Politicians and anti-Muslim activists frequently take to audiences and websites to criticize the term jihad as a form of Islamic supremacism, oppression, and violence. Muslim extremists, on the other hand, argue that jihad refers to a “holy war” against non-Muslims. Viewing the term jihad through these frameworks alone, however, would be playing into the hands of extremists who forego the other elements encompassed by the term jihad.

In the Islamic tradition, jihad has several different components, including personal struggles, such as the fight against an addiction; social struggles, such as the struggle to become tolerant of others; and occasionally a military struggle, if and when necessary, but only in self-defense. When asked, “What is the major jihad?” Muhammad replied: “The jihad of the self (or the struggle against the personal self).” Contrary to the rhetoric and misinformation about jihad in anti-Islam networks, Muhammad did not say that the violent struggle was the most important form of jihad.

The hysteria in the United States and abroad over jihad has brought me to consider the term through a Christian perspective. In this article, I hope to explore how forms of jihad are presented in Islam and Christianity. This exercise can help to find common characteristics of jihad so that Muslims and Christians can build bridges of mutual understanding and tolerance.

Although the term jihad is not literally used in Christian scripture, the idea of struggling is at the very heart of Christianity. There are a number of instances in the New Testament which provide guidance for Christians who are struggling with different problems or dilemmas in their lives.

One major aspect of the Christian jihad is the practice of non-violence. When the Roman soldiers arrested Jesus and brought him to Pontius Pilate, the man who contributed to Jesus’s crucifixion, Christ said: “My kingdom is not of this world. If it were, my [disciples] would fight to prevent my arrest by the Jews. But now my kingdom is from another place” (John 18: 35-36). Violence is antithetical to Jesus’s teachings. He did not require his followers to take up arms to show commitment to his teachings. Indeed, it was quite the opposite. In Matthew (26:53), Jesus told his followers that “… for all who take the sword will perish by the sword.” Jesus, as you can see, encouraged his disciples to struggle against the desire to use force when frustrated or antagonized. 

Similarly, Islamic scripture also encourages Muslims to struggle against the use of violence. The Qur’an (5:32), for example, notes that “…. If anyone slew a person unless it be for murder or for spreading mischief in the land it would be as if he slew the whole humanity: and if anyone saved a life it would be as if he saved the life of the whole humanity.” In another Qur’anic passage (2:190), Muslims are told to “Fight in the case of God those who start fighting you, but do not transgress limits (or start the attack); for God loveth not transgressors.” It is clear that these two passages echo the Christian jihad of struggling in the name of non-violence.

Another element of the Christian jihad is to show love to those around you. Jesus wants Christians to “love your neighbor” and even beyond that, “love your enemies,” a point which arises in Luke (6:27). In Matthew (5:9), it is written that peacemakers are blessed, “for they will be called sons of God.” The New Testament demands that Christians struggle in the fight for peace, even if it means embracing your sworn enemies and those who wish to harm you.

The Qur’an also requires that Muslims search for ways of making peace instead of war. Muslims, for example, are required to speak well of others even if they are not believers of Islam. In the Qur’an (17:53-54), it is written that Muslims must “speak in a most kindly manner (unto those who do not share [your] beliefs).” There is also no way a Muslim can force others to believe in Islam, as the Qur’an (2:256) mentions that “there is no compulsion in religion.” The jihad in these contexts is one in which Muslims have to work on treating non-Muslims with respect and dignity.

The Christian jihad also requires that Christians do not retaliate “evil for evil.” Romans (12:17) demands that Christians “live at peace with everyone.” People who call themselves Christians, yet call for the demise of Islam and anything related to Muslims, should heed the demand of this verse and search for ways to build bridges for peace instead of fanning the flames of hatred and bigotry. In a similar way, Muslims who call for violent jihad should remember that the Qur’an (4:9) asks Muslims to leave others alone if they leave Muslims alone: “refrain from fighting… and offer [them] peace, then God gives you no way to go against them.”

The Christian jihad can be explored further in the wisdom left by Jesus’ disciples. Peter, for example, is considered “the rock” of Jesus’ church because he spoke about the struggle to maintain the Christian faith at all costs. In 2 Peter (3:14), he stated “… make every effort to be found spotless, blameless and at peace with [Jesus].” In this verse, Peter is highlighting one of the ultimate aims of Christianity — avoid wrongdoing and sin. A true Christian, such as Peter, cared more for fixing his own transgressions rather than attacking others for their sins. He encouraged Christians to struggle with overcoming their personal dilemmas first before bickering and complaining over the errors of others. In essence, he believed progress is rooted in individuals’s ability to change their attitude and behavior in struggling to adhere to the teachings of Jesus.

In addition to Peter, Paul of Tarsus also embraced the Christian jihad. Paul made “every effort to do what leads to peace” (Romans 14:19). In Timothy (6:12), he encouraged Christians to “fight the good fight of the faith,” which can be interpreted as spreading peace and love in the spirit of Jesus. In addition, in 2 Timothy (4:7), Paul stated, “I have fought the good fight, I have finished the race. I have kept the faith.” There is an underlying non-violent tone in these statements. Never did Paul ask Christians to take up the sword or use violence as a means of showing faith in Jesus.

Moreover, in 2 Peter (1:5-7), Peter stated that a Christian must “make every effort to add to your faith goodness; and to goodness, knowledge; and to knowledge, self-control and to self-control, perseverance; and to perseverance; godliness; and to godliness, brotherly kindness; and to brotherly kindness, love.” Peter’s emphasis on doing good and searching for knowledge mirrors the Qur’an’s frequent emphasis on ilm, which means “knowledge” in Arabic. Indeed, few religions in the world place so much emphasis on knowledge as Islam. “Knowledge” is mentioned more than 700 times in the Qur’an.

In the Qur’an (58:11), God raises in rank “… those who have been given knowledge.” Muhammad also emphasized knowledge in a Hadith in which he said that “seeking knowledge is a must for every Muslim, male or female, from cradle to grave in any part of the world.” Muhammad also stated in another Hadith that “the ink of the scholar is more sacred than the blood of the martyr.” Christians and Muslims, therefore, share a similar jihad in terms of their obligation to seek out knowledge and apply that knowledge in good faith for the betterment of humanity. 

Jesus, like Muhammad, taught his disciples and future believers that struggling is a fundamental element of the Christian faith. He told his disciples to “strive to enter in at the narrow gate…,” which mirrors the popular Muslim notion of staying on the “straight path” or practicing Islam to the best of one’s ability. Ultimately, Christians and Muslims are guided by their scripture to persevere in the face of their struggles. They are encouraged to struggle in this life, to maintain belief in God, in exchange for a higher reward when this life inevitably ends.

In essence, Christians and Muslims share a similar jihad. This jihad is one of non-violence, the love of humanity, the perfection of the soul, and the search for knowledge.

White blood cells (leukocytes) are fewer in number and their duty is to fight against germs. How this process works is to be expounded by the immune system under a separate title. The red blood cells are my main building blocks and they are born by the dividing of the main cells in the bone marrow. After passing through a few phases, they lose their nucleus and are filled instead with hemoglobin, a magnificent substance containing iron. Hemoglobin’s most vital function is its binding oxygen and then carbon dioxide after releasing it. Hemoglobin reaches everywhere, traveling with the blood stream. When it comes to the lungs, hemoglobin dumps the carbon dioxide and replaces is with oxygen. Then it supplies this oxygen to the cells and removes the carbon dioxide, which is produced by burning organic compounds. So its short life passes with the same ceaseless cycle to continue your life. Hemoglobin molecules’ longevity is approximately 120 days. They contain no cell elements like ribosome, mitochondria, and nucleus and therefore cannot repair themselves. They simply die when they get old. Sad? Not at all! Red blood cells fulfill the duty they were created for and leave the stage for new ones. They are broken down in the liver and bone marrow and the iron they contain is absorbed. A certain part is transformed into bilirubin, giving bile its yellow color. As you see, nothing is truly wasted.

The red blood cells in circulation number around 25 trillion, and this number does not vary greatly, as the dying ones are constantly replaced. Their measuring gives doctors an idea about possible diseases. The amount depends on various factors’ reciprocal balance. A hormone (erythropoietin) secreted by the kidneys increases the rate of production of red blood cells, in response to falling levels of oxygen in the tissues. If you lose blood due to an accident or medical operation, the stem cells in the bone marrow receive an emergency alert to produce more red blood cells. On the other hand, if you get a blood transfer, stem cells are ordered to stop producing, due to the excess of red blood cells. You see, even such basic knowledge about bodily systems fills the learner with wonder.

Deficiency of red blood cells, scientifically known as anemia, should not be ignored. It results in pallor and weariness; you feel like sleeping more. In order to avoid this condition, your body needs different things such as group B vitamins (B6, B11, B12), vitamin C, amino acids, and iron. Since it is hard to pinpoint the deficient substance, doctors generally prescribe iron-rich multivitamin supplements.

Red blood cells divide into four types, which determine the blood groups A, B, 0, and AB. In addition to the blood group, another feature known as Rh (rhesus) factor is important to know particularly before a blood transfer. Transferring the wrong type of blood may result in death.

Platelets, which are scale-shaped cells and circulate with me are not independent; they are pieces which came off bigger cells. In a cubic millimeter of blood, 250 to 350 thousand of these little scales are found and their duty is of vital importance. If it weren’t for these pieces, the slightest cut could cause death because your bleeding would not stop. Clotting is a great blessing. It usually blocks the surface of a wound within five minutes, stopping the flow of blood and saving your life. Clotting is realized through particular molecules in these minute scales as a result of a complex chain of reactions using enzymes, vitamins, and salts. Every step of this chain of reactions is another stitch to fix the wound. Other blood cells pile up and stick together behind this net and they dry up. If such clotting occurred inside the blood vessels, it would make a disastrous effect by blocking the bloodstream. I also have enzymes to break down little amounts of such clotting. As you see, everything is splendidly organized.

Peter! A blood test reveals very critical medical data. As I visit every organ, I exchange certain substances with them. Therefore, detection of an unusual substance in me can be an early warning for a disease. Nowadays, it even helps an early diagnosis of cancer.

It is not so easy for me to explain the wisdom behind all of my duties and capabilities. But to give you an idea, there are specialized departments for studying just me at medical faculties and research institutions throughout the world.

We vessels can be divided into three main groups in terms of structure and function. The ones with thicker walls, which bring every organ the blood they need from the heart, are the arteries. The pressure inside us is higher and we easily carry blood to the organs. The ones with thinner walls, lower pressure, and larger inner space are called veins. As a matter of fact, both arteries and veins have a three-layered structure that is very suitable for holding a fluid like blood. Since our walls are strengthened with both connective tissue and smooth muscle layers, we bear the pressure coming from the heart and help blood proceed by contracting and relaxing. Since arteries are directly subjected to the strong pressure from the heart, our walls were created in a thicker and stronger form. Since the veins return blood to the heart and thus have lower pressure, we have valves that close after blood passes, so it does not flow backward due to gravity. This is a serious challenge for the blood passing through your legs. Varicose veins might develop due to weight gain from pregnancy or obesity, which increases pressure on the legs, or to hours of standing, walking, or running on hard surfaces.

Capillaries are the most delicate blood vessels, with walls made of a single layer of epithelium, which enables us to exchange substances between blood and tissues. As blood vessels, our total length is about 120,000 kilometers. Try to imagine if a fisherman’s net were made from a rope of this length and how wide it would be! And yet, such a vast network of blood vessels is located in your body, and capillaries take blood to every part, without neglecting an area as tiny as the head of a pin.

The well-being of your organs is directly related to us. If our interiors begin to narrow, because of fatty cholesterol plaque for instance, then we begin to lose our flexibility. This means malnutrition for that organ, since a lesser amount of blood than expected can come. If a blood clot sticks to our wall and blocks the blood flow, the relevant organ may be in terrible trouble. If other arteries supply blood to that organ, then it can handle this, but if a main artery is blocked and if secondary channels do not exist or are insufficient, you experience infarction. Taking this into consideration, you need to be careful what you eat and lead a physically active life. When you get old, if sufficient blood does not pass through us in your brain, failures with brain activities appear and you go senile. As the walls of veins and arteries have a rich network of nerves, we let the suitable amount of blood flow according to the need of the organ we’re serving, under the control of the autonomous nervous system. While blood vessels that are connected to an organ not currently requiring much blood contract to reduce the amount supplied, those that are connected to currently more active organs expand. And dear Peter, the greatest blessing here is that none of these activities require any conscious effort from you; everything works smoothly without your even being aware.

This wonderful network of ours finds its value in the vital fluid we carry. If it weren’t for blood, we would have no value at all, and such a perfect means of distribution would be unnecessary. Even the duty of the heart is to make this fluid circulate throughout the body. Now, let us step aside and allow blood to have the floor.

All the organs functioning in your body have a direct or indirect relationship with me. I can be compared to a kind of “chemical brain.” All metabolic activities are among my duties, including the control of excretions, digestion, and the composition of blood. You would be stupefied if I listed every single function I carry out, but let me tell you this much: biochemists have discovered that I am directly included in more than 80 different activities and related to more than 5,000 chemical reactions taking place in your body. Surprised? But this is only what they’ve learned so far; you do not know me in detail yet. My plain appearance is in contrast with my numerous functions. My size is about one-tenth of the body of a six-month-old fetus; now that you have become a young man, I weigh about one fiftieth of your body weight. Since I am the largest excretory organ in your body, I am firmly strapped with mesentery so you can run, jump, and make other movements without trouble.

Most people see me merely as a bile-producing organ, which happens to be among the simplest of my duties. Let me explain it another way: the heat I produce while working is equal to one-third of the heat your body produces while resting. I have a special circulatory system. Since I am located at a “junction,” the blood coming from the intestines which bear nutrient molecules come to my vein first together with the blood from the spleen, before joining the rest of the bloodstream. It can be compared to an obligatory customs check. The amount of blood I supervise within 24 hours is about 2,000 liters. With every heartbeat, almost 28 percent of the blood being pumped passes through me.

I adjust the level of blood sugar in a very sensitive balance. If you eat desserts or pastries I convert excess sugar into glycogen (animal starch) and store it. If your blood sugar decreases from hunger, I break down glycogen into sugar (glucose) and come to your help so that you do not come to a halt, like a car out of fuel.

I use various protein molecules to synthesize numerous enzymes. I also play a role in blood coagulation, red blood cell production, and storing the iron you need. You know, nothing is wasted in the divine system of nature. So how can I waste anything? When the aged red blood cells die, I help the spleen to break them down and store the iron they contain. My job in fat metabolism is no less important. Thanks to the bile I produce, the fatty food you eat is broken down to smaller molecules to be absorbed in a way similar to detergents remove oily remnants from dishes. Naturally, the fat-soluble vitamins (A, D, E, K) are also absorbed along the process. I store the excess of both these vitamins and fats. Fats are an important fuel particularly for your heart muscles. I excrete an average of 600–700 grams of bile a day. Two minutes after oily foods pass to duodenum the walls of my gallbladder are operated. Through contractions of 2–6 times a minute and a pressure of 25–30 mmHg, the bile is passed to duodenum in a time span of 15 to 90 minutes. What gives bile its yellowish-green color is the substance named bilirubin, which appears with the breaking down of the old red blood cells and disposed of through the bowels.

The Kuppffer cells—as you name them—have the duty of checking out newly produced blood cells one by one in addition to producing antibodies against germs. If any ill-formed blood cells come up, I must detect and destroy them. Otherwise they corrupt your blood. Thanks to the Kuppffer cells, the ill-formed blood cells are destroyed as soon as they are detected.

The average longevity of my cells varies between 150-180 days (220 days maximum). New cells are produced immediately to replace the dying ones and the system works smoothly. In each of these cells there are 1,000-3,000 mitochondria and millions of ribosome. An average of 180 new ribosome are produced every second. Although none of my cells have consciousness or intelligence, thousands of them come together to form little lobes resembling hexagons. The number of these lobes varies between 50,000 to 100,000.

Dear Peter, you intake various toxic substances together with the foods you eat. You don’t even realize that food has been corrupted by bacteria and fungi until its taste changes. Frankly, you should not have lived very long with so much toxic intake; Providence has given me an important duty to protect you from such harm. I capture these toxic compounds released into your bloodstream and neutralize them. The same goes for different medicines you take; I try to neutralize their toxic effects as well. But I have my own limits of tolerance; if I am faced with more toxic substances than I can handle, then I give signals of danger. You wonder how. Well, I shout “help” through red spots in your hands and itchy spots on your skin. You should be more careful about what goes down your throat.

Given that I fulfill various important functions, the littlest failure in me reveals itself as a health problem immediately. Hepatitis is among the common diseases heralding my failure. Excessive increase of bilirubin in your blood causes the white of your eye and your skin to turn yellow. I fear viruses most. Particularly hepatitis B and C viruses destroy my tissue. And alcohol, as you know, is my sworn enemy. I have to exert myself to neutralize even a tiny amount of alcohol. And if the hepatitis virus is added, I become knocked down and contract cirrhosis. It does not happen suddenly, though. Along the process which you know as liver failure I give various signals: skin eruption, digestion problems, sleepiness, and headache after meals, and so on. Since these symptoms are not serious problems, most people ignore these signals I give. Due to my various functions, the lab tests about me are more than a hundred.

Talking about my enemies may have upset you a bit, but it’s not all doom and gloom. After all, I am the organ with the highest capacity to renew itself. Sounds good, right? Otherwise I would have been finished off long ago, so this ability is a real blessing. Let me give you an example: although 90 percent of my cells are destroyed during hepatitis, I can help you survive with the remaining 10 percent if you rest well and control what you eat. If you ignore the disease, it might lead you and me to the grave. Do not ever believe those who take this lightly and say: “This doctor says that a small amount of alcohol is good for health.” Tell it to the marines. Those who say that should visit hospitals first. I’m sorry, Peter, but it really gets on my nerves. If they could only appreciate a work of art like me. Anyway, that’s all for now, please take good care of me.

I hang between your stomach and your duodenum under it, attached to the intestinal mesenteries. I have two different identities in terms of my structure and function. I carry out two very different duties as a compound gland made up of both exocrine and endocrine tissues. So, I am granted a very special structure and chemical abilities to function well. One of my duties is related to the physiology of digestion: I break up the food passing from the stomach to the duodenum by pouring on it the four types of digestive enzymes I have been enabled to produce. These juices are carried through a tiny pipe to your duodenum. Two of them are used for breaking up proteins, one for carbohydrates, and one for fats. You don’t even realize it! As the food you take in passes from the stomach to the duodenum, my enzymes begin flowing faster. This is a very fine balance: while food is being digested, neither the enzymes should be wasted, nor should your intestinal walls be harmed. I don’t control the release of the enzymes. That duty is given to two hormones produced in your intestinal mucosa by the stimulus of the vagus nerve. When those hormones reach me by the bloodstream, my cells are stimulated and they secrete water, bicarbonate, and the digestive enzymes I mentioned and they flow into your duodenum through my duct.

My second job is the production of insulin and glucagon hormones, as the endocrinal pancreas. My cell clusters, which are also known as islets of Langerhans, have different types as separate groups, which you call alpha and beta. The insulin, which is produced by my beta cells, is used for regulating the glucose level in your blood. The duty of insulin is to stimulate your body cells to take the glucose in your blood and use it.

After you have a meal, the carbohydrates in it are broken down into glucose molecules, pass into the blood, and increase your blood sugar. For your body to function in a healthy way, the amount of glucose should be around 100mg/ml (it varies from 80–120). When the level is above the normal value, I secrete insulin. In this way, the sugar is carried to your cells and burned to produce energy, and its increase in your blood is brought back under control. Also, insulin helps you to store sugar in fat tissues and to turn them into fatty acids, and it slows the breaking down of fatty acids. Moreover, insulin helps you to make protein in your body by holding amino acids within your muscle tissues and storing glucose in your liver and turning it into glycogen.

The failure of my beta cells to secrete insulin is a serious problem; the consequence is “diabetus mellitus,” or what we commonly know as diabetes. A person with this disorder must abstain from various delicious foods and drinks. In cases where a strict diet does not solve the problem, patients may have to take insulin shots every day. Diabetes can cause many complications by damaging your nerves and blood vessels; I won’t go into types of diabetes so I don’t get sidetracked too much. I just wished to make a point: even a substance produced by a tiny cluster of cells can upset the functioning of many of your mechanisms. After having a meal, put your hand to the left of your abdomen below the stomach and remember what a blessing I am!

As for the glucagon hormone I secrete from my alpha cells, it does just the opposite of insulin and causes the sugar stored in your cells to be released into your bloodstream. When your blood sugar decreases-due to hunger, overwork, exercise, and so on-it causes the glycogen in your liver to be used in order to increase the level of your blood sugar. As adrenalin secreted by the adrenal glands helps glycogen to be broken down and to be released into the blood as glucose, they function as an integrated system. Glucagon also slows down the synthesis of glycogen, and it accelerates the break-up of proteins and fat metabolism. I think now you get it, Peter. Insulin and glycagon are parts of a biological feedback mechanism controlling one another. People discovered all these facts after years of lab research; now do you see how ridiculous it is to see me as a work of blind chance?

Like any other organ, I can also contract various diseases. The most common ones are acute or chronic inflammation, tumors, and cysts. I am easily troubled with inflammation in people with alcohol habits. Since enzyme secretions-and therefore digestive processes-are then not carried out properly, some undigested fats and fibers with proteins are excreted with the feces. A problem can arise with the intestines due to digestive deficiency. And if I completely fail to fulfill my duty owing to a chronic inflammation or tumor, then doctors take me out and you become dependent on insulin and a special liquid obtained from the pancreas.

It is sad to say that my cancer is not quickly recognized. It develops very fast and I try to keep up my duty as long as possible. Therefore, it is usually too late when diagnosed. There is nothing much modern medicine can do after it spreads. Although it is not definite yet, I suspect cigarettes play a role in my cancer.

As for diabetes, even though a promising method of treatment has been discovered, certain problems haven’t been overcome yet. The transplant of beta cells from the pancreas of someone who has just died-with as much tissue compatibility as possible-has had partial success. As with every other organ transplant, tissue rejection is a challenge. If the human genome project succeeds and the genetic code of the human body is thoroughly solved, it may be possible to cure diabetes by genetic engineering techniques. This is only at research level for now, but if scientists do their best, it is possible to find a way, since there is a treatment for every disease except for old age and death. You see Peter, as the vicegerents on earth, you humans are supposed to explore the secrets of the universe and appreciate the beauties you discover. I think I have said enough now. Thanks for listening, Peter!

Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir, Turkey.

Dear Peter, in order for you to understand me better, keep in mind a basic principle about the functioning of living organisms-they all depend on energy use. If no energy enters a living system, then no metabolic activity, no life function can be carried out. Think about a car without fuel. No matter how great the car is, it simply won’t work without any fuel in the tank. The human body is no different. Plants and animal products which people consume as food provide the body with fuel. However, you cannot make use of the energy in nutrients in the form in which you take them in. They need to undergo a process so that they become usable fuel for us, like crude oil being refined into gasoline to make a car work. This is roughly what my duty is. Without my functioning, you would be devoid of the energy to move a finger, and eventually die. Do you understand now how important a set of pipes I am? You just think that I look like a soft and hollow canal and misjudge me as simple. Well, I know that I don’t have such complex parts as the heart, lungs, and kidneys, but I’m created as a perfect work of art in plain design.

Although the hoses you use for watering your garden wear out and break in a relatively short time, my walls made of four layers keep functioning through a lifetime without any holes unless I contract a disease like cancer. My outer layer consists of a durable connective tissue, the next one consists of two sets-one horizontally and one vertically laid-of straight muscles, the next layer under that consists of glands spread in a soft connective tissue, and the innermost layer is the epithelial mucosa where the actual absorption takes place.

Now, let’s come to how I achieve digestion, one of your body’s vital activities. Actually, there is no place for me to take any pride in it; I’m just doing as I am ordered. Anyway, the complex processes occurring within my simple-looking walls are just fascinating! Every one of my cells producing the particular enzymes to break up each nutrient is like a separate factory. Some of these enzymes break proteins into different levels of peptides, some break the peptides into amino acids, some break fats into fat acids and glycerin, whereas some break carbohydrates down into glucose. All of these particular enzymes have their sub-branches within themselves. For example the enzymes breaking down fructose (fruit sugar), lactose (milk sugar), and starch are all different. In order for the enzymes to be effective, my inside needs to have the right pH level; the enzymes work in very sensitive conditions. To give you an idea, the enzymes in the stomach-which happens to be the second station the nutrients are destined for before they come to me-work in an acidic environment (pH: 2.5–3). In my case however, basic fluids are secreted and this strong acidity is neutralized for my enzymes to work.

My overall length is around 8.5 meters from the first entrance at the stomach to the last exit. The small intestine is nearly 7 meters long and the remaining 1.5-meter section is the large intestine. Although the small intestine is the longest section of the digestive tract, it is still called small since it is smaller in diameter than the large intestine.

The small intestine is also divided into three sections. The very short (25–30cm) and relatively thicker part right after the stomach is the duodenum. Bile-which works like detergent and facilitates breaking up fats-produced by the liver and digestive enzymes from the pancreas enter the duodenum. Thus, the nutrients are digested one step further and pass on to the second section (jejunum) and then to the third (ileum). You cannot easily tell apart these final two sections. As blood circulation is more intense in the second section, this section is more reddish and the contractions here are faster and stronger. The third section is narrower and has thinner walls. The blood circulation here is relatively lower and the movements are more limited. The thin membrane of connective tissue (mesentery) around me which attaches me to the abdomen wall and prevents me from knotting up is relatively fatty in this third section.

My most vital parts are the villi-tiny nipples covering the curly surface of my inner wall like a carpet. Shaped like the fingers of a glove, villi yield an enormously large inner surface. They contain a net of capillaries and lymph canals. In addition to the glands secreting the enzymes to break down nutrients, the secretion of certain glands protects me against the destructive effect of the stomach acid. Some cells secrete mucus for lubrication and protection of the passing nutrients. As some cells of the villi secrete digestive enzymes, some of my cells absorb the nutrients broken down until the final phase and pass them to the bloodstream.

Peter, how can some guys mistake such a splendid mechanism as a work of unconscious nature? What I’m telling you about is a manifestation of such great knowledge and might that it leaves you spellbound. I know the characteristics of foods, I know about the other organs’ needs, I adjust various enzymes and an absorption system, I fit them in a limited space… In addition, I do all these in the most ideal way, without any waste or flaw! C’mon Peter, can all these happen by themselves? Now, if I were to start telling everyone about the absorption mechanism in detail, they would probably see those cells as divine beings! The One who assigned special carrier molecules and a system for every nutrient molecule, has placed two transfer systems as blood and lymph pathways in every single one of those millions of villi! The blood pathway passes amino acids, water and salts into the blood directly, whereas the lymphatic pathway absorbs fats to pass them to the blood indirectly. After absorption, the nutrients become a property of the body and they are carried in the bloodstream to all the cells waiting for them in need.

Well, what about the waste then? Since everything you eat is not beneficial and usable, and some things are even toxic, they should be disposed of as soon as possible. The unabsorbed remnants are still too watery to be disposed of; sending them away as they are will be a waste of water and minerals. But don’t worry, everything is perfectly planned! Now the large intestine comes on duty. In this 1.5-meter section, the water of the waste and certain minerals are absorbed, and the waste solidifies. The large intestine is also divided into three sub-sections. The pouch connected to the junction of the small and large intestines is named the cecum and there’s the appendix at its end. This end sometimes festers and you have to have it removed in an appendectomy. Now, there’s this made-up story that the appendix was once longer since your ancestors only ate plants, that it has evolved into a shorter form for I now eat more meat, so on and so forth… Bah! Nothing is created in vain, Peter. If it didn’t have a duty, it simply wouldn’t be created. Only after some time did it dawn on them, after researchers proved that it is so necessary, that as a lymphoid organ, rich in blood vessels, it produces antibodies to fight the germs which somehow make their way into me.

The rest of the large intestine is the colon and the rectum. The mucosa covering my inner surface is rather smooth. It secretes mucus to facilitate the removal of waste. In addition, useful bacteria are made to work in abundance in the large intestine for your needs. These bacteria synthesize the group B vitamins like B12, thiamin, and riboflavin, along with vitamin K. You see how all the processes are carried out so splendidly? If it weren’t for vitamin K, your blood would fail to coagulate, and the slightest injury to your blood vessels would kill you. Could you ever have imagined that what looks to you like a sewage canal could produce vitamins of vital significance? Your Creator has infinite wisdom.

Peter, now you may wonder how the acts of this organ which resembles a long hose are regulated, how the nutrients inside are propelled, and then thrown out. To put it briefly, the “willful” part of your brain does not even know about it. Indeed, if it knew, it would be constantly busy with me and unable to do anything else.

Under the control of the autonomous nervous system, the straight muscles of my walls gradually contract in waves-this is squeezing act is called peristalsis. The nerve fibers connected to me fall into two basic categories-sympathetic and parasympathetic. As the sympathetic fibers pressure me to slow down, parasympathetic fibers stimulate me to act. Thus, I try to keep a balanced functioning between these two opposite effects. When the waste material I propel this way assumes a state to be disposed of, it reaches the rectum, and when the walls here strain, I make a natural call to you that I need to get rid of garbage. This is the step where your will has a partial interference.

Colon cancer, which troubles many people today, appears in this final section. The major reason is consuming too much meat and fatty foods, lack of movement, and leading a stressful life. When these are combined, I fail to function properly. If you want to help me at that, you should consume fiber-rich foods such as fruit and vegetables, and also lead a peaceful life. My web of nerves is amazingly rich and complex. Therefore, I am sensitive to nervous changes. If you feel down or sad, and if you suffer too much stress, I begin to go into spasms. Then I fail to dispose of waste, the toxic material inside me begins to damage my inner walls and eventually increases your cancer risk. Therefore, you’d better take up the habit of a glass of warm water when you get up in the morning, and try to have regular meals at the same times of the day. Most importantly, always have fresh green vegetables on your table, reduce meat intake… and it would be great if you could afford to consume olive oil rather than any other.

Hey, wait! I was about to forget the most important point. If you don’t have any peace of mind, all of these will be useless. This doesn’t mean that you will never worry; after all, this world is a testing ground and you are a human being like anyone else. However, if you give in to troubles and get overcome by feelings like panic, fatigue, and hopelessness, then my functioning will be upset. So, troubles faced with active patience and effort without giving up hope do not harm me much.

Peter, I do not wish you to wait until you see colon cancer patients disposing of waste through a hole in their belly into a plastic bag before you feel grateful for the blessings you enjoy. Actually, maybe I have told you at most a tenth of what I know about myself. Anyway, I think even this much will give you an idea of what a work of art I am. Thanks for listening to me, Peter!

Irfan Yilmaz is a professor of biology at Dokuz Eylül University, Izmir, Turkey.

I am placed inside your chest cavity as two air sacks-or bellows-surrounded by your muscles. I took my first breath right after birth and I still keep working non-stop. Even while you are sleeping, I fulfill my function with the automatic command I receive from the respiratory center at the back of your brain. My close friend Heart started working even before me while you were in the womb. I was resting then; actually I hadn’t even formed fully. As all your needs like food and oxygen were met in the body of your mother-whose heart you occasionally break-I didn’t have to make extra effort to get air, being filled and emptied. Even if I had attempted to do so, I would have had no chance of succeeding; since you were contained in the amniotic fluid, an attempt to breathe could have caused you to drown.

The first breath I take after birth is critical and rather difficult, since the windpipe is still much narrower than normal. On the other hand, the number of my alveoli where oxygen exchange with the capillaries is realized is so high in relation to body size that it balances the situation. When I make my first move and fill with air, I put pressure on the arteries and veins. Then the vessel directly connecting my artery to my mother’s aorta is dismissed, the curtain between the valves is closed and the blood circulations are separated. If this curtain is not properly closed and a gap remains in between, the oxygen-rich blood and the used-up blood mix and result in the disease known as cyanosis-or “blue baby” syndrome. As these two kinds of blood mix, the tissues are not supplied with sufficient oxygen and the white parts of the skin and eyes assume a bluish appearance.

Turning blue-purple due to lack of oxygen in the tissues is the same for smokers. Cigarettes-my archenemy-contain hundreds of toxic substances, such as carbon monoxide, which combine with the hemoglobin in blood and prevent oxygen transfer. Therefore, the lips of smokers turn slightly purple. You need to be careful with the air you inhale. The windpipe which brings air into me is covered with a ciliated epithelial tissue which catches the dust brought along and sweeps it outside. While you are asleep, the vibrating cilia of this sweeper work throughout the night and in the morning you get rid of the outcome of their propulsion by clearing your throat. However, every draw of a smoker kills 800–1,000 of our ciliated epithelial cells. After some time, they become unable to sweep the toxins (carbon, sulfur, lead, etc) inhaled with the air. I can’t stand it anymore! The increased air pollution is already putting enough strain on us… this habit is just too much for a lung to handle! It is just… an open invitation for cancer! Sorry, Peter, I didn’t mean to be rude. I appreciate that you don’t smoke, but I wish those who do would realize how splendid a mechanism they are destroying.

Now let me tell you about what a work of art I am. As you also know, art in a structure becomes more meaningful with functionality. As is the case with my other friends with which I work in your body, I am perfectly made to fulfill my duty. In other words, never mind forming an organ like me as a consequence of molecules and cells accidentally coming together, even a single protein molecule in my structure does not come to existence through unconscious causes.

With every breath you take, the pressure of the oxygen within the air inhaled rises, so it passes through my membranes by diffusion and into the adjacent capillaries; there it combines with hemoglobin molecules. At the same time, the carbon dioxide passes through the same membranes into me, and I dispose of it. Both of these are easier said than done! You breathe 13–14 times a minute and the whole thing is repeated over and over. As I keep expanding and contracting during breathing, which you are unaware of most of the time, first of all I need to be very flexible. Together with this flexibility, my most important quality is having the largest possible surface area within the smallest volume. My surface area of around 100m2 (as large as a tennis court) is made to fit into your chest cavity in the form of thin membranes so that my large surface allows gas diffusion. These membranes need to be kept wet; a special fluid is secreted as a precaution and respiration is realized smoothly. Without this fluid, my membranes would just stick together, unable to carry out their duty.

You can compare the course of the air inhaled to that of a car passing from a highway onto increasingly smaller roads and in the end reaching a dead end in the small sacks named alveoli. The air coming in through the mouth and nose unites at the expressway named the trachea, or the windpipe, which is 15cm long and 2–3cm in diameter. Incidentally, I have a couple of things to tell you about the way you breathe. As a matter of fact, inhaling is the duty of the nose. I’m sure it also has a lot to say as well, but let me just mention a simple fact about it. Now, you should inhale through your nose, so that the air you take in gets warm, wet, and is cleaned from dust. If you try to breathe this way, you do not trouble me much, and reduce the risk of catching a cold or an infection of upper respiratory system. Inhaling through the mouth helps dust and germs get into me and you might contract various illnesses from bronchitis to pneumonia. Now you know why kids who have adenoids who sleep with their mouth open get ill so easily. Sorry, I couldn’t help speaking on behalf on the nose.

Well, what were we talking about before that? Oh yes! The ways through which the inhaled air passes. As the name suggests, the windpipe which makes the air reach me is a cylindrical tube surrounded by 16–20 cartilaginous rings. As it is placed beside the esophagus, one side of the rings is made of soft cartilaginous tissue instead of hard, so that they don’t hinder swallowing. The muscular tissue near these rings helps them widen and narrow during respiration or coughing. I sometimes warn you by making you cough. Maybe it seems to be a disturbance, but if I don’t push out air by coughing through the contracted windpipe, contaminants can clog me up and cause you to suffocate. Therefore, the burst of air-what you call a cough-is a great blessing to you.

The sound system at the tip of the windpipe is another wonder. The used air I send out vibrates the cords in that voice-box and produces such melodies, gives voice to such speech! The air divides into the two lungs. My two sides are not symmetrical; the one on the right is divided into three, and the one on the left into two. I think this was meant to make room for the neighbor on the left, the heart. In addition, if there’s any cancer growth in me, the diseased part can be taken out by an operation and I can keep on functioning. God knows the wisdom behind this form. After that, these main bronchi separate into 8–10 thinner branches, like highways connecting to narrower roads. This branching resembles a tree turned upside down. At the tips of these thin branches are the respiratory bronchioles resembling clusters of grapes. The small spheres which make up the cluster are the end of the road and are the most vital parts. These spheres named alveoli are made of very thin membrane and they are surrounded by a net of capillaries (picture 5). These are the functional spots where gas exchange is realized.

I hang in the thorax with veins and arteries all around. There are two layers of protective membrane over me. One of them is stuck on me, whereas the other is stuck on the ribs which form the chest cavity. There is a fine and slippery fluid in between these two layers and it neutralizes the friction every time I inflate and deflate. If it hadn’t been placed there, I would wear out and be damaged. As I inflate during inhalation, the chest cavity should expand simultaneously to make space for me. If it weren’t given a flexible form, I would fail to breathe and you would eventually die. Fortunately, the protective set of ribs and their connection with the spine are flexible enough to make me work comfortably. In addition, the dome-shaped muscular partition (diaphragm) separating the thorax from the abdomen contracts and pushes down the organs in the abdomen. Thanks to the simultaneously programmed movement of both the ribs and the diaphragm I inflate with air and expand.

Being in constant contact with the outer environment makes me susceptible to various diseases. Coughing is among the foremost signals I give in the case of disease, and sometimes-excuse me-I produce a mixture of blood and phlegm. Also, I may have difficulty in breathing and warn you with chest pain. You should be alert to my signals. If bacteria and viruses infect me, they might reproduce inside my air sacs, and cause stiffening and suppuration.

I am particularly sensitive to allergic disorders. When the straight muscles on the walls of my bronchi contact an alien substance, pollens for instance, the consequent histamine secretion makes my muscles contract. In addition, allergic diseases, which can affect blood vessels, affect me a lot since I happen to be one of the major organs contributing to blood circulation. As a result of the contraction of my bronchial muscles and difficulty in disposing of the mucus I secrete to defend myself, I have trouble with breathing-you call it asthma.

In addition to this, we can mention diseases like emphysema, acute or chronic bronchitis as problems I frequently face. Even your anger has a great impact on me. Breathing becomes more difficult immediately.

Peter, I’m sorry, it is not possible to summarize a work of art like me within a few pages, but I need to stop now… but please, keep away from polluted areas and cigarette smoke! Send me as much fresh air as you can. And even though you mostly take me for granted, like my other teammates, please reflect upon what a blessing I am.

Irfan Yilmaz is a professor of biology at Dokuz Eylül University, Izmir, Turkey.

When you were a mere nineteen-day embryo, my creation began from a special mass of cells. At first, I looked like a tube, then I twisted, turned, and gradually the creation of my chambers and my neighboring veins began. Together with the other cells of the body, we developed to serve as different parts, such as nerves, skin, cartilage, muscles, and so on. And the cells which make me up are very specially programmed. When they reached a certain number and mass on your twenty-second day, they were commanded to march, and only God knows for how long. When all my cells contract together to beat, you feel it as your pulse. Though I operate in your body, Peter, you do not think much about my beats, but when you run fast, I just have to beat faster for your legs require more blood. Only then, Peter, do you notice me, but you do not give me a second thought anyway. You are so heedless, as if I will carry out this duty forever and will never get tired. Let us admit that is not so unusual for a young man, but the worst is you do not ever think of who blessed you with such a gift, and that really makes me sad. Nowadays you go to high school, and there they occasionally talk about me in biology lessons. Peter, you are not to blame, actually-teachers talk about me as if I were a simple pump. However, you cannot even move a finger if I do not pump blood into your brain. But today, I will let you know that I am not just a simple mass of flesh. I am going to tell you today that you should care about me both physically and spiritually, otherwise, you will truly regret it. I am just a friend, warning you about the bitter truth; you still have a chance to make it up.

All the cells, the building blocks of your body (maybe 100 trillion of them) need me for their nutrition, breathing, digestion, waste disposal, and to carry out their particular duties. You wonder why? Well, all their needs are met thanks to my being created to work ceaselessly. This is why I start working before any other organ at the embryonic stage. Even I do not know how long exactly I will work; sometimes, in spite of being in sound health, the appointed hour comes and I leave my duty obeying the divine command. For the most part, the Angel of Death does not tell me to stop for no reason-he somehow uses an apparent cause. There are so many causes to make me leave my duty, in such an age where accidents, bad habits, and suicides are tremendously high.

In fact, even I marvel at how I work. I am equipped with certain precautions against blood losses which occur as a result of injuries, but if the blood loss is not made up for and the bleeding is not stopped, I may get tired and stop functioning after a certain time. I can be easily affected by certain types of poisoning. This does not matter much, but what really upsets me is your living irregularly, unhealthy eating habits, inactivity, laziness, and especially your leading a stressful life quarrelling with everyone. I endure these for a while, but sometimes when I cannot take it anymore, I just quit or pretend to quit in order to draw your attention. Right after that, you have people screaming, calling the doctor in panic, demanding pills, adrenalin or heart massage… All of these are fine my dear, but why on earth do you wait until I become like that! Listen, Peter, I am telling you again, it is you who does me the greatest harm. So do not be offended if I one day get tired and quit! You just keep gulping down fatty foods, my downstairs neighbor, the stomach, keeps complaining that you are filling it up too much. When it is filled up, it starts putting pressure on me naturally. Haven’t you heard about the hadith counseling people to leave one third of their stomach empty and rise from the table before they are full? I can understand the vegetables, but what about the fast food, fried things, and other unhealthy stuff you eat? Be careful, you will have to pay for it before long, and it will be too late. Well, one has the right to benefit from the blessings in this world, but one should know where to stop. If you go on like that, my valves will be disabled by fat and my main arteries will be clogged. As for my coronary arteries, they are already created narrow and they can be clogged in a short time and lead to a heart failure.

You are just a couch potato lying before the TV all day without moving at all. I would not be surprised if you started going to the corner shop by car. If only you did exercise for a little part of the day. Some of your friends do the daily prayers and kill two birds with one stone. They fulfill their duty to their Creator and relieve their hearts with the bodily exercise. In addition, their hearts are at ease thanks to their faith. Another welcome relief for us is their fasting for a whole month once a year. Staying hungry for a certain part of the day comforts me and gives me a chance to burn some fats.

The muscle tissue which makes up my main structure is designed as an intricate ball of fibers and so I am able to function properly without changing my shape too much as I contract and relax. The surface of my walls is wrapped up in a double layer in order to prevent harm from rubbing against the ribs, which are set around me as a protective cage. Also, there is a special liquid between the two layers of the membrane and this lowers the friction even further. C’mon Peter! Who can arrange so many precautions so splendidly?

Like car engines with four cylinders, I also work like a pump with four chambers. My upper chambers are called atriums. The one on the right takes in the waste-rich venous blood, and the one on the left takes in the oxygen-rich arterial blood. The muscular strength of these chambers is relatively low, but it is good enough to pass the blood they take to the lower chambers. As for my lower chambers, named ventricles, they have thicker walls and stronger muscles. They are given the ability to contract and pump blood with great pressure. Moreover, the lower chamber on the left has even stronger muscles and thicker walls since this very chamber enables me to send blood to the entire body with great pressure and speed. Thanks to the large vein named the aorta, I send blood to each organ in the required amount and at the right speed. Precise timing is vital for my four chambers to contract successively, to open of the valves at the exact moment they should, and to send blood to the neighboring chamber or to the two main arteries. The closing of the valves also requires perfect timing to prevent the blood from flowing back. The coordination of this timing mechanism is obtained through the regular production of electricity by the atrioventricular bundle. If there is something wrong with the timing of my valves, or if they cannot close properly because they are blocked with fat or calcification and so let blood leak, you diagnose this situation as a disease. As a precaution against blood flowing backwards through the valves between the atriums and ventricles under heavy pressure, some cords are tightly fixed under them. You are not aware of any of these, but I keep working even when you are asleep. Naturally, I may change my speed at different times, according to what you do. While you are asleep, I work at an easier tempo. I work faster than normal while you are running or doing heavy exercise and I send the necessary amount of blood to every organ. My energy source? Well, the fuels I mostly make use of are fatty acids, lactic acid, and sugars. In addition, thanks to my special metabolism, I never get tired. There is only a very short period of rest of one tenth of a second between every contraction and relaxation I make. The stimulating command must come with perfect precision so that all my muscles start to contract and relax simultaneously and so that I can generate an efficient pumping force. Actually, I am not quite sure how this timing is arranged during different activities. A tiny automatic center on me produces electrical signals; the activities of upsetting and then resetting the ion balance inside and outside the cells in order to produce these signals is carried out with reactions happening in a time as short as one thousandth of a second. Even though these cells make me work with the electricity they produce, I am not really independent. The foremost among the factors that affects my functioning is the nerves from the brain. Therefore, the fear, anger, and sadness you experience upset my functioning as well. This must be why people have taken me as the center of emotions; although anger and sadness take place in the brain, I was located as the emotional center, as the effect surfaced in me.

Peter, I will ask you a simple question: is there some engineer who made the TV set you lie before? Are there people who write the articles in the magazine you are holding or who lay out the letters and pictures? There are some agents right? So, more perfectly than all of these, should there not be One who has created me and my system of blood vessels, and then placed me in your chest cavity? Well, it is high time you switched off that TV set. Now Peter, just as I fulfill my duty regularly to keep you alive, you should also spare just ten minutes to pray for and praise your Lord Who has created your body so perfectly. In the meantime, I will have found a chance to get rid of the strain you put me under because of your hurry and stress.

Within these few pages, I have probably told you only a thousandth of my splendid structure and the precision of my functioning. Neither I, nor physicians have the proper knowledge to explain all about me completely. So, my friend Peter, you need to learn to say, “How beautifully it has been made,” instead of “How beautiful it is.”