Issue 75 / May - June 2010
It's me Peter, your Endocrine System!
We are now approaching the end of the series of organs that told you about themselves. They have been pointing out the seal of God on them, and celebrating themselves as they manifest the beauties and the delicacies of God‚Äôs art. Thus, they have not only expanded your knowledge, but also guided people to the truth of God‚Äôs Oneness, stressing that natural and biological causes alone can never be an explanation for their splendid creation.
Each of your organs told you about its perfect structure and how it functioned within your body system. Let us think that each organ is a musical instrument. No matter how splendid and artful a musical instrument is, its true value is understood only among other orchestra instruments as they perform a wonderful concert. Your body is like that orchestra, where hundreds of instruments play together. In addition to the perfect structure of each organ, more importantly all the organs have to work together perfectly as a team. The success of an orchestra depends on how the instruments play in harmony with each other. The conductor of an orchestra is the person who ensures that harmony. The orchestra members carefully watch the conductor and play according to his arm movements, sometimes louder or softer, sometimes pausing or breaking into a very loud introduction. That is how a perfect concert can be performed.
In order to achieve such harmony, the organs in your body need a system that works just like a good orchestra conductor. This ‚Äúregulating system,‚ÄĚ which has to maintain the perfect harmony and order of the ongoing activities in your body, has two sub-units: One is the brain and the nervous system, and the other is me; your endocrine system (hormonal system). Since I work as a system that consists of many organs, from now on I will refer to myself as ‚Äúus.‚ÄĚ Each of us adjusts itself to the whole system by carefully watching the movements and works of the other organs. At our head are the brain and nervous system, which act as the general control center. However, it cannot carry out the regulating and controlling task alone; it needs our help.
The most basic principle that your body has to follow in order to maintain its health is keeping the inner medium stable in a dynamic balance while responding to varying environmental conditions properly. This is also known as homeostasis. For the inner medium to be kept stable, it is first of all important to be aware of the changes that are happening in the outer world, which is initially done by your sense organs. The signals related to the changes in the outer world are sent to your brain and nervous system through the sense organs. Afterwards, the signals are evaluated, and then they are sent to the related organ so that the proper reaction is produced and the inner balance can be regained. While all the activities regarding growth and reproduction are carried out, the inner medium should be kept stable at the same time (homeostasis). In order for all these activities to be performed continuously, you need inner secretion glands, which are small, but highly important.
The most important of all your organs that constitute the endocrine system is called the Pituitary (hypophysis) gland, which is recognized as the commander of all these organs and situated in your brain. The other secretion glands included in my system are the thyroid, parathyroid, suprarenal (adrenal) gland, epiphysis, pancreas, testicles, and ovarium. Now, these small but very important organs of mine will respectively talk about themselves and demonstrate the perfect program and the sensitive balance within which they work. You are the one who will draw the necessary lessons from this.
In all tissues, there are specific recipient molecule groups that respond to a particular hormone. Each hormone is programmed to stimulate its target cells, which contain those special recipient molecule groups that start doing their specific work. The principal functions of my endocrine system are: to enable growing; to regulate the necessary reproduction process in an ordered manner; and to carry out the physiological processes in the body in a relatively stable medium. I guess your amazement, admiration, love, and apprehension will increase when you hear about my secretion glands. Now, here comes the hypophysis.
My name is Hypophysis (the Pituary Gland)!
I am appointed as the commander of all your glands. Therefore, I am situated in a very firm place at the lower brain. I am an organ that is as small as a bean and that weighs only a few grams, but I have got so many talents. I have two parts. The first is my frontal lobe (adenohypophysis) which secretes most of the hormones. Our Creator has given key roles to the hormones of my frontal lobe to direct secretion activities of other endocrine glands. For example, thyrotropin hormone is arranged in such a way that it affects the thyroid gland and stimulates it for secretion. The unbalance in my thyrotrophic secretion affects the function of Thyroid gland negatively. If it is secreted too much, hyperthyroid; if it is secreted too little, hypothyroid illnesses emerge. In both cases, some problems occur during metabolism. Adrenocorticotropic hormone is created to arrange the activities at the adrenal cortex. Follicular stimulating hormone has two very important roles. The first one is regulating the secretion of estrogen, which is one of the female hormones. The second one is maintaining the physiological activities in the maturation of sperm cells in males, as well as the egg cells in females, for the continuation of human generation. The Luteinizing hormone together with the Estrogen stimulates the secretion of other sexual hormones (progesterone and testosterone).
When you were born, you were 20 inches tall. Now you are almost 6 ft tall. Both your height and your hands and feet grew. Meanwhile, your head and body got bigger proportionally. Another important secretion of yours that controls your growth appropriate to your age is somatotropin hormone. If, for some reason, my working balance got deteriorated, and this hormone secreted less, you would be like a dwarf, or some of your parts would be unbalanced with your body and abnormally short. If this hormone were secreted too much, then you would get into gigantism due to abnormally large growth. Together with gigantism illness, several problems occur; i.e., heart and blood pressure problems, muscle weaknesses, and problems regarding immunity and general metabolism.
Other hormones that are secreted from my frontal lobe are prolactin hormones, which help milk glands develop in expecting mothers, and melanocyte stimulating hormone, which stimulates the pigment cells that give color to your skin. However, these two hormones have no relation with the other hormonal glands.
The lipoprotein molecule of my melanocyte stimulating hormone helps the morphine substances, known as encephalin and endorphin, to be synthesized. You can call these two substances naturally inherent drugs. These secreted substances help you to bear several physical pains. The secretion of my hormones has direct relation with your nervous system and psychological well-being.
Although formed in the hypothalamus part of the brain, one of the hormones that is secreted after being stored in my back lobe (Neurohipofiza) is oxytocin, and the other one an antidiuretic hormone called vasopressin. Oxytocin makes the smooth muscles work. In particular, it stimulates the contractions at uterus during labor and delivery, and it also stimulates the secretions of milk canals by making them contract. Vasopressin enables blood vessels to shrink, causes the blood pressure to increase, and also reduces the production of urine by increasing the transition of water to blood through the kidneys. Hence, it prevents dehydration in hot and dry weather. In the deficiency of the secretion of this hormone, an illness called diabetes insipidus will occur and water metabolism will be deteriorated. I have more amazing features to tell, but I should not be selfish. I think it is time for Thyroid to speak.
My name is Thyroid!
I am placed in your neck, right at the two sides of the trachea (air tube) and below the larynx (voice box). I consist of two pieces that are attached to each other with a thin tissue. Inside me, there are many little saccules called Follicules which are densely surrounded by a capillary network. Following their innate program my cells produce three important hormones in the cavities of those saccules. The two of them are thyroxine and triiodothyronine, which contain iodine atoms and the other one is calcitonin. My hormones have highly important impact in your body. Our Lord God has appointed me, the hormones secreted by a very small piece of flesh, with regulating the oxygen use of all of your cells, and thus the speed of your metabolism which all affect your body‚Äôs overall performance. In addition to that, I also adjust your cholesterol level by lowering it in your blood. My iodine-containing hormones are vital for children‚Äôs growth. In the case of their deficiency, conditions like growth failure, dwarfism and mental disorders appear. If there is not enough iodine in the earth or water, it becomes more difficult for me to produce hormone and I start to work harder, which causes me to enlarge. This is a disease called goiter. When I secrete excessive hormone, your eyeballs become bulged, a disease called exophtalmic goiter or Basedow syndrome.
My iodine hormones and the stimulating Thyrotropin hormones secreted by the Hypophysis work together; they watch and control each other. If I get lazy and slow down secretion, the Hypophysis immediately warns me. If I secrete too much, this time Hypophysis stops warning me and waits for me to ‚Äúcalm down.‚ÄĚ
Do you see what a wonderful system I am? Not only between us, but also all other systems have the same feedback organization between themselves and the Hypophysis. The Hypophysis is an organ as big as a chick pea, and we are only a small piece of flesh. Peter, look at the great jobs we are doing! Can coincidence play any role in this, do you think?
Lastly, I will tell a little about Calcitonin, a hormone which works to adjust the calcium level in the blood serum. That is not an easy job at all. This hormone is vital in the healthy growth of your bones; otherwise your bones will empty, get weak and they might even break for no reason at all.
My name is Parathyroid!
As my name suggests (‚Äúpara‚ÄĚ is a prefix signifying alongside of, beside), I am located just behind the Thyroid, consisting of four small parts. I have so many important functions beyond what is commonly known. My foremost duty is to delicately adjust the amount of calcium between your skeletal bones and your blood. Moreover, I am also assigned with controlling the phosphate and magnesium metabolism. In order to do that, I produce a hormone called parathormone. Of course, I have no idea about the chemical composition of this hormone; but I am just doing my job by producing it and working as I am programmed. When the level of phosphate in the urine and the level of calcium in the blood are measured, you can understand whether I am working well or not. The decrease of calcium in your blood leads to the stimulation of your nerves, thereby causing muscle spasms or titanic contractions that occur along with dotage. The healthy function of your heart and muscles highly depends on this calcium. Who knows, Peter, what other functions of me you human beings will discover in the future!
My name is Adrenal gland!
I consist of two little parts located on top of the kidneys, one on each side. Do not underestimate me by just looking at my size! You will be amazed to learn what crucial functions I perform. Each of my parts has an inner (medulla) and an outer (cortex) section. Those two sections differ quite markedly from each other in their structure, functions and in the origin of the embryonic layer where they form. But despite those differences, our God Almighty has put them one within the other. The two important hormones that my inner section secretes are Adrenaline and Noradrenaline. My adrenaline secretion speeds up the conversion of glycogen (in your liver) into glucose, and thus the sugar level increases in your blood depending upon your energy needs. This increases the power and the speed of your heart contractions and constricts the diameter of the blood vessels, thereby causing the blood pressure to increase. I assist in dilation of the narrow bronchioles of your lungs so that you can get more oxygen. When you become nervous, quarrel with somebody, face a danger or experience any stressful moment, I cause all those activities to happen by secreting more hormones expeditiously. That is how I help in protecting your body. All in all, 80% of my secretion is adrenalin, whereas the 20% is noradrenalin. Noradrenaline has less impact on your heart and metabolism.
My cortex (outer section), where steroid types of hormones are produced, secretes aldesterone, cortisol, and some androgens (a male hormone). Aldestrone regulates the water and salt levels (especially sodium and potassium metabolism) of your body. Cortisol meets your glucose needs if you are starving by breaking down the proteins into amino acids; it is also responsible for preventing the infections and allergies. Although the testicles (male reproductive glands) are the main organs that produce the male hormones, I also supply them. My androgens help in the development of male characteristics such as voice changes, beard and moustache growth and hair growth. When women get older, the androgens that I secrete causes the voice to deepen and hair to grow on their bodies.
My name is Epiphysis (Pineal gland)!
I am a small gland that is situated at the roof of the dieencephalon (‚Äúinterbrain‚ÄĚ). As it is most commonly known, I secrete the melatonin hormone. This hormone helps the melanin (the black or brownish pigment that gives your skin its color) to aggregate or dissolve in the special skin cells called melanophore. Thus, it senses the intensity of the light that changes according to the seasons and day length, and adjusts your skin color by lightening or darkening it. Moreover, I work as your biological clock, regulating your sleep-wake cycle. It is also thought that I arrange the different working periods of your organs.
Our Name is Testicles!
We are male reproductive glands. Our God Almighty has created us for the continuation of human generation. Each of us is oval-shaped and located in a pouch that weighs 25 grams and facing to each other. Each of us is protected by a case of skin and muscle. This case extends into our internal part where it is divided into 200-400 lobules. Each lobule consists of fine coiled tubes. The reproductive cells and the sperm cells which contain a group of your genetic program are produced in those tubes.
When you reach puberty, upon responding to the stimuli that comes from the hypophysis, we start to produce sperm, as well as Testosterone, a type of androgen (male) hormone. Testosterone is necessary for your male appearance; it helps in the developing the characteristics that distinguish you from females in terms of appearance.
A special cell division called meiosis is needed for sperm production. Along the layer that make up the walls of the coiled tubes lie the cells that are called Spermatogonium. Each of these contain 46 chromosomes (23 maternal and 23 paternal). As a result of serial divisions and crossover of those cells, new cells are created with new characteristics. From one Spermatogonium, four sperms are formed and each of them has 23 chromosomes.
Each sperm differs from one another, and each of them contains a mosaic composed of the different characteristics you possess. Among the millions of sperms that are produced, not one of them is identical to another. The reason is the interchange of sections between pairing homologous chromosomes (that you take from both your mother and your father) during the process of meiosis. For example, in one sperm, your nose traits that come from your father might come together with the ear traits that come from your mother. In another sperm, for example, the fingers traits that are inherited from your father might come together with the eye traits that are inherited from your mother. When so many different traits can be mixed in so many different ways, you can imagine the great potential of variety for human beings.
We are private organs that some people see as ‚Äúobscene‚ÄĚ to talk about and which generates ‚Äúdirty‚ÄĚ sperm-containing fluid. However, as you have seen, we are given to you as a gift from God, wrapped with so many beautiful meanings, one of which is the important task of continuing human generations.
My name is Ovarium!
Dear Peter! My duty is particularly relevant to women; I am the female reproductive organ. Therefore, I should begin by saying something like ‚ÄėI am Jenny‚Äôs‚Ä¶‚Äô this time. Just as the Testicles are the male reproductive system, the ovaries are the woman‚Äôs organ. It cooperates with the male productive system in order for human generation to continue. We, the two ovaries, are located in the lateral wall of Jenny‚Äôs pelvis, one on the left and one on the right, and we measure approximately 1x 0.60 x 0.60 inches and weigh between 4 and 8 grams. Even before Jenny was born, we contained an amazing 150‚Äď500 thousand immature egg cells inside us.
During childhood, the follicles which contain the eggs diminish continuously, and by the time a young girl reaches puberty, only 35,000 of these follicles remain in each of her ovaries. Throughout the woman‚Äôs reproduction lifespan, usually between the ages of 13‚Äď50 years, a mere 300‚Äď500 of these follicles actually transform into mature eggs. You will certainly realize that you have reached puberty when I begin to produce the estrogen and progesterone hormones. As the estrogen I produce stimulates the development of the female‚Äôs sexual characteristics, progesterone prepares the wall of the uterus, making it more receptive to the implantation of a fertilized egg. If the egg I produce is not fertilized by sperm, every month (in approx every 28 days), it will degenerate and then be discharged from the body together with the lining of the uterus during menstruation. Then another one of my eggs matures, and patiently begins to await sperm.
The principle event of chromosomal change in my eggs and their diminishment in numbers is the same in the development of sperms. The only difference being that every spermatogonium produces four sperms, whereas only one mature follicle is produced from the mother cell (Oogonium) that produces my eggs. The remaining three are degenerated. You would have thousands of eggs awaiting fertilization if this was not the case. However, due to the fact that your bodies are not capable of harboring and protecting so many eggs, our Creator provided you with the mechanism of reducing the number of these eggs, and therefore relieved you of any difficulties.
I must take this opportunity mention another two of my organs, one of which is the pancreas, who described itself previously (see The Fountain # 67). As you may recall, the pancreas is a compound gland. The pancreas previously described how it produces digestive enzymes, and also how it produces insulin and glucagon to deal with the metabolism of carbohydrates. As this is a very complex organ, we allocated the pancreas the opportunity to describe itself and explain its functions in a previous edition of the magazine. For more information you may refer to the issue listed above.
An organ which is a part of your immune system, and also considered part of the endocrine system, but an organ you are probably unfamiliar with, is the Thymus gland. If the immune and lymph systems feel the need to describe themselves to you in the future, the Thymus gland will inform you that it resides at the same level as your heart, behind your breastbone (sternum). Then it will go on to define its specific duties. But for the moment, the only thing I am going to inform you of is the most important duty of the Thymus gland.
The Thymus gland produces soldiers called T lymphocytes (T cells) and special antibodies which fight the invasion of diseases, illnesses, and also attack cancer cells and any foreign antigens. The Thymus gland is recognized as a part of the endocrine system because it produces hormones and antibodies. The special lymphocytes and antibodies that are produced in such a complex process by other organs of the immune system are transformed into T cells as they pass the Thymus gland. Then, gaining new characteristics, they secrete specific hormones which in turn stimulate the development and differentiation of T lymphocytes.
Whatever the system may be, the Thymus gland, to the contrary of other organs, is at its largest and most active during the embryonic and neonatal periods. During adolescence, the Thymus gland begins to shrivel and shrink, and continue to shrink gradually into old age. The reason why the Thymus gland is large during the early stages of life is because it must constantly generate new antibodies to enable the body to fight against new germs and diseases, which the body encounters every day.
I may have extended the topic slightly this time because every organ of my endocrine system described themselves individually, and then we got onto the subject of Jenny‚Äôs special case, as wel as the different aspects of Peter‚Äôs case. All the organs I mentioned today are small, but as you may have noticed, these small organs behold great mystery and wisdom. In addition to this, all of these organs‚Äô individual duties are connected, in particular the Pituitary gland (Hypophysis), and have been arranged and regulated in such a way that they control one another. Can such a magnificent hormone system and bodily activity working in such harmony be explained as a mere coincidence?
Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir, Turkey.