Adrenal glands: functions, characteristics and diseases

Our endocrine system is made up of a set of organs and tissues that are responsible for regulating vital functions for our body through the release of different hormones.

Aspects as important for survival as the proper functioning of the metabolism or the immune system depend, to a large extent, on extent, from the adrenal glands, two small organs responsible for secreting hormones such as cortisol, adrenalin wave norepinephrine.

In this article we explain what the adrenal glands are, what is its structure, what functions do they perform in our body and what are the most common diseases and disorders related to a malfunction of these glands.

Adrenal glands: definition and structure

The adrenal glands are small, triangular-shaped endocrine organs located on top of both kidneys.. These glands are responsible for producing hormones that help regulate metabolism, the immune system, blood pressure, stress response, and other essential functions.

Each person has two adrenal glands, which can be divided into two parts: the outer portion, called the adrenal cortex; and the internal portion, which is called the adrenal medulla. The adrenal cortex is responsible for creating three different types of hormones: mineralocorticoids that conserve sodium in the body, glucocorticoids that increase blood glucose levels, and gonadocorticoids that regulate sex hormones such as he

estrogen.

The adrenal cortex and adrenal medulla are wrapped in a fatty capsule that forms a protective layer around the adrenal gland. The adrenal cortex is essential for our survival; if it stopped working properly, it is very likely that there would be a collapse and death, since it controls the basic metabolic processes for life.

For its part, the adrenal medulla, which is located within the adrenal cortex in the center of the gland, is in charge of secreting the "stress hormones", such as adrenaline and norepinephrine. Let's see in more detail what they consist of and what are the functions of these and other hormones produced in the adrenal glands.

Hormones of the adrenal glands

The role of the adrenal glands in our body is to release certain hormones directly into the bloodstream., many of which have to do with how the body responds to stress, and as we've discussed above, some are vital for survival.

Both parts of the adrenal glands, the adrenal cortex and the adrenal medulla, perform distinct and separate functions, and each area of ​​the adrenal cortex secretes a specific hormone. Let's see below what are the key hormones produced by the adrenal cortex:

Cortisol is a glucocorticoid hormone produced by the zona fasciculata that plays several important roles in the body.. Helps control the body's use of fats, proteins, and carbohydrates; suppresses inflammation; regulates blood pressure; increases blood sugar; and can also decrease bone formation. This hormone also controls the sleep-wake cycle, and is released during times of stress to help the body get a boost of energy and better handle an emergency situation.

The adrenal glands produce hormones in response to signals from the pituitary gland in the brain, which reacts to signals from the hypothalamus. This is known as the hypothalamic-pituitary-adrenal axis. In order for the adrenal gland to produce cortisol, the following occurs: First, the hypothalamus produces cortisol. corticotropin-releasing hormone (CRH) that stimulates the pituitary gland to secrete adrenocorticotropic hormone (ACTH).

The hormone ACTH then stimulates the adrenal glands to produce and release cortisol into the blood (if there is too much or too little cortisol, these glands respectively change the amount of CRH and ACTH that is released, in what is known as a feedback loop negative). Excessive production of cortisol can occur from nodules in the adrenal gland or excessive production of ACTH from a tumor in the pituitary gland or another source.

2. aldosterone

Aldosterone is a mineralocorticoid hormone produced by the zona glomerulosa of the adrenal cortex. and plays a central role in the regulation of blood pressure and certain electrolytes (sodium and potassium).

This hormone sends signals to the kidneys, causing them to absorb more sodium into the bloodstream and release potassium into the urine. This means that aldosterone also helps regulate blood pH by controlling electrolyte levels in the blood.

3. DHEA and androgenic steroids

DHEA and androgenic steroids are produced by the zona reticularis of the adrenal cortex., and are precursor hormones that are converted in the ovaries into female hormones (estrogens) and in the testicles into male hormones (androgens).

However, the ovaries and testicles produce estrogens and androgens in much larger amounts.

4. adrenaline and norepinephrine

The adrenal medulla controls the hormones that initiate the fight or flight response.. The major hormones secreted by the adrenal medulla include epinephrine (adrenaline) and norepinephrine (noradrenaline), which have similar functions.

Among other functions, these hormones are capable of increasing the heart rate and the force of cardiac contractions, increasing the blood flow to the muscles and brain, relax the smooth muscles of the airways, and aid glucose metabolism (sugar).

They also control the compression of blood vessels (vasoconstriction), which helps maintain blood pressure and increases it in response to stress. Like other hormones produced by the adrenal glands, adrenaline and norepinephrine are often activated in situations of physical and emotional stress when the body needs additional resources and energy to withstand stress unusual.

functions

The adrenal glands are an intricate part of the hypothalamic-pituitary-adrenal axis.. He hypothalamus It acts as the body's thermostat, sensing most of the important physiological elements involved in homeostasis, sending signals to correct perceived harmful variations.

It connects directly to the pituitary gland, which essentially picks up orders from the hypothalamus and sends signals to various organs and glands, including the adrenal glands, to carry out these orders.

A wide range of hormones, including estrogen, adrenaline, and cortisol, are produced by the adrenal glands. One of cortisol's main activities is to increase glucose available to the nervous system by breaking down proteins and fats into glucose in the liver, helping to block glucose uptake in tissues other than the system central nervous.

Cortisol also has powerful anti-inflammatory and anti-allergic actions, and decreases the activities of the immune system to reduce inflammatory conditions.

Another of the most important functions of the adrenal glands is the fight or flight response. When a person is stressed or scared, the adrenal gland releases a torrent of hormones., such as adrenaline and cortisol, and these increase heart rate, raise blood pressure, increase supplies energy, sharpen concentration, and slow down other bodily processes so the body can escape or fight a threat.

However, an excessive stress response can be counterproductive. Excess exposure to stress hormones from the adrenal gland can cause anxiety, depression, problems digestive disorders, headaches, heart disease, sleep problems, weight gain, and impaired memory and concentration. The following are the most common disorders related to an excess production of adrenal hormones.

Related disorders

The two most common ways that the adrenal glands cause health problems are producing too little or too much of certain hormones, leading to imbalances hormonal.

These adrenal function abnormalities can be caused by various diseases of the adrenal glands or the pituitary gland. Let's see the main disorders related to the abnormal functioning of the adrenal glands.

1. Suprarrenal insufficiency

Adrenal insufficiency is a rare disorder. It can be caused by a disease of the adrenal glands (primary adrenal insufficiency or the Addison's disease) or diseases of the hypothalamus or pituitary gland (adrenal insufficiency secondary). This condition is characterized by low levels of adrenal hormones and symptoms include: weight loss, lack of appetite, nausea and vomiting, fatigue, darkening of the skin (only in primary adrenal insufficiency), and abdominal pain, among others.

Causes of primary adrenal insufficiency can include autoimmune disorders, fungal and other infections, cancer (rarely), and genetic factors. Although adrenal insufficiency usually develops over time, it can also come on suddenly as acute adrenal insufficiency (adrenal crisis). It has similar symptoms, but the consequences are more serious, including life-threatening seizures and coma.

2. congenital adrenal hyperplasia

Adrenal insufficiency can also be the result of a genetic disorder called congenital adrenal hyperplasia. Children born with this disease are missing an essential enzyme needed to produce cortisol, aldosterone, or both. At the same time, they often experience androgen excess, which can lead to masculine characteristics in girls and precocious puberty in boys.

CAH can go undiagnosed for years, depending on the severity of the enzyme deficiency. In more severe cases, babies can suffer from ambiguous genitalia, dehydration, vomiting, and failure to thrive.

3. Cushing's syndrome

Cushing's syndrome is caused by excessive production of cortisol in the adrenal glands.

Symptoms can include weight gain and fatty deposits in certain areas of the body, such as the face, under the back of the neck (called the buffalo hump), and on the abdomen; slimming of arms and legs; purple streaks on abdomen; facial hair; fatigue; muscular weakness; easily bruised skin; high blood pressure; diabetes; and other health problems.

Excess cortisol production can also be triggered by overproduction of the hormone. adrenocorticotropin (ACTH), from a benign tumor in the pituitary gland or a tumor in another part of the body body. This is known as Cushing's disease. Another common cause of Cushing's syndrome is excessive and prolonged use of external steroids, such as prednisone or dexamethasone, which are prescribed to treat many autoimmune diseases or inflammatory.

4. Hyperaldosteronism

Hyperaldosteronism is a disorder caused by the overproduction of aldosterone in one or both adrenal glands.

This causes an increase in blood pressure that often requires many medications to control. Some people can develop low levels of potassium in their blood, which can cause muscle aches, weakness, and spasms.

5. Pheochromocytoma

Pheochromocytoma is a tumor that causes excess production of adrenaline or norepinephrine in the adrenal medulla. Sometimes neural crest tissue (a structure of few cells that exists transiently in early stages of embryonic development), which has tissue similar to the adrenal medulla, may be the cause of the overproduction of these hormones, which is known as paraganglioma.

Pheochromocytomas can cause persistent or sporadic high blood pressure that can be difficult to control with common medications. Other symptoms include: headaches, sweating, tremors, anxiety, and rapid heartbeat. Some people are genetically predisposed to develop this type of tumor.

Bibliographic references:

• Fardella, B. (2001). Congenital adrenal hyperplasia. Chilean Journal of Pediatrics, 72(5), 408-415.

• Rosol, T. J., Yarrington, J. T., Latendresse, J., & Capen, C. c. (2001). Adrenal gland: structure, function, and mechanisms of toxicity. Toxicologic pathology, 29(1), 41-48.

• Tsigos, C., & Chrousos, G. Q. (2002). Hypothalamic–pituitary–adrenal axis, neuroendocrine factors and stress. Journal of psychosomatic research, 53(4), 865-871.