The Digestive System - 1
We ourselves provide the substances necessary for the vital functions in our bodies to continue—in other words, for the functioning of our organs and for the renewal of our cells—from what we eat and drink. However, the meat, bread, fruit or vegetables we consume all has to undergo radical changes, in other words to be digested, in order to be broken down into substances in a form that our bodies can use.
The crude oil that enters a refinery undergoes various processes, as a result of which very different products are obtained. In the same way, nutrients entering the body are turned into very different substances after being digested.
It is the digestion of food that allows a newborn baby weighing between 2 and 3 kilograms (4.5 to 6.5 pounds) to grow into a 1.80-meter (5.9-foot) , 75 to -80 kilogram (165-to 175-pound) adult 20 to 25 years later. The source of this impressive difference in volume is the way in which substances in the food eaten by the child gradually become assimilated by the body. Some of these nutrients provide the necessary energy for living, and others are added to the body and in the form of flesh and bone. Those parts that serve no purpose are expelled from the body.
The digestive system contains the best refinery in the world. The substances taken in by this refining system are first broken down into their raw materials, then sent to be used by the necessary regions of the body. Since the materials, once broken down, are very different from one another, the new substances that emerge are also entirely different.
One can compare the workings of the digestive system to that of an oil refinery. The crude oil that enters a refinery as a raw material is subjected to a number of processes and gradually broken down, as a result of which quite different products are obtained. As the outcome of these complex processes in the refinery is produced, the gasoline that fuels your car, the basic material of the asphalt you walk on and the plastic containers you use. Similarly, very different substances emerge as a result of digestion. However, the biochemical events that take place in your stomach and intestines are far more complex than those in an oil refinery, and come about thanks to a far superior working system. In addition, these events take place not in an industrial refinery equipped with all the latest technology, but in your own body. The food you eat at breakfast is subjected to thousands of chemical processes, without you ever being aware of them while you go about your daily life, attend class in school or walk along the street.
For these chemical processes to take place, a long “conveyor belt” is needed. Special refinery systems need to be located at every point in this channel so that the materials in it can be subjected to change. The channel in question needs to be at least 8 to 10 meters (26 to 33 feet) long.
However, the human body is only an average of 1.70 to 1.80 meters (5.5 to 6 feet) in height. That means that a canal 10 meters (32.8 feet) long needs to be squeezed into a body that is five times shorter than it. This requires a very inventive industrial design. Indeed, the human body has been created with just such a characteristic. The alimentary canal in question (mouth, esophagus, stomach, small and large intestines) has been situated within the human body in line with a very special arrangement, under which a 10 meter (32.8 feet) canal has been carefully packaged into a body only 1.70 meters (5.5 feet) long.
After entering the body, consumed foodstuffs embark on a 10- meter journey through the digestive system, during which these foods are subjected to a series of mechanical and chemical processes. As they pass through the five-part, 10-meter (32.8-foot) canal, they are broken down by means of mechanical processes such as grinding, kneading and rinsing, and to chemical effects performed by liquids secreted into the canal by various glands.
Digestion has begun in the mouth and continues in the stomach and small intestine. In the small intestine, the useful substances in foods are dissolved for transportation in the blood vessels.
The Refinery’s Entrance
As soon as you place food in your mouth, the digestive system goes into action. The food is broken down and ground up by the teeth, which have been specially created with this process in mind. They are covered in the hardest known natural material—enamel—and are also very resistant to corrosive chemicals.
Every tooth has a shape appropriate to its function. The front teeth are sharp and can break loose pieces of food. Canine teeth are pointed, and slice up the food. The molars have been created to grind the food down. If the teeth in our mouths were all of the same sort—if we had 32 canine teeth or 32 incisors—we would find it almost impossible to eat.
Another example of the creation in the teeth can be seen in their arrangement. Every tooth is in exactly the right place. Incisors are at the front, where they need to be, and the molars are in the back—again in just the right position. If they were to change places, they would become effectively useless.
There is also complete harmony between the independent upper and lower teeth. The teeth in both regions have been so created as to sit comfortably against one another when your jaw is closed. For example, if just one of your molars were longer than the others or had an excess protrusions, you would be unable to close your mouth. You would then be unable to fulfill such basic actions as eating or speaking.
Newborn babies have no teeth in their mouths. But they have no need of them in their early days since their first food consists of their mother’s milk. Gradually, however, as the time comes for them to eat solid foods, various changes take place in babies’ soft palates. Some cells here suddenly begin storing calcium, as if they had received a signal. Later, these millions of cells combine together in complete order and set themselves out, one on top of and side by side each other, as if they know what they must do. Cells that have stored excess calcium later die, and these dead cells constitute the body of the teeth.
The teeth play an important role in the digestion process. Above can be seen 1) the teeth of a newborn baby, 2) the teeth of nine-year-old child, 3) the jawbone and teeth of an adult.
After the millions of cells have stored their calcium, they clump together, side by side, to form a large block. Again, the cells constituting this block determine its shape. At this point, another great miracle of creation can be perceived. For example, the cells in the bottom jawbone know what kind of shape the cells far away from them in the upper palate will construct. Both groups of cells construct their overall blocks in such a manner that they will fit together in the most ideal way. Thus when the jaw is closed, the molars on top sit squarely against those on the bottom.
Any disharmony in this form would cause you great discomfort. However, thanks to the unbelievable consciousness exhibited by the cells in the palate, the 32 calcium blocks are constructed in the most ideal forms for one another.
Details such as the resistant structure of teeth, the way they are set out, and how their shapes and functions complement one another shows the evident creation in them. There is only one reason for the conscious actions of these cells. Like all the cells in the body, it is Almighty Allah Who gives to the cells that comprise the teeth their properties.
THE PROTECTIVE BACTERIA IN YOUR BODY
In recent years, new bacteria active in the human body have been discovered in the rear part of the tongue. Their function is to kill harmful germs in the stomach. However, to kill them is not as easy as you might expect. Bacteria merely carry out chemical synthesis, and there are many aspects to their activity. Just like a chain of dominoes knocking one another over, it is sufficient for just factor one to be lacking for the whole process to come to a halt, because just as with dominoes, every component works by affecting the later ones. The system required to set the bacteria in motion can be summarized as follows:
The nitrate found in green leafy vegetables is turned into nitrite by bacteria in clefts at the back of the tongue, where oxygen does not reach. Then, when the nitrite produced meets the acid in the saliva, it changes to nitric oxide, which has the effect of killing germs.
Professor Nigel Benjamin of Aberdeen University in Scotland, who discovered the bacteria, describes them in this way:
Bakteriyi bulan İskoçya Aberdeen Fakültesi'nden Prof. Nigel Benjamin bu bakterileri şöyle tanımlıyor:
We knew that nitric oxide is quite toxic to some bacteria, so we said hey, what may be happening is that nitrite is deliberately being made in the mouth so that it mixes up with the food we eat and gets acidified, which will generate lots of nitric oxide, which will then kill all the nasty germs we eat with our food. ** Sarah Richardson, “Tongue Bugs,” Discover, Vol.16, October 1995, Issue 10.
Scientists discovered the existence of these bacteria only very recently. However, these bacteria, protecting us from acids by producing nitrites, have been in existence ever since human beings were first created. These are some examples of Allah’s infinite affection for us. Everyone must give thanks for these blessings.
If you tried to number Allah’s blessings, you could never count them. Allah is Ever-Forgiving, Most Merciful. (Surat an-Nahl: 18)
Special Digestive Fluid
You cannot taste food if your mouth is dry, because it is your saliva that permits you to experience flavors. Above, the salivary glands and the muscles that act during chewing. Saliva, which one is generally unaware of, is created by Allah as a blessing.
As food is ground up by the teeth, it also undergoes a special chemical attack, carried out by the saliva.
People are seldom much aware of this fluid in their daily lives, and people do not generally consider whether or not it is secreted, nor in what quantities. Saliva is believed to be a very simple fluid, when in fact it is a most special compound, containing specific levels of various chemicals.
First of all, saliva permits you to taste your food. The flavor-giving molecules in food dissolve in saliva and combine with the taste-receptor nerve endings on your tongue. Only in this way can you actually taste what you are eating. That’s also the reason why you cannot taste food when your mouth is dry.
Saliva is secreted by three different glands, and makes it easier to swallow food by moistening it, as well as containing chemical substances that dissolve what we eat into particles of benefit to the body. In the saliva itself are two different fluids with very different properties. One thoroughly breaks down carbohydrates and turns them partially into sugar. For example, if you place a piece of bread—a carbohydrate—in your mouth and wait for a minute, you will taste the sugar of the broken-down carbohydrate. The other saliva fluid is very dense. Thanks to this liquid’s stickiness, the particles of food that spread around the mouth as we chew are brought together in a kind of paste.
If saliva were not secreted, our food would be too dry for us to swallow, and we could neither swallow it, nor speak properly. We would be unable to consume any solids, and would have to feed ourselves solely on liquids—which would make life rather difficult.
Our mouths work just like chemical laboratories in breaking down the starch in what we eat. The enzyme known as ptyalin in saliva is especially produced for this purpose, to break down the starch and turn it into sugar.
The digestion taking place in the mouth is not only chemical. Mechanical digestion is also performed by the teeth. These two forms of digestion complement each other.
The Role of the Tongue in Digestion
The different taste zones in the tongue (right).
The taste buds in the tongue are flavor-perceiving cells. There are large numbers of taste buds in the round protrusions. The papillae merely enable the food to move.
In mechanical digestion, the tongue plays an important role. It possesses a very sensitive sense of taste, and also directs food in the mouth, enabling it to be chewed and swallowed easily.
On the surface and sides of the tongue are some 10,000 or so taste buds, which are sensitive to four different tastes: hot, sweet, salty and bitter. 28 These taste buds allow you to distinguish the flavors of the dozens of different foods you consume every day. They work so well that the tongue can also distinguish the tastes of foods it has never encountered before. That is why a watermelon never tastes bitter to us in the way a grapefruit does, and why a piece of cake never tastes salty. In addition, the taste buds in billions of different people perceive the flavors of food in exactly the same way. The concepts of sweet, salty and bitter are the same for everyone. Scientists describe the tongue’s ability as “extraordinary chemical technology.”
But what would happen if there were fewer taste buds on your tongue?
For one thing, you would be unable to taste what you were eating. You would be oblivious to the taste of puddings, roast meats or bread. Whatever you ate would all taste the same. Dining would cease being a pleasurable blessing and would instead become a chore you had to perform several times every day. Yet that does not happen, and thanks to your taste buds, you can distinguish the flavors of everything you eat, which allows you to enjoy your food.
In the second stage of the digestive process, food passes through the throat to the stomach, where major digestion will begin. No digestive process takes place during food’s passage down the esophagus. After you swallow, the flat muscles behind the neck push the food into the esophagus. Food is passed down by gravity, as well as of the rhythmic contraction of the esophagus, known as peristalsis. These muscular contractions are so powerful that they enable food to be propelled sideways even if you are lying down. 29 It takes a mere 12 seconds for food to pass through the 25-centimeter (10-inch) long esophagus.
People can use their mouths both for eating and for breathing, because immediately next to the esophagus, down which the food passes, is another tube through which the lungs inhale air. One vital point to be borne in mind here is that if chewed food entered the windpipe instead of the esophagus, you would choke to death. If a piece of food were mistakenly to enter the windpipe, swift death or serious infection would be the consequence. Nor is it any solution for the windpipe to be constantly kept closed. The most rational and practical solution is for the windpipe to feature a valve that can open and close. And so, even when not eating, however, people actually swallow hundreds of times every day—when they swallow saliva, for example.
Foodstuffs passing down the esophagus begin moving towards the stomach. Very powerful, rhythmic muscular contractions known as peristalsis permit foodstuffs to move along the alimentary canal.
As already stated, the human body’s creation is perfect, and the windpipe possesses a most reliable security system. A valve consisting of a small piece of tissue at the top of the windpipe automatically closes as you swallow, preventing any food or drink from entering the windpipe. After an act of swallowing has taken place, the valve opens in its former position, and air can once again be inhaled through the windpipe.
As people eat in their daily lives, nobody is aware of this potential danger. No one ever thinks, “What if what I swallow goes down the wrong way? I wish I had a valve in my windpipe so my food would never get stuck in it.” Neither do people often wonder, “Is that valve working and able to stop me from choking?” In all probability, you were unaware of the importance of the valve in your throat until you read these very lines! However, that valve’s existence keeps you alive at all times, even as you swallowed unconsciously, just a few seconds ago.
This valve’s evident feature contains a great many details. For example, were a normal adult’s valve the same as a baby’s, that baby would be in serious danger. For that reason, babies’ valves function in a very different way. Their little valve is located higher up in the throat than it is in adults, allowing babies to breathe as they drink their mothers’ milk. That is also why babies do not cry and choke as they nurse. If the valve system in babies were the same as that in adults, then babies might choke unless they held their breath.
However, this same need has existed in every baby who ever lived, and exists in every baby alive today—and is met in the most ideal manner. Apart from those suffering from a specific disorder, everyone was endowed with just the kind of valve they required in infancy. In the same way, when these people become youngsters, the structure of that valve again changes to respond to their different nutritional needs.
A small valve of tissue on the esophagus automatically closes the windpipe when swallowing. Food or water are thus prevented from entering the windpipe when you eat. After swallowing the valve opens again and air can move through the windpipe.