The Adrenal Glands
As adrenal is a Latin term, experts in this language would easily find where the adrenal glands are located. Nevertheless, a translation of the term would also make it as easy for others to find these glands. The word adrenal has been derived from two Latin expressions, ‘ad’ denoting ‘near’ or ‘toward’ and ‘ren’ referring to ‘kidney’. There are two adrenal glands in our body, each positioned on top of one kidney and its shape is somewhat akin to a triangular ski hat. Each adrenal gland comprises of two parts that make their individual and distinct products. Each of these two parts also functions independently without having anything to do with the other part.
On average, the weight of an adrenal gland is about five grams (approximately 1/4 ounce). Its length is below two inches, while the width of an adrenal gland is roughly one inch. Approximately 80 per cent of the adrenal gland is made up of a yellow-hued external section known as the cortex. The inside part of the gland is known as the medulla. Similar to the thyroid gland, the medulla is totally packed with blood vessels that impart a dark red color to it.
The adrenal cortex
Among the entire glands present in the human body, the adrenal cortex is of most importance. In fact, the human body would have passed away if it did not possess the aptitude to adjust itself to the continuous changes. More importantly, the minimal alteration or strain would have turned out to be fatal in the absence of the hormones secreted by the adrenal cortex.
The pituitary glands regulate the adrenal cortex’s subtle operations by means of controlling the secretion of a poly peptide hormone called ACTH (adrenocorticotropic hormone). On its own, the adrenal cortex produces a whopping 30 dissimilar hormones. These hormones can be classified under three groups depending on the similarity of the steroid as well as the structure. It may be noted that all the steroids have their origin in the same cholesterol. While advocators of a ‘healthy heart’ have disrepute cholesterol, in effect, the presence of rational amounts of cholesterol is vital for producing corticosteroids - the steroids manufactured by the adrenal cortex.
It is worth mentioning here that the adrenal cortex is made up of three zones or specialized strata. From the most external to the inner most layer, these zones are known as the zona glomerulosa, zona fasciculata as well as zona reticularis, in that order. We shall now divide the discussion to describe the structure and functioning of all the zones mentioned above.
The main hormone secreted by zone glomerulosa or the outermost layer of the adrenal cortex is called aldosterone. The intensity of this hormone in our bloodstream has a direct influence on how our kidneys function. As the levels of aldosterone increases, our body holds back salt, while excreting potassium. When there is an excessive of salt (sodium) in our body, it leads to fluid retention. On the other hand, an individual may experience hypertension (high blood pressure) if the aldosterone levels remain high for a prolonged period. However, we are fortunate that our body many fool-proof techniques to neutralize this effect. In case there is an excessive build-up of sodium in the body, the kidneys receive chemical signals instructing them not to reabsorb the sodium circulating in the system. Subsequently, the surplus sodium is excreted through urine.
This is zona fasciculata or the middle layer of the adrenal cortex, which produces an excellent healing hormone called cortisol. The magic drug cortisone is prepared from this hormone. In fact, one may reminiscence the amazing healing properties of cortisone when they are exposed to any food or medicine causing large reddish swellings on their skin or they fall victim to the poison oak, which seem to close up their throat and make breathing extremely difficult. Administering this steroid in the form of an injection will provide immediate relief from acute allergic reaction. In addition, cortisone is extensively used in the form of a pill to treat numerous grave ailments, including rheumatoid arthritis, bronchial asthma and even ulcerative colitis. This steroid is also available in cream form and is used to heal an assortment of skin disorders.
Under normal circumstances, our body secretes approximately 20 mg (2/3 ounce) of cortisol daily. This amount is almost 200 times more than the amount of aldosterone produced by the body. Cortisol works to control the secretion of ACTH (adrenocorticotropic hormone), normalize the levels of fluids in our body, sustain a normal blood pressure, instructs the body to metabolize glucose and protein, augments or reduces the body fat and also has an influence on our immune system. When our body is under extremely stressful conditions, at once the adrenal glands start thrusting cortisol into our body. In fact, at its peak the adrenal glands can produce 20 times more cortisol than what is produces under normal circumstances. As the production of cortisol increases and it is pumped into our body, additional energy is supplied on an emergent basis. Literally speaking, cortisol cannibalizes fat from the tissues and amino acids from the muscles. At the same time, the pace of metabolism becomes rapid, while the immune system retreats. This makes it possible to have loads of energy at our body’s disposal.
Such changes are extremely useful when an individual is struggling with a grave internal damage or confronting a particular bodily danger from the external world. Nevertheless, cortisol production may go up abnormally due to the emotional stress in our everyday life in modern times. What is concerning is that when any individual constantly remains in an alert condition, it may result in the development of severe disorders related to stress.
Extremely elevated cortisol levels in the body may also result in a health condition called Cushing’s syndrome. Often, this is an accidental outcome of using cortisol to treat a health condition. A person may also suffer from Cushing syndrome owing to the malfunctioning of the pituitary gland, which may be manufacturing excessive adrenocorticotropic hormone or ACTH. This may occur frequently. Growth of pituitary tumours is said to be another cause for excessive cortisol production. In many cases, surgery may be necessary to remove the pituitary tumours.
People suffering from Cushing’s syndrome usually show a variety of symptoms that are visible. One of commonest symptoms is obesity. Frequently, the face of the patient looks roundish as they become extremely fat. Even the body’s trunk becomes weighty and the surplus fat formed on the trunk is often known as ‘buffalo hump’. The bones of the patient become extremely feeble and frequently they experience back problems that put out of action. When one has Cushing’s syndrome, he/ she may also have an elevated glucose level in their bloodstream and this may eventually result in diabetes. Hypertension or high blood pressure is also a common symptom of Cushing’s syndrome, in addition to debility of the muscles and a tendency to suffer bruises. The acuteness of these symptoms of Cushing’s syndrome makes it apparent that it is necessary for our medical professionals to keep an eye on people being treated with cortisol for a long time. Besides, it is also important that all treatments with this steroid must be done with great caution.
At the same time, it is also crucial for people receiving treatments with cortisol or other such medications not to continue them for a prolonged period and gradually try to stop taking these medicines. While they are undergoing treatment with such medications, the increased levels of cortisol may change many important functions of the body. In such cases, a signal goes to the hypothalamus directing it to stop producing ACTH. When the production of ACTH is stopped, it neutralizes the adrenal cortex, which also stops production. Hence, it is important to gradually reduce the dosage of cortisol with a view to give enough time to these hormones to reactivate them. In case an individual stops the cortisol treatment abruptly and before due time, it is possible that the levels of cortisol will drop to a dangerously low levels. This can actually result in a major risk of developing infections and also cause general debility as well as weight loss. Until the adrenal glands come on-stream again and start making hormones, they are unable to respond, even to a slight emergency. In such cases, even a small ailment or wound may also result in a sudden and unforeseen death.
This is the deepest layer of the adrenal cortex and it is entrusted with the job of producing the sex hormones - estrogen and androgen. It is important to note that the gonads and not the adrenal glands are the original resource of these sex hormones. However, the adrenal glands definitely have a crucial role to play, as they provide the males with some amount of the female hormone estrogen and females with some amount of the male hormone androgen.
While the effects of estrogen in men are very less, the effect of androgen in women is more obvious. During puberty, androgen brings about various changes in girls, who start growing hairs in their pubic region and under their arms. In addition, androgen may also cause the voices of the girls to become slightly deeper and they also begin to experience the initial arousing of sexual desire owing to the action of the male hormone in them. Androgen also causes some disadvantages, for instance, it is believed that this male hormone is responsible for eruption of acne in girls/boys during their adolescent.
The adrenal glands’ internal parts are called the medulla. If you have been speculating about the location of adrenaline or where it is stored, you now know that this is the place. Two hormones are secreted by the medulla - epinephrine, which is commonly known as adrenaline; and norepinephrine, which is also called noradrenaline. Among these two hormones, adrenaline is more potent and also the main hormone, which makes up nearly 80 per cent of the hormones secreted by the medulla.
Impulses sent by the nerves stimulate the medulla to force adrenaline as well as noradrenaline into our bloodstream. People who have been frightened when a door is slammed, almost been flattened under a truck or have been stalked in a dark alley are aware what it precisely feels when there is a gush of these hormones. Simply put, the heart starts racing and one starts breathing more rapidly. All of a sudden you become very alert. And your muscle system perks up to such an extent that it suddenly possesses the aptitude to perform amazing feats just within a few seconds.
In such circumstances, your body prepares you to face the urgent situation or remove yourself physically from the crisis. Way back, in 1931, a scientist from the Harvard University, Dr. Walter Cannon, put together the emergency theory regarding secretion of adrenaline. When Dr. Cannon was undertaking tests on a cat, he observed that the circulation of blood from the adrenal gland was usual when the cat was calm. However, the hormonal balance of the cat was changed significantly when he allowed a dog to enter his laboratory. All off a sudden there was excessive secretion of adrenaline and it gushed to the animal’s blood circulation.
Adrenaline as well as noradrenaline always function in conjunction with cortisol, the hormone secreted by the adrenal cortex. When one faces an emergency situation, these hormones provide immediate preparedness to perform any unusual physical task and also supply the energy that is required to accomplish such task. While the responses of these hormones are very useful as far as our survival mechanism is concerned, it may also cause some problems when such reactions are kicked off very often.
It is very unfortunate that in our contemporary society, we are frequently subjected to excessive amounts of stress every day and our body may possibly respond to such stresses in a manner as if we are continuously facing a small emergency situation. While a traffic jam, a deadline, a final examination or failing to attend an appointment is seldom a critical situation, there are several people who get highly agitated about such common happenings.
People who almost spend their whole life confronting various crisis or emergency situations are usually categorized as what is referred to as the ‘type A’ persona. It always seems that such people are in a hurry and are facing an ongoing stress. Usually, this type of personality is impatient and prefers to be in total control of any situation instead of passing on responsibilities to other people. Very frequently they claim that the best in them comes out when they are under stress.
It can be extremely serious if the action of the hormones is heightened and also continues for a prolonged period of time. The secretion of stress hormones on an almost continuous basis puts an additional burden on our body. In such situations, the immune system may be down, making the body further vulnerable to diseases and infections. In addition, it may even damage the cardiovascular system, as there is an extended and regular rise in one’s blood pressure. As a result of this, the chances of developing a stroke or heart attack increase. Ongoing medical studies reveal that when we experience extended periods of stress we also face an increased risk of developing anorexia nervosa, cancer, and weakened sexual drive, while our growth may also be suppressed. Therefore, identifying this behaviour and controlling it may possibly save the life of people who belong to the ‘type A’ category.
Some scientific studies seem to even relate stress to a scarcity of brain cells. A number of scientists are of the view that this may also be responsible for the rapidly increasing Alzheimer’s disease in the contemporary society. Usually this ailment afflict both men as well as women above the age of 50 years and it is distinguished by a gradual failure of one’s mental ability, great confusion as well as memory lapses.
While the adrenal cortex as well as the medulla function in conjunction to deal with stress, a significant disparity exists between them too. The adrenal cortex mainly responds to stimulation by pituitary, on the other hand, the medulla reacts to electrical impulses directly sent by the nervous system. Luckily enough, in case of an emergency, the nervous system possesses the aptitude to perform the tasks of adrenaline as well as noradrenaline. Even as the nervous system stimulates the adrenal medulla, it sends signals directly to the lungs, heart as well as various other important organs. This action of the nervous system offers us a system that never fails. Despite the fact that the consequences of the impulses/ signals sent by the nervous system are at least 10 times less powerful compared to the normal signals sent by the hormones, the adrenal medulla’s hypo functioning may be excluded as a severe problem. On the contrary, the hyper function that is often set off by a tumour needs to be treated timely and appropriately. In such instances, undergoing a surgery or taking drug therapy for a prolonged period may prove to be effectual.