THE HEART: THE BODY'S ELECTRONIC CLOCK
One of the factors that keep you alive at this moment is the blood circulating in your veins. In contrast to any other fluids in the body, blood has functions that require intelligence and consciousness. Heading the list of these functions is distributing the energy that trillions of cells require to live. The defense system that protects the body from germs, the system that collects wastes and expels them from the body, repair and maintenance of the tissues, the establishment of communications and regulation of body temperature are all made possible by the blood. The propulsive force that propels this vital fluid to reach every cell in the body is provided by the heart. In order to grasp the importance of the heart's very special pumping system—another component of the body's electrical system— a closer look at the properties of the blood is needed.
BLOOD, THE SOURCE OF HUMAN LIFE, CANNOT HAVE EMERGED BY CHANCE
We are indebted to this fluid that constantly circulates through our bodies, for our living healthy lives. Blood’s most fundamental duty is providing the oxygen that cells need to live, by circulating from the deepest folds of the brain to the outermost layers of our skin. Cells need oxygen to produce energy by breaking down sugar. If blood fails to reach a cell, it suffers oxygen deficiency that leads to the death of that cell.
However, this system functions at every moment and in a flawless manner for each of the 100 trillions cells in the body. In one day, the blood travels a total of 19,000 km (12,000 miles)—that's four times the distance across the US from coast to coast.Five liters (1.3 gallons) of blood must circulate in the veins running through all parts of a body of average weight. If a fifth of this portion, a one-liter quantity, is absent, the remaining blood becomes more difficult to move. If it is unable to fill the veins, then the very fine blood vessels will adhere to one another. Blood circulation will slow, and cells will rapidly begin dying. Cells can withstand oxygen deficiency for only one or two minutes.
The propulsive force that allows the blood to flow to every cell in the body is provided by the heart, with its special pumping system. The heart's most important feature is the way it never stops working. Its special muscles never suffer fatigue. No artificial pump can work for a lifetime without rest and adjust the rate of pumping according to circumstances. This reveals the wisdom of our Lord and the extraordinary nature of the heart's creation.
For this reason, the body’s oxygen needs to be constantly monitored and kept at a fixed level. It is definitely illogical to maintain that blood cells acquired such ability by themselves, as the result of chance and possess the consciousness to perform a series of calculations and constantly fulfill this function flawlessly. This is just one of the many features of the human circulatory system. Blood carries nutrients to cells with wholly different responsibilities, and transports their collected waste products to the kidneys, lungs and liver. It receives hormones secreted by the glands and transmits them to organs in need of them. It keeps the body temperature constant and protects the body when any foreign substance enters. In addition, it carries out all these processes without interruption for an average of 70 years. (For detailed information, see Harun Yahya, The Miracle of the Blood and Heart, Istanbul: Global Publishing, 2007)
On the other hand, the body’s organs need various substances in order to perform their own functions. These substances which are carried by the blood include nutrients such as glucose, amino acids, vitamins and minerals and, most important of all, oxygen. That so, you can once again see the importance the veins stretching all through the body, of blood reaching everywhere in it and flawlessly performing all its duties. These substances carried by the blood are of vital importance to the survival of all the body’s organs.
However, not all organs require the same amount of blood. Those with a high rate of metabolism, for example, require more blood than others. Therefore, there is a regulation in the level of blood transfer that, however, does not function like a pre-programmed machine. In extraordinary circumstances, blood circulation alters its way of working according to the situation. In the event of poisoning, for example, the amount of blood flowing to the poisoned tissues is increased, to increase oxygen and remove as much of the toxins as possible.
Blood is not limited to carrying oxygen and collecting nutrients. It also collects cell wastes and permits them to be expelled from the body. Each one of your trillions of cells produces many waste products, such as carbon dioxide and urea that collect in the blood and could have harmful effects on the body. But urea is removed from the body by being carried to the kidneys, while the carbon dioxide is carried to the lungs, from whence it is expelled.
As you have seen, a very delicate system inside us functions at every moment, according to a flawless plan. But under whose control is it? It is impossible for organs like the heart and liver, consisting of unconscious cells, to accomplish this by themselves. It is equally also impossible for unconscious blood cells to assume such a vital function as constantly carrying oxygen to all the other cells in the body. No doubt that these cells, exhibiting a high level of consciousness that does not belong to them, are working for our survival under the inspiration of Allah. They fulfill the flawless duties assigned to them.
Immune cells are also circulated throughout the body by means of the blood. (For detailed information, see Harun Yahya, The Miracle of the Immune System, New Delhi: Goodword Books, 2001) The white blood cells, which engage in the first action against bacteria or viruses that enter the body, are carried to the specific location of infection by the blood. Antibodies and leucocytes in the blood immediately identify the place where the danger has arisen and immediately reach their target destination with the rapidly flow of blood. Cells carry out a series of conscious, rational actions, such as recognizing the danger, identifying its location, traveling to the region by means of the circulation and immediately initiating a defense. How does the immune system make its decisions, which require intelligent consciousness? How can it determine that dangers are indeed dangers, and learn how to combat them? These are just a few of the questions that leave evolutionists speechless.The cells in the blood stream are only a few microns in size, and consist of water. They have no reasoning ability, sensory organs, nor any other similar attributes. Yet they can determine direction, identify sickly cells, become aware of danger, and eliminate those dangers by acting in concert—all exceedingly conscious actions. It is unreasonable and illogical to assume that all these functions developed spontaneously, as the result of chance. Blood cells too small to be seen with the naked eye, devoid of any capacity for thought or reason, fulfill all these roles, which you cannot do for yourself, with the greatest care and scrupulousness. Clearly, any phenomenon that did arise by chance would inflict damage on the existing order, rather than improving this magnificent system, because even the slightest error in the body’s microbiological system would have exceedingly undesirable consequences.
THE HEART: A MATCHLESS PUMP
The blood reaches every corner of the body by means of the heart, with its dual pumping mechanism. The two left chambers of the heart pumps fresh oxygen-rich blood to the entire body, while the right chambers send returning blood to the lungs for carbon dioxide to be extracted and replaced with oxygen. The left-hand chambers possess thicker muscles, since they pump at a higher pressure in order to send blood to reach the whole body. The heart’s most important feature is how it works non-stop, beating approximately 70 times a minute, 100,000 times a day, and 40 million times a year.36During the course of an average lifetime, it beats more than 2 billion times and pumps enough blood to fill an average of 100 swimming pools.
The heart is a combination consisting of two different pumps. The one on the left pumps oxygenated blood to the body's organs and tissues, , and the one on the right pumps CO2-laden blood directly to the lung, causing all the blood in the body to circulate 1,000 times a day. An adult heart pumps 250 million liters (66,040,000 gallons) of blood over a 70-year life span. ("The Incredible Machine," National Geographic Magazine, Washington D.C., 1986, p. 123)
1. Deoxygenated blood from the head and upper limbs
13. Pulmonary ring
Also exceedingly important is that the heart's indefatigable muscles pump a level of blood that depends on the prevailing circumstances. During sleep, the heart pumps approximately 340 liters (90 gallons) of blood an hour, while during physical activity,—for instance, when running—it increases its tempo to pump around 2,270 liters (560 gallons) of blood an hour.37 That is because our muscles need more oxygen when performing tiring activities. Under such circumstances, the heart increases its working tempo from 70 to 180 times a minute, and the level of blood reaching the tissues can increase five-fold.
No man-made pump can match the heart's ability to work tirelessly for an entire lifetime and to regulate the quantity pumped according to prevailing circumstances. The extraordinary nature of the heart reveals an important fact. Allah created many matchless structures, such as the heart, in the billions of human beings. And as revealed in the Qur'an, this is an easy matter for Him:
Your creation and rising is only like that of a single self. Allah is All-Hearing, All-Seeing. (Surah Luqman: 28)
The heart carries blood and all essential substances to the cells throughout the body, and when it can no longer function, death ensues. Like all other organs in the body, it runs on electricity; but this energy that allows the heart to beat does not come from outside, but is produced with the contraction of the heart muscles. Since the heart consists almost entirely of muscle and beats around 70 times a minute, then an electrical impulse needs to be produced that many times. Its tirelessly contracting muscle cells possess a special creation to work the moment an electrical current reaches them. The heart, which is made up of these special cells, is an engine that creates its own energy. This astonishing system in the heart belongs to our Lord, the Creator of all things.
A MATCHLESS CREATION OF PUMPS AND VALVES
The pumps in the heart consist of two different sets of pumps, an upper and a lower. The smaller and uppermost are known as the atria and the larger, lower ones as the ventricles. For example, when clean blood reaches the left side of the heart it first fills the small, upper atrium. From here it is pumped to the larger ventricle beneath. The large ventricle sends blood to the organs of the body. The same process is carried out in the pumps on the right-hand side of the heart. Between atria and ventricles are one-directional valves that open to let the blood flow pass. When the small atria contracts, these valves open and blood fills the large ventricles. When the ventricles contract, the valves close between them and the atria, and blood is prevented from flowing back in the direction from which it came.
There are similar valves in the large ventricle’s exit. When the large ventricles contract, these valves open and blood is allowed to flow to the body. The moment the contraction stops, however, the valves close, preventing the blood from returning to the heart.
Heart valve open
1. Diastole: During the first phase of the cycle, oxygenated blood enters the left atrium and deoxygenated blood simultaneously enters the right atrium. This blood then flows into the ventricles. By the end of this phase, the ventricles are filled to about 80 percent of capacity.
Heart valve closed
2. Atrial systole: Impulses from the sinoatrial node initiate the second phase of the cycle, during which both atria contract, squeezing any blood that remains in the atria into the ventricles.
Relaxing of the coronary ventricles.
3. Ventricular systole: The ventricles contract during the third phase of the heartbeat sequence. The valves at the exits of both ventricles open and the blood is forced into the aorta and pulmonary artery. As this phase ends, diastole starts again.
Contraction of the heart ventricles.
To the right, the heart valves in open and closed positions.
Contraction of the heart ventricles.
This mechanism is exceptionally reliable. Similar systems are employed in modern pumps today. A pump is a device which propels liquids or gasses in one direction. The valve is a gate-like device that opens or closes in order to control the flow of those liquids or gasses. When you pull the trigger on a water pistol, you compress the water inside it. This causes a small valve inside to close and another outside to open, and the piston is pumped, expelling the water. In the same way, valves in the heart guarantee that blood can be pumped in only one direction.The valves in the veins prevent a backward flow against the force of gravity. When you stand upside down, your blood does not rush to your head, as you might expect. That is prevented by the pumps and valves in the heart. We can compare this situation to the way that valves prevent air from escaping after it has been pumped into a bicycle tire. 38
As you see, the heart has been specially designed for a specific purpose. And where there is design, there is inevitably a conscious, intelligent designer. Even if we cannot actually see the Designer Himself, we can see the evidence for His existence by viewing the design. Similarly, the systems in our bodies also reveal the proofs of the existence of our Lord, Who created them all.
THE HEART'S ELECTRONIC SYSTEM AND GENERATOR
Have you ever wondered what enables your heart to keep beating? How does it work automatically for hours, days and even scores of years? The tireless pumping system works with the electrical energy, as mentioned earlier. The heart transports blood and all the vital materials to the organs and cells thanks to electrical energy. That is the reason why doctors employ electric defibrillators in the event of the heartbeat stopping completely.
The energy that allows the heart to beat does not reach it from the outside. Instead, the heart is an engine that produces its own energy used during its pumping process. Electricity is produced by the contraction of the heart muscles. Conductor cells transmit these electrical signals to the muscle cells that are responsible for pumping blood at approximately 70 times a minute.
The heart begins beating when the human being is still an embryo in the womb, before any nerves have connected the heart to the brain. The heart is able to continue beating even during heart-transplant operations when all the nerves have been severed and the organ is removed from the patient's chest cavity. Under a microscope, a heart cell even continues to beat by itself as long as fresh oxygenated blood can reach it.39That is because there is a generator in the heart cells that produce their own energy.
As you know, in the event of a cut in the energy supply, a generator is a device that can take over and continue producing energy that prevents machinery from halting or being damaged. The heart, one of the most vital organs in the human body, has also been granted a similar form of protection to prevent its coming to harm, since for the heartbeat to stop for even a moment could lead to serious bodily damage, and might even prove fatal. Therefore, the electrical system that keeps the heart working must itself work without interruption.
Scientists investigating its electrical system encouraged some astonishing facts. The heart functions thanks to an ensemble of programmed and systematic electronic circuits, with a great many interconnections. This electronic control-and-management system co-operates with a large number of other organs, from the kidneys to the brain, from the arteries to the hormonal glands. But who or what causes unconscious cells to perform such clearly conscious actions?
Who located the pumps inside the heart and in such an ordered manner?
Who equipped the body with its veins extending from these pumps?
Who ensures that these pumps work unceasingly?
Who tells each auricle and ventricle when and how much blood to pump?
Who created the valves in such a manner as to maintain the direction of blood flow?
Who distinguishes between oxygenated and deoxygenated blood?
Who made the heart cells able to produce their own energy?
Who commands them to beat regularly and in harmony?
The only answer to all these questions, of course, is Almighty Allah, the Lord of the Worlds.
Allah is He Who created the heavens and the Earth and everything between them in six days and then established Himself firmly upon the Throne. You have no protector or intercessor apart from Him. So will you not pay heed? He directs the whole affair from heaven to Earth. . . (Surat as-Sajda: 4-5)
By its special creation, the heart regulates the speed at which it beats. A group of cells known as the SA node produce electrical impulses in the upper part of the right atrium. These impulses spread throughout the heart and allow the four chambers to contract at just the right time. This electrical impulse travels so quickly from one side of the heart to the other that it appears that all the heart's cells are beating at once. This harmony, which is one of the reasons for our survival, is another example of the mercy of our Lord. Allah reveals this in a verse:
So look at the effect of the mercy of Allah, how He brings the dead earth back to life. Truly He is the One Who brings the dead to life. He has power over all things. (Surat ar-Rum: 50)
The SA rhythm is the heart's normal beat, which is 60 to 100 times a minute. It takes 0.03 seconds for the electrical impulse to travel from the SA node to the AV node, and this is known as normal sinus rhythm.
1. SA node, 2.
AV node, 3.
Purkinje fibers, 4.
Normal ECG 5.
Sinus tachycardia, 6.
Ventricular fibrillation, 7.
Mitral stenosis, 8.
Abnormal ECGs 9.
Atrial/ventricular diastole, 10.
HEART CELLS AND ELECTRICITY PRODUCTION
The cells that contract so tirelessly must possess a design that can begin to work the moment electrical current reaches them. The cells must respond to every single signal that reaches them, on an average of 72 times per minute.
If you examine the heart under a microscope, you can count more than a million cells. Exceedingly complex biochemical processes take place in every one of them. Heart cells are nourished by sugar molecules and oxygen coming directly from the lungs. Every cell has its own pumps and channels and is joined to its neighbors by connective tissue.40
Every long, thin cell has a cell membrane that divides the cell from the environment outside and fiber-like proteins that are able to contract. Proteins embedded in the membrane carry important signals or substances from one side of the membrane to the other. In terms of electrical charge, this polarizes the cell, generating a voltage difference between the inside and the outside of the cell. This difference, known as membrane potential, enables certain proteins in the cell membrane, known as ion channels, to function like gates. When they are opened, ions flow in.
As a result of complex interactions of ion pumps and channels, a heart cell contracts thanks to the electrical and chemical differences occurring along the length of its cell membrane. Consider a cell in the heart ventricle as an example. At a state of rest, the membrane potential in any cell is more negatively charged than its external environment. However, the electrical stimulus arriving from the neighboring cell rapidly alters everything. This differential suddenly increases, and the sodium channels quickly open up. In this way, sodium ions (Na+) rapidly enter the cell, triggering the opening of the calcium channels.
When calcium ions (Ca+2) collect around the cell proteins, these contract. At this point, the sodium and calcium channels close and the ion pumps move the ions outside the cell, causing it to return to its original state. In a healthy heart cell, this transition takes place in less than a second.
The events described here are in fact only a very general account of the true state of affairs, which is much more complex in its details. The heartbeat, which requires so many conditions to be met and work together flawlessly, is one of the countless examples introducing us to the knowledge of our Lord.
My Lord encompasses all things in His knowledge, so will you not pay heed? (Surat al-Anam: 80)
Below, appearance of heart cells. Right, coronary tissue.
Heart muscle fibers Nuclei Ion channels Heart cell Receptors Nuclei Signal transmission Signal transmission Gap between cells Cell membrane
Every heart cell produces energy that starts the heartbeat in motion. Each coronary cell acts literally like a living battery, producing electricity by means of two elements found in the blood in large quantities: sodium and potassium. The atoms constituting these elements often lose a negatively charged electron, and thus gain a positive charge. These charged atoms are known as ions.
Heart cells contain a high level of potassium, and the fluid outside the cells is rich in sodium. The cell membrane constantly pumps sodium outside the heart muscles and potassium inside. Since the membrane pumps sodium out faster than potassium is taken in, a positive charge forms outside the cell. When the charge reaches a particular level, the flow is suddenly reversed and sodium ions re-enter the cell. This sudden change triggers an electrical charge, and the heart cell contracts and withdraws.
THE PACEMAKER THAT REGULATES THE SPEED OF THE HEARTBEAT
Production of electricity by the heart cells is not enough by itself. These cells must first combine in the right sequence, but it is still not enough for them merely to join together. These cells must produce electricity together, in a particular rhythm. Each cell must time itself to act every 0.83 of a second, without fail.
Moreover, cells must carry on their activity for an entire lifetime, never tiring. Furthermore, they must know the level of electrical current that will cause the heart to work as a whole, and to produce that current at exactly the right level—neither more nor less.
When spread out thinly on a microscope slide, different heart cells will beat at different speeds. But when combined together, they form a single tissue that behaves as a single entity. Heart cells in the human chest do not beat at different rates; although each one initiates its own beat, they all beat in a rhythmic harmony. The pacemaker in your heart contains an internal clock that regulates the speed at which your heart beats. This pacemaker is actually a collection of cells, but it functions far more perfectly that any electronic device. Using conductive fibers, it distributes the electrical current it produces to every point in the heart muscle. But this electricity proceeds at different but controlled speeds. When both heartbeat and transmission system are working properly, they carry out an ordered and determined distribution of electricity.
The heart possesses a natural battery that regulates the speed at which it beats—a specialized electrical cell node known as the SA node, (for sinus or sinoatrial node), located in the upper part of the right atrium. These cells initiate electrical impulses that stimulate the heart muscles to contract regularly. The SA node produces the electrical stimuli that spread throughout the heart, ensuring that its four chambers all contract at the proper times. This electrical impulse travels from one side of the heart to the other so rapidly that it gives the impression all the cells are beating at once. This rhythm is the heart's normal beat, which is between 60 and 100 times a minute.41 It takes 0.3 of a second for the electrical impulse to move from the SA node to the region known as the AV node located between the atria and ventricles, and this is known as the normal sinus rhythm.42 The AV node is the location of the cells that produce the second electrical current that completes the heartbeat.
A node of tissue known as the SA node in the right atrium of the heart serves like a generator to provide electricity, sending some 72 electrical impulses a minute to the heart of a resting adult. This region produces faster electrical impulses than other tissues. In the event that the SA node is damaged, other sections of the heart's electrical system are able to take over that function, despite beating at a lower speed.
For example, the group of cells known as the atrioventricular fascicle (His bundle) has a speed of 40 to 60 beats a minute. If the SA node is damaged, this tissue can take over the coronary rhythm. The way that such a vital system has been created together with a backup system is just another instance of Allah's protection of man.
The heart's natural battery is the SA node in the right atrium. The heart also contains nerve fibers transmitting electrical signals from the SA node to other parts of the heart. An electrical impulse leaves the SA node and travels directly to the right and left atria, causing them to contract together, all in 0.04 of a second. There is then a delay that allows the atrium to contract and the ventricles to fill with blood. The electrical impulse heads directly for the AV node, and then to the atrioventricular fascicle after which it divides to the right and left and spreads rapidly towards the right and left ventricles, using the Purkinje fibers, and enables them to contract at the same moment.
1. Upper main vein 2. SA node 3. AV node 4.vLeft atrium 5. Right atrium 6. Pulmonary vein 7. Myocardium 8. Lower main vein 9. Outer coronary layer 10. Purkinje fibers 11. Region between ventricles 12. SA node 13. AV node
Just like a sparkplug in an engine, the heart cells fire many times a minute. Each firing passes through a specialized electrical path and stimulates the muscle walls of the heart's four chambers in a specific order. First the upper two chambers of the atria are stimulated, after which there follows a slight delay for the two atria to empty. When the moving electrical current reaches the region between the atria and the ventricles known as the atrioventricular node (or AV node), it slows down a little: The AV node delays the electrical signal by holding onto it for the short space of 1/14 second—an interval of time that is very sensitively adjusted. The AV node's delay gives the atrium time for to contract tightly and send the blood on to the ventricles. This way, the ventricles fill with blood to their maximum capacity before receiving the electrical current, that signals them to pump out their contents. Were it not for this momentary delay, the ventricles would contract before they were entirely filled with blood, and not enough blood would be transmitted to the body.
Following this delay, the electrical signal continues on to stimulate the other ventricular cells 1/16 of a second later. The large ventricle, now filled with large quantities of blood and whose turn has now come, contracts and pumps blood in to the body. All these processes take place in less than one second.43
To sum up, the electrical current first emerges in the upper part of the heart, in the SA node, ensuring that electricity is distributed throughout the heart and that the heart's muscle cells contract as it passes moves.44Yet the situation that comes about is very different from what one would expect under normal conditions. The energy given off by the generator should first stimulate the small atria and then the large ventricles. Yet since the electrical wave moves very quickly, both pumps should contract at almost the same time, and the heart's work would be seriously impaired. Yet this never happens, because all this has been taken into account beforehand. So perfect is the design of the electrical circuit in our hearts that the electrical energy first stimulates the small atria, is kept waiting for a time, and only then stimulates the large ventricles. After the electrical signal has set out, the atria keep it waiting at a specific point until they have fulfilled their functions.
But the heart and blood vessels do more than speed up or slow the blood circulation in response to the body's needs. They carry blood to different tissues to spark off different activities. Extra blood rushes to the stomach when we eat, to our lungs and muscles when we run, and to the brain when we think and speak. The heart and circulatory system combine data just like a computer to meet the body's various needs, and thus respond in a way that no computer can.45
The deceleration or acceleration of the heartbeat generally leads to tightening of the chest and discomfort expressed in the form of palpitations. The abnormal acceleration or deceleration of the heartbeat may result from disruptions in the heart’s electrical signals. In order to understand rapid or slow palpitations, we need to examine how the normal heartbeat comes about and acts throughout the heart.
In cases where the heart cannot make this adjustment, an electronic pacemaker is used to adjust the speed of the heartbeat. However, these artificial devices bring with them a number of drawbacks that require careful attention. They must not enter magnetic fields, and have to be kept away from devices that generate magnetic fields. Yet no such problems are experienced in the heart’s natural pacemaker. How, then, did a group of cells in our bodies determine—and then meet—needs of which we are consciously unaware? This is a precautionary measure in our bodies, a comfort prepared for us beforehand. All this is just one of the signs of the infinite mercy of our Lord.
There is no one in the heavens and Earth who will not come to the All-Merciful as a slave. He has counted them and numbered them precisely. (Surah Maryam: 93-94)
THE FLAWLESS CREATION NEEDED FOR THE HEART TO WORK SHOWS THAT THERE IS NO ROOM FOR CHANCE IN THE CREATION OF MANKIND
QT syndrome is an inherited condition involving defects in the potassium channels in the heart, which impairs the heart's ability to transmit electricity. Those suffering from QT risk sudden death from excessive exercise or even a nightmare.
The heart's electrical activities need to be simultaneous if the organ is to properly perform all its functions. The body's natural pacemaker, which regulates the rhythm of the heartbeat, sends an electrical signal to every cardiac cell for their contractions to begin. In order for the heartbeat to occur, the potassium channels must open and the potassium ions have to be permitted to leave the cell. In QT syndrome, however, as a result of functional defects in these channels, the cells' acquisition of electrical properties for the next beat is delayed. When the heart is stimulated excessively by emotion or exercise, the defective channels don't allow enough potassium to depart, and this electrical irregularity can lead to the sudden death.
THE ATRIOVENTRICULAR NODE: THE HEART'S SPARE GENERATOR
It is exceedingly important that the heartbeat be rhythmical. Defects of the electrical current in the cells alter the starting time and speed of the signal. A signal that begins too early will cause the heart to beat prematurely or else cause an insufficient contraction. In the same way, electrical signals that are slowed down or accelerated will result in a delayed heartbeat, or one that does not take place at all, leading to various heart disorders.
From that point of view, both the functioning of the heart and its design must be flawless. Reserve systems in the heart permit this important rhythm to be discharged without interruption.
As well as slowing down the electric current and regulating the heartbeat and pumping blood to the body, the AV node has the vital function of acting like a reserve generator to replace the main one if anything goes wrong with it. If the SA node is damaged, the AV node takes over the task of regulating the heartbeat’s rhythm. But this spare generator cannot produce signals as strong as those from the original power source—only 40 to 50 signals a minute. But the signals it does produce are still enough to keep the heart working. Indeed, people have been known to live for 20 years even though their heart’s SA node has failed to work for some reason.46
No doubt the presence of such a system in the body shows that it is the work of a Creator possessed of intellect and consciousness. That consciousness and intellect are those of our Almighty Lord Who created the heavens and Earth.
. . . Do you not know that Allah has power over all things? Do you not know that Allah is He to Whom the kingdom of the heavens and the Earth belongs and that, besides Allah, you have no protector and no helper? (Surat al-Baqara: 106-107)
THE ACCELERATOR-BRAKE SYSTEM IN THE HEART'S OPERATIONS
Most people know that their hearts speed up under certain circumstances—as when they quickly climb a staircase, run or become excited. The heartbeat speeds up, returning to its normal rhythm later. However, most people fail to realize what a great miracle this actually is. The speed of the heartbeat is regulated by a natural computer system installed inside the body.
Most people know that their hearts speed up under certain circumstances—as when they quickly climb a staircase, run or become excited. The heartbeat speeds up, returning to its normal rhythm later. However, most people fail to realize what a great miracle this actually is. The speed of the heartbeat is regulated by a natural computer system installed inside the body.47 For that reason, it is of the highest importance that the heart should beat constantly at a regular rhythm. Like a car traveling at a fixed speed, the heart's tempo also needs to be speeded or slowed in certain situations. The "brake pedal" that slows the heart's rhythm is the vagus nerves, and the throttle that speeds it up is the sympathetic nerves.*.48 A messenger molecule called acetylcholine permits the braking action.
The heart normally beats 72 times a minute. In situations that place a strain on the heart, when a person is under stress or running a fever, the SA node speeds up since the tissues need the heart to pump more blood. In this way, the sympathetic nerves raise the blood pressure by narrowing the blood vessels, and the adrenaline glands over the kidneys release the hormones adrenaline and noradrenalin, which increase the speed of the heartbeat. The hormone thyroxin released by the thyroid gland affects the workings of the heart by speeding the metabolism.49The heartbeat can rise to five times its resting level.
The sympathetic nerves speed up the heart like the throttle in an automobile. When the parasympathetic system is needed, it can slow the heartbeat to 40 beats a minute by easing the force with which the heart muscles contract.50When they detect that the blood pressure has risen, receptors in the arteries stimulate the brain by means of the parasympathetic nerves to release the chemical known as acetylcholine. Blood vessels in the heart expand, and thus pressure falls. If the blood vessels carrying clean arterial blood were not wide enough, they might tear and rupture. The skull might then fill with blood as in a stroke, and the individual be crippled by lack of blood reaching the brain.
But how does this assortment of cells know when to beat, and how fast? Who tells them to adjust their speed? And how did they acquire the consciousness with which to carry out such a vital function? How and by whom is the decision to accelerate or decelerate taken? In the human body, there is such perfect regulation and such a network of data-exchange that no artificial processing network can begin to compare with it. This system functions without your knowledge, even at this very moment, showing that it is the product of a superior Intellect and Knowledge. These belong to our Lord; Who is capable of creating whatever He wishes.
Whenever you do something that requires effort, the muscles around the veins accelerate the flow of blood returning to the lungs. This means that more blood flows to the right atrium in the heart. At this instant, the muscles contract. The central nervous system transmits the nerve signals that form as a result of this tension to the medulla oblongata. The medulla analyzes these data and immediately sends a command to the heart, whose accelerator is activated and its rhythm speeded up. More clean, oxygenated blood thus reaches the muscles.
To keep the heart from beating so fast as to damage itself, a special security mechanism is needed. The aortic veins emerging from the left side of the heart contain receptors that measure blood pressure. As the heartbeat speeds up, the pressure of the blood against the aortic wall rises. When this exceeds a particular level, the receptors become aware of the rising pressure and send messages to the spinal cord bulb, which again evaluates the situation and sends a new command to the heart. At this, the rhythm of the heart is slowed, and the blood pressure is lowered.
It is completely incompatible with logic to maintain that unconscious cells know that a too-rapid heartbeat will harm the body and take precautionary measures to prevent it—or that these cells came into being by chance.
The waves of energy that cause the heart to work is initiated by the cell group known as the SA node, and pass, with the help of the artery muscle, to the AV node, and from there to the right and left fibers. A special electrical system ensures these processes. By the will of our Lord, this electrical wave fulfils a vital function in our bodies.
Receptors measure excessive blood pressure and are located in just the right place in the aortic wall.
A line of communication exists between the receptors and the spinal bulb.
The receptors detect the rise in blood pressure and report this to the medulla oblongata.
The spinal bulb analyzes the information that reaches it and grasps the importance of the situation.
Some of the medulla’s cells assume the responsibility of regulating the heartbeat.
These cells decide to send a message to the heart.
They dispatch their message in a way that the muscle cells will understand.
These and many other actions requiring intelligence and consciousness cannot possibly result from the chance cooperation among unconscious atoms. This flawlessly functioning system was created with the knowledge and artistry of our Lord, Who enfolds and surrounds all places.
THE EMERGENCY SIGNAL
The human body sometimes needs to be stronger, more resistant and to exhibit a higher performance than normally. For example, when a person has to defend himself or escape, the heart needs to beat faster and to pump more blood.
In individuals with advanced heart disease, the electrical signals that regulate the pumping between the chambers of the heart become irregular. This makes it hard for the heart to pump blood in a regular manner.
For situations like these, the necessary precautions have been taken, and another system has been installed in the human body. In case of any extraordinary situation, the adrenal glands secrete the hormone adrenaline. In comparison with its size, this hormone molecule makes a very long journey to the heart. Reaching there, the hormone commands the heart cells to contract more speedily. The adrenal cells producing this hormone know which language those heart cells will understand. At the same time, they are aware that the body must be more resilient and therefore, the heart needs to beat faster. The heart cells obey this command and begin beating faster, and in this way, the body is provided with more of the oxygen it needs in emergency situations.
The famous Israeli physicist and molecular biologist Gerald L. Schroeder refers to this special system:
Muscle cells and especially muscle cells of the heart have large numbers of receptors designed to pass adrenaline, a stimulant hormone. At the sensation of danger (sensation did I say? I wonder just which carbon atom is experiencing this emotional trauma?), our reptilian response of fight stimulates the release of large doses of adrenaline in to the blood. Taken up by the heart muscles, the beat increases dramatically, pumping oxygen-rich blood to power hungry muscles in arms and legs. Cells along the small intestine are constructed to absorb glucose, amino acids and fatty acids, the products of food digestion and transport these products to the adjacent bloodstream, where they'll be carried to the membranes of cells. 51
Most heart attacks occur when one of the arteries that nourish the heart with blood becomes blocked. When the muscle cells are deprived of oxygen or nutrients, they become acidic and begin beating spontaneously in an uncontrolled manner. These pulses disturb the rhythmic contractions of the heart. All of this reveals how the heart's design is an example of a superior creation.
As you have seen, it is astonishing how cells made up of unconscious atoms immediately identify this danger, declare a state of emergency, and take the relevant measures. This series of events requires consciousness and cannot, of course, be the work of chance. Our Almighty Lord created all of these cells and inspires in them the knowledge of what to do, and when.
ALL FACTORS MUST BE PRESENT AT ONCE
In order for your heart to work with perfection, it needs electrical signals. In order for those signals to be produced, the sodium, potassium and calcium ions need to be present at particular levels in the blood. Bearing in mind that these levels are regulated by organs such as the kidneys, intestines, stomach and lungs, it's even more evident that such a system cannot be the result of a fictitious mechanism such as evolution.
First of all, there is a technology in the heart far superior to that of any man-made device. But most important of all, is that there would be no purpose for the heart to come into being by chance on its own. Together with the heart, there must be blood vessels thousands of kilometers (miles) in total length, as well as liquid blood to fill those vessels, kidneys to filter the blood, lungs to give oxygen to the blood and absorb carbon dioxide, a digestive system to provide nutrients for the blood, a liver to refine these nutrients, a nervous system to regulate the working of the heart, a brain to manage the body as a whole, a skeletal system to keep the body upright, and a hormonal system to assist the heart's operations—are all present at the same time. The way that all these and thousands of other elements come together in the most harmonious manner possible is one of the many proofs of a flawless Creation.
A pacemaker (a device that regulates the heartbeat) installed in the body
The heart generates special electricity that allows it to beat regularly. Sometimes when people have heart problems, they need a miniature battery to regulate their heartbeat. These devices, known as pacemakers, permit the heart to beat at a regular speed, by sending it small electric shocks. The way that the unconscious cells in the heart combine to discharge such a vital responsibility happens through the mercy of our Lord.