a high level of oxygen, which is not easy to obtain. In order to overcome this problem the muscles use their ability to turn glucose into lactic acid without the presence of oxygen; and the requisite energy emerges during this process.
Only limited quantities of the glucose and oxygen essential to contraction are present in the muscles. For that reason, additional quantities of both substances are carried to the muscular system by means of the bloodstream. The amount of blood reaching the working muscle is therefore important. The amount of blood a muscle requires during the performance of work may rise 10 to 20 times. This increased requirement raises the heartbeat and causes the blood vessels leading to the heart to expand.
The design of muscle cells is very special. These cells’ structure can release the energy inside the sugar molecule and use it during contraction. Both release of energy from the sugar molecule and the transformation of that energy into physical strength are carried out inside the muscle cell. Energy produced in the muscle cell affects the proteins constituting the muscle. As a result of this, the proteins attract one another and the cell contracts by shortening. When thousands of cells shorten simultaneously, the entire muscle tissue contracts. The muscles, attached to the bones by tendons, move the bones by means of this contraction.
The functioning of all the skeletal muscles we use in order to move takes place via this same mechanism. When to stretch out, you bend your elbow at the desired angle, when to eat you cause your jawbone to chew, and when you set your leg muscles in motion to run, behind these movements lie the electrical activity of the microscopic cells.
In order for a muscle to contract, the electrical signal from the motor neurons must pass between the membranes of the muscle cells and the nerve cell. As a result of the chemical reaction that takes place with this electrical impulse, the proteins actin and myosin in the muscle fiber slide over one another, thus shortening the length of that fiber. During this reaction, a degree of heat is emitted, and the total heat emitted by all the muscles determines our normal body temperature. For that reason, the muscles that shiver and tremble in very cold environments are trying to keep the body temperature stable by producing extra heat through involuntary motion.
The contractions carried out by a muscle fiber as a result of the electrical impulses from the nerve fiber reaching it one by one eventually fatigue this muscle fiber. It needs to rest. Other fibers that have not previously contracted then go into action and permit the contractions to continue. However, if the electrical impulses from the nerve continue at very frequent intervals, giving the muscle fibers no opportunity to rest, then a state of contraction takes place that prevents further movement.
When you want to open a door, an electrical signal leaves your brain and via the spinal column, heads directly towards your fingers. The electrical current passes over the muscle surface and triggers the millions of muscle fibers which, upon receiving the stimulus, immediately contract. Finally, the bicep or tricep muscle as a whole contract, and your arm bends at the elbow.
All these processes take place in the blink of an eye. Thus, the electrical current passing through the nerves proceeds in a millisecond, or 1/1000 seconds, and sets the muscle fibers in motion.
The commands reaching the muscles are both produced in and transported by the nervous system. In that way, the muscular system functions under the command of the nervous system, and the muscles work harmoniously thanks to this co-ordination in the body.
Muscle cells perform these deliberate actions in a matter of milliseconds, without your having to think about them. Since that obedience cannot belong to the cells themselves, who tells them what to produce, and when? Whose intelligence and consciousness guide the hormones and molecules to the correct location? Who tells them they are at the right place when they arrive, and who directs all these actions? The superior Intelligence manifested in the movement of the muscles belongs to Allah, the Creator of the cell and the molecules, Who inspires their behavior.
Implications of The Disease Known as Als
ALS (amyotrophic lateral sclerosis) is one of those diseases that dramatize the effect of the nervous system on the muscles. ALS, whose cause is unknown, is the disease that has paralyzed the famous British scientist Stephen Hawking. The motor neurons traveling from the brain to the spinal column and thence to the muscles become atrophied by this disease. When nerves that activate the muscles are damaged, the muscles become incapable of stimulation. As a consequence, the sufferers quickly lose their ability to move, then to speak.
This disease begins with a feeling of weakness in the arm and leg muscles, and increasingly affects speech, chewing and breathing, and can eventually prove fatal due to its effect on the chest muscles involved in respiration.
The etiology of ALS is as yet unknown. In their studies scientists have observed an excessive level of a neurotransmitter known as glutamate in the nerve connections, which prevents normal transmission of impulses.
Stephen Hawking currently uses an electric wheelchair to move and a speech device controlled by his jaw muscles to communicate. Despite having lost all control over his muscles, another one of those suffering from this disease has established communication with others by means of an alphabet signaled by his eye movements.
No doubt ALS by itself reveals the vital importance of our motor nervous system—which we never reflect upon until we encounter a disease of this kind. Normally working perfectly without our even thinking about it, the nervous system is one of the countless examples of Allah’s mercy on us. Our duty is to appreciate Him and give thanks for the blessings He has created:
Allah shows favor to humanity, but most of them are not thankful.(Surat an-Naml: 73)
The Electrical Order in The Muscle Cells
Transmission of electrical current to the muscle cells causes a voltage change. This change affects sacs in the sensitive calcium channels, and calcium ions are deposited inside the cell. Release of calcium from the sacs causes tropomyosins to move and the region where actin interact with myosin to open. Via this very important process, contraction in the muscle cells can occur as the proteins slide over one another. In their normal state, however, actin fibers are covered with proteins known as tropomyosins.53 Therefore, the release of calcium ions, via the electrical interaction inside the muscle cells, provides our ability to move.
When a nervous stimulus arrives at the muscle fibers, a chain reaction of complex biological phenomena begins within the cell, releasing the energy the muscle fibers need to contract. When the electrical current reaches a muscle cell and calcium atoms are released, this is transmitted to the DNA. In the relevant sections of the DNA, RNA synthesis takes place where the requisite enzymes* are to be manufactured. In order for this to occur, all the stages of enzyme synthesis, DNA activation, the initiation of RNA production and its transport outside the nucleus must be controlled by enzymes.54Finally, ATPaz*, just one of the enzymes produced, carries out the use of ATPs*, and another enzyme ensures that the ATPaz goes to the correct location. Following that, millions of the energy packets called ATP are combined with millions of proteins, and contraction occurs as the ATP is used up. In the wake of contraction, ATP is again expended. The calcium ions distributed through the cell are again brought back to fill the sacs. Tropomyosins cover the actins once again, thus preparing millions of muscle fibers for another contraction.
The substance ATP inside the cell turns into ADP* by giving off phosphorus and releasing a significant quantity of energy. However, since this source of energy rapidly becomes used up, the ADP that forms needs to be turned into ATP. When the ATP is formed, there is an attendant release of energy when carbohydrate and fats are oxidized and broken down. In the event that there is insufficient oxygen, then lactic acid form, as the leftover byproduct of oxidation. The accumulated lactic acid and ADP are referred to as "fatigue substances" that impair the ability of the muscle cell to keep on contracting. Performing rapid and heavy actions therefore leads to increased accumulation of fatigue substances in the muscle tissue, depending on the intensity of the work done.
The chemical reactions briefly outlined here actually consist of many complex processes that it would take pages to describe in full. All of these processes, to which only brief space can be devoted here, take place in our bodies without interfering with one another, at high speed and without interruption. Millions of cells play a part in forming the command that will travel from your brain to your finger muscle to make that finger contract. Bearing in mind that thousands of reactions take place in every cell, you can better grasp what a complex, wide-ranging infrastructure is needed for a seemingly elementary task like moving a finger. And during this action, other activities in the body continue without interruption: The heart beats, new blood cells are produced, the eyes transmit images of your surroundings to the brain, the kidneys filter your blood, the lungs exchange CO2-laden air for fresh, the digestive system transmits nutrients into the bloodstream that will provide energy; and countless more vital functions continue to be performed.
Allah, there is no god but Him, the Living, the Self-Sustaining. He is not subject to drowsiness or sleep. Everything in the heavens and the Earth belongs to Him. Who can intercede with Him except by His permission? He knows what is before them and what is behind them but they cannot grasp any of His knowledge save what He wills. His Footstool encompasses the heavens and the Earth, and their preservation does not tire Him. He is the Most High, the Magnificent. (Surat al-Baqara: 255)
Molecules Whose Importance is Emphasized with Parkinson's Disease
The intensity and length of time the chemical messenger remains at the synapse gap directly influences the communication between two neurons. There is a different mechanism for each chemical messenger. Some messengers are dispersed into their surroundings after handing on the message they bear. Others are broken down by special enzymes. For instance, a special enzyme turns the messenger molecule acetylcholine into choline and acetate.
There is yet another marvelous mechanism in nerve cells. Some of the messengers that transmit the message to the receptor cells are collected again by the providing cell and stored at the synapse for use in subsequent communications. This process is performed by a number of special molecules. For example, the activities of the molecules dopamine and serotonin are regulated in this way. If we consider the great efforts presently being made to recycle waste products, the efficiency of the nerve cells' recycling mechanism can be better understood.
Each stage of this chemical communication depends on the most delicate balances. The messenger molecules employed for every communication, and the proteins and enzymes that serve in the various phases of that communication, are all specifically determined. However, many details of these communications are still unknown.
Parkinson's disease impairs coordination between the muscles, makes movements difficult and causes trembling. The cause of this disease is an imbalance between the messenger molecules dopamine and acetylcholine. Some nerve cells in the brain produce less dopamine than is required, leading to a loss of muscle control. This is a fairly new discovery, and earned Professor Arvid Carlsson the 2000 Nobel Prize for Medicine.
One method employed to treat this disease is the transmission of electrical signals to the brain: Batteries implanted in the patient to stimulate nerves increasingly reduce these cells' insensitivity. In this method, known as Deep Brain Stimulation, DBS, a battery-like device sends electrical signals via one of the 100 billion neurons in the brain and triggers the release of chemicals like serotonin or dopamine. This action encourages neighboring cells to send new electrical impulses to other neurons.
But doctors have to be exceptionally careful when implanting the DBS device. A misalignment of just a few millimeters (a few inches) can result in very different results, such as depression.
But in almost all healthy individuals, this system works to perfection without requiring any intervention as to which molecules are to be released, when and in what quantities. The nerve cells' communication system once again confirms a manifest truth. These delicate balances and complex mechanisms in question cannot have come into being through consecutive chance events. It is Allah, the Almighty and Omniscient, Who creates them, gives them to our service and takes them back when He so chooses.
The Body's Data-Perception Network
A magnificent data-perception network permits the muscles to function properly. In order to perform any coordinated action, it is first essential that the positions and interrelations be known of all the organs concerned. This information comes from the eyes, from the inner ear, and from perceptions in the muscles, joints and skin. Billions of units of information are processed and analyzed every second, and new decisions taken accordingly.
The muscles and joints contain billions of tiny micro-receptors, whose messages reach the central nervous system and in the light of the analyses carried out in the nervous system, new commands are given to the muscles. Even when you want to wave to a friend, wide-ranging calculations, comparisons and intense communications all enter your decision to raise your hand. The sequential contraction and expansion of your tricep and bicep muscles, those muscles forward of your elbow that turn your wrist, and the muscles that control your hand and fingers—all are essential. At every stage of this movement, millions of receptors inside the muscles inform the brain of their position. The following instant, the brain tells your muscles exactly what to do next.
In order to lift a spoon to your mouth, you need to bend your arm in the direction of your mouth. After the brain has made that decision, it sends a signal to contract to the muscles that will bend the arm. But before that signal reaches your arm, it's transferred to nerve cells in the spinal column, where electrical circuits perform a number of tasks.
As revealed by our Lord in the verse "We will show them Our Signs on the horizon and within themselves until it is clear to them that it is the truth…" (Surah Fussilat: 53), rational individuals will see the might and knowledge of Allah in every detail they see.
Your god is Allah alone, there is no god but Him. He encompasses all things in His knowledge." (Surah Ta Ha: 98)
The Coordination in Our Bodies Is an Example of Creation
The brain receives messages from receptors all over the body, informing the brain about the position of the arms, legs and all other parts of the body. The brain analyzes this data in order to regulate movement. As a result, you are able to bend over and brush your hair without losing balance and falling over.
There are also receptors inside the muscles and tendons, sending the brain messages about the extension of the muscles and the tension in the tendons. The brain uses this information to tell whether a limb is bent or straight. Sometimes the brain determines the body's position by analyzing commands sent to the muscles. This monitoring system is employed during the process of vision, for instance. Since the eye muscles are in constant motion, the images formed on the retinas are constantly changing place. Yet that is not the case with the image we actually perceive, because as the brain analyzes the image on the retina, it also takes into account the instructions it has issued to the eye muscles. This system is just one of the examples that demonstrate the design perfection created in our bodies by Allah.
Muscle Movement, and the Order in the Acetylcholine Channels
A muscle contracts when the nerve leading to it is stimulated. The stimulus traveling along the nerve triggers the secretion of the messenger molecule acetylcholine, which diffuses in the space between the nerve and the muscle cells and attaches to the acetylcholine receptors in the cells' membrane. This causes the ion channels in all the receptors to open, allowing the electrical current to continue along the muscle cell membrane, resulting in muscle contraction.
One way of halting these events is to use a substance that blocks the acetylcholine receptors, a method used by certain venomous animals to induce paralysis.
Calcium: One of the Minerals Necessary for the Body's Electrical System
Calcium performs a great many vital functions. For example, every cell in your body, especially those in the heart, nerve and muscle cells, requires calcium in order to function normally. The presence of calcium is essential for nerve communications and the regulation of the heartbeat. Calcium also plays a role in the contraction of smooth muscles and in blood clotting. In the absence of calcium, messages will not reach the nerves. Since no external stimulus is transmitted to the nerves, the brain cannot perceive it, and feeling is lost as a result. This results in a person becoming completely paralyzed or the internal organs failing to function, which in turn can spell death. Were it not for calcium, then blood would fail to clot; respiratory functions would cease due to serious muscular contractions, and the rhythm of the heartbeat would be impaired. Generally, we seldom consider whether the body needs such an important mineral. Indeed, you have no idea of the level of calcium in your body during the course of daily life, and cannot calculate your own calcium requirements. That is because our cells have been created with the ability to perform these complex monitoring processes automatically, instead of us having to do them.
There are up to 2 kilograms (4.41 lbs) of calcium in the human body. But only 1% of this is used in essential processes, the rest being stored in our bones. This storage system, which responds to our needs, safeguards the excess for use where necessary without our being aware of it, is just one of the signs of the mercy of our Lord, Who created the human body with very special designs, right down to the most minute detail.
Electrical Order in Muscles of the Digestive System
Every detail in the human body, from a single cell to the hormones it secretes, reveals proofs of Allah's magnificent creation. Examining the features of the digestive system, for instance, we see that the components necessary for the digestion of foodstuffs all possess the most complex structures. And all these components are in constant communication with one another, know when they need to go into action, and can perform all the processes necessary to make nutrients beneficial to the body and for harmful substances to be weeded out.
Different mechanisms allow foodstuffs to travel along the digestive tract. The smooth muscles in the intestines contract involuntarily, and thanks to these muscles' rhythmic contraction, nutrients always progress in a single direction. A team led by Jan D. Huizinga, Ph. D., a researcher for Intestinal Disease Research Program, from McMaster University in Canada, studied the cells that permit this single-direction movement. In their research they located micro-electrodes along the digestive tract. These micro-electrodes determined that the interstitial cells of Cajal set up a constant and regular electrical current, which permits muscles in the intestinal wall, laid out like the links of a chain, to contract one after the other.
On its own, however, the flawless formation of an electrical current is not enough for this mechanism to function. At the same time, the current needs to have a flawless rhythm. For that reason, the cells of Cajal set up a network in the intestines. It is this network that permits them to discharge the electrical current with the same rhythm (Science et Vie, September 1998).
Thanks to this flawless system, the food you eat travels in one direction along the digestive tract, to be converted into a form that is useful to the body. Were it is not for the rhythmic electrical current set up by the cells of Cajal, the intestinal muscles could not contract in such a harmonious manner. That could lead to the food eaten traveling back towards the stomach instead of in a single direction. Yet apart from cases of serious illness, such a distressing situation never arises. As can be seen in this example, the system in the human body created by Allah is flawless in all respects.