The thymus may possibly also be described as an amazing shrinking gland. It is made up of two lobes that are joined together by means of a connective tissue. The thymus is present inside the chest, just behind the breastbone and on top of the heart. Even in a newborn, the thymus is somewhat large and its growth continues all through the childhood. The weight of the thymus is the most immediately before an individual attains adolescence and during this time its weight is about 1.5 ounce. Nevertheless, the thymus starts shrinking from puberty onwards. In adults, this organ is so small that it may be difficult to locate it during an examination of the chest.
In spite of being small in size, the thymus has an important function in sustaining a healthy body and mind. In the absence of this organ, it would be impossible for our immune system to function normally and this, in turn, would severely impair the ability of our body to combat infections. Whenever any bacteria, virus or any other alien body invades us, it is essential that our body is able to identify these trespassers instantly. Our immune system possesses the incredible aptitude to differentiate between the cells of our body as well as those that invade us. When the immune system identifies these invading cells, it should work to eliminate them before they start reproducing and take control. The cells that make up immune system and work to combat the alien bodies are known as leukocytes or white blood cells. These white blood cells overcome the invading organisms or substances; transmit messages regarding the invasion by the foreign bodies and call for immediate additional fortifications. In such cases, the thymus has a vital role in attacking the invaders, as it produces a variety of white blood cells called the T cells or T lymphocyte.
It may be noted that all the times several million T cells circulate inside our body, always prepared to counteract any attack by a foreign body. Since one's birth, all of us possess an assortment of T cells. These cells facilitate immune system in fighting several ailments, for instance, measles and also the several thousand pathogens that develop every year. The receptors on the cells walls of the T cells trigger them to combat the pathogens. While these cells are circulating in our body, they get in touch with different white cells that get enmeshed inside the invading cells or harmful foreign bodies.
The T cells take action in numerous different ways. Whenever there is an attack by foreign bodies, the T cells act by starting to divide as well as multiply them as a strategic ploy to form clones of themselves. As a result of such cloning, four types of T cells come into existence - killer T cells which assault as well as obliterate the invading cells; helper T cells that summon additional fortifications; memory T cells which begin an instantaneous attack in case the invader cells attacked and destroyed by the killer T cells make a reappearance; and the suppressor T cells which call off the forces after the battle is tamed.
When the helper T cells call for reinforcements, one more type of white cells joins the battle against the foreign bodies. They are called B cells or B lymphocytes, a number of which turns into plasma cells when activated. The B cells produce the entire types of antibodies manufactured by our body to combat diseases and infections. Antibodies search for and subsequently deal with the invading cells, making it easier for several different types of killer cells circulating in our body to attack and eliminate them.
T cell production as well as triggering of the B cells is, to a great extent, regulated by the hormones produced in the thymus. Thus far, scientists have been able to identify four dissimilar hormones produced by the thymus - thymosin, thymic factor (TF), thymic humoral factor (THF) plus thymopoietin. Not much is known about the attributes and actions of these hormones and further researches are necessary for this purpose.
In 1981, the Centers for Disease Control had officially recognized AIDS (acquired immune deficiency syndrome), which is an acquired ailment attributed to the human immunodeficiency virus or HIV, to be an pandemic disease. This virus can only be transmitted from a patient to a healthy person by means of exchanging body fluids, primarily blood and semen. In fact, an individual may be infected by HIV for several years, but the symptoms of AIDS may develop much later. Ever since 1981, more than 700,000 people in the United States have been found to be suffering from AIDS and as many as 400,000 patients have already succumbed to this condition so far. It may be noted here that when a person develops AIDS, the condition destroys his/ her immune system cells, especially the T cells. Besides devastating the cells, AIDS can even stop the healthy cells of the body from functioning normally.
Scientists who have undertaken research on AIDS have also studied thymosin. In fact, they are experimenting to find out whether this hormone possesses the ability to mend the impaired immune system. As it has been found that several children who were born devoid of the thymus glands showed amazing reverse immune deficiencies when thymosin was administered to them, the scientists are hopeful that increasing thymosin supplies may help to augment the production of T cells as well as B cells in patients suffering from AIDS and also heighten the actions of these cells in combating the virus that is responsible for this condition.
For several centuries now, scientists have been puzzled by the minute, profoundly hidden pineal gland. In his writings, Rene Descartes, the renowned 17th century French thinker, described the pineal gland as the 'seat of the rational (balanced) soul'. Nearly all mammals, reptiles, birds and fish possess the pineal glands and this has been true since ages. Paleontologists (people who examine prehistoric fossils) have discovered proof that the pineal glands have been in existence for at least 500 million years. While the precise role of the pineal glands still continues to be a mystery to the scientists, the fact that these glands have been there for such a long time itself indicates that they are definitely vital for the survival of the humans.
However, the scientists are certainly aware of some aspects of this gland. In humans, the size of the pineal gland is usually below one-fourth inch and its weight is just about one gram. It has a conical form or, precisely speaking, is pinecone shaped. It is interesting to note that the gland derives its name from its pinecone shape. The pineal gland is found just near the center of our brain. This gland starts calcifying when one reaches puberty and this results in the accumulation of calcium, which is referred to as brain sand. However, apparently there is no reason to be concerned, as this kind of incomplete calcification does not have any affect whatsoever on the brain's functioning.
It is believed that the pineal gland is the only gland in our body that makes the hormone called melatonin. In the case of humans, this hormone is release all through the night and it appears that the release of melatonin has a direct relation with darkness or absence of light. Light goes into our eyes during the day time and it transmits some signals or pointers to our spinal cord by means of the optic nerve. Subsequently, these indicators are transported to the pineal gland by means of the nerve impulses. The production of melatonin is stopped till the pineal gland receives these signals. However, all through the day, the pineal gland readies for its work during the evening by producing serotonin from amino acids. In turn, serotonin changes to melatonin during the night.
In 1958, scientists at the School of Medicine of Yale University discovered melatonin for the first time. Similar to the majority of the work undertaken with the pineal gland, the work of these scientists was founded on studies conducted on animals. Apparently, the levels of melatonin directly regulate the reproduction habits of nearly all animal species. Those having a prolonged gestation period, for instance, the bears and deer, usually conceive during the fall and reproduce during the spring. However, it has been found that animals that have a brief gestation period, for instance, birds and rabbits, give birth sometime during the summer or spring. This especially ensures that the newborns are provided with the optimal opportunities to survive. The production of melatonin reaches its peak during the dark and cruel winter months, while sexual activity is at its lowest.
In the case of humans, enhanced melatonin levels is related to an augmented feeling of drowsiness, a desire for foods rich in carbohydrates and also lack of ability to remain focused. It has been found that people living in places where the winters are prolonged and dark usually suffer from a condition commonly referred to as seasonal depression. It is possible that some of you may have experienced what is called 'winter blues'. When you experience this condition, normally you have a feeling of depression, and are possibly also weary and introverted during the winter. In addition, you also have a propensity to gain weight during this season. In case you experience all the symptoms mentioned above, you might possibly be a victim of seasonal affective disorder (SAD).
It is believed that only in the United States more than 30 million people are affected by this mental problem. Majority of such mental disorders are found in the north-eastern region, in states like Alaska and Washington as well as the region around the Great Lake. In a number of instances, the symptoms of SAD may turn out to be very serious. People suffering from this problem lose their ability to deal with even a minor problem in their live and seldom remain awake during the day time.
In general, people suffering from SAD feel much better with the arrival of spring and spending a vacation in regions having more sunny climates may possibly aid in alleviating their symptoms.
As a result of these findings, scientists have now started trying out light therapy. They have discovered that when people suffering from SAD are exposed to bright light for some hours daily it may help to cure their gloominess as well as their intense desire for carbohydrate rich foods. It is interesting to note that when applying this light therapy for only two to three days it has shown noticeable positive results in SAD patients. However, it is important to ensure that the light that these patients are exposed to ought to be no less than 10 times more bright compared to that of a normal room that is lit brightly.