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 the adrenal glands, two small organs responsible for secreting hormones such as cortisol, adrenaline or norepinephrine into the bloodstream.
In this article we explain what the adrenal glands are what is their structure, what functions do they perform in our body and what are the most common diseases and disorders related to poor functioning of these glands.
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 external 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 estrogen.
The adrenal cortex and adrenal medulla are enveloped in a fatty capsule that forms a protective layer around the adrenal gland. The adrenal cortex is essential for our survival; If it stopped functioning correctly, it is very likely that collapse and death would occur, 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 responsible for secreting “stress hormones,” such as adrenaline and norepinephrine. Let’s see in more detail what they consist of and what the functions of these and other hormones produced in the adrenal glands are.
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 the way the body responds to stress, and as we have discussed previously, 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. For the adrenal gland to produce cortisol, the following occurs: First, the hypothalamus produces corticotropin-releasing hormone (CRH) which 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 negative feedback loop ). 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 other source.
2. Aldosterone
Aldosterone is a mineralocorticoid hormone produced by the zona glomerularis of the adrenal cortex and plays a central role in regulating 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 testes into male hormones (androgens).
However, the ovaries and testes produce estrogens and androgens in much greater quantities.
4. Adrenaline and norepinephrine
The adrenal medulla controls the hormones that initiate the fight or flight response The main hormones secreted by the adrenal medulla include epinephrine (adrenaline) and norepinephrine (norepinephrine), which have similar functions.
Among other functions, these hormones are capable of increasing heart rate and the force of heart contractions, increasing blood flow to the muscles and brain, relaxing the smooth muscles of the airways, and helping with glucose (sugar) metabolism. .
They also control the compression of blood vessels (vasoconstriction), which helps maintain blood pressure and increase it in response to stress. Like other hormones produced by the adrenal glands, adrenaline and noradrenaline are often activated in situations of physical and emotional stress when the body needs additional resources and energy to withstand unusual stress.
The adrenal glands are an intricate part of the hypothalamic-pituitary-adrenal axis The hypothalamus acts as the body’s thermostat and detects 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 estrogens, adrenaline and cortisol, are produced by the adrenal glands. One of the main activities of cortisol is to increase glucose available to the nervous system by breaking down proteins and fats into glucose in the liver, helping to block glucose absorption in tissues other than the central nervous system.
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 flood of hormones such as adrenaline and cortisol, and these increase heart rate, raise blood pressure, increase energy supplies, sharpen concentration, and slow down other bodily processes so the body can escape or combat a threat.
However, an excessive stress response can be counterproductive. Excess exposure to stress hormones from the adrenal gland can cause anxiety, depression, digestive problems, headaches, heart disease, sleep problems, weight gain, and impaired memory and concentration. Below are the most common disorders related to excess production of adrenal hormones.
Related disorders
The two most common ways the adrenal glands cause health problems are by producing too little or too much of certain hormones, which leads to hormonal imbalances.
These abnormalities of adrenal function can be caused by various diseases of the adrenal glands or pituitary gland. Let’s look at the main disorders related to abnormal functioning of the adrenal glands
1. Adrenal insufficiency
Adrenal insufficiency is a rare disorder. It can be caused by disease of the adrenal glands (primary adrenal insufficiency or Addison’s disease) or by diseases of the hypothalamus or pituitary gland (secondary adrenal insufficiency). 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 may include autoimmune disorders, fungal and other infections, cancer (rarely), and genetic factors. Although adrenal insufficiency usually develops over time, it can also appear suddenly as acute adrenal insufficiency (adrenal crisis). It has similar symptoms, but the consequences are more severe, including life-threatening seizures and coma.
Adrenal insufficiency can also be the result of a genetic disorder called congenital adrenal hyperplasia. Children born with this disease lack an essential enzyme needed to produce cortisol, aldosterone, or both. At the same time, they often experience an excess of androgens, which can lead to masculine characteristics in girls and precocious puberty in boys.
Congenital adrenal hyperplasia can remain undiagnosed for years, depending on the severity of the enzyme deficiency. In more severe cases, babies may suffer from ambiguous genitalia, dehydration, vomiting, and failure to thrive.
3. Cushing’s syndrome
Cushing’s syndrome occurs due to excessive production of cortisol in the adrenal glands.
Symptoms may include weight gain and fat deposits in certain areas of the body, such as the face, under the back of the neck (called buffalo hump), and in the abdomen; thinning of arms and legs; purple stretch marks on the abdomen; facial hair; fatigue; muscular weakness; easily bruised skin; high blood pressure; diabetes; and other health problems.
Excessive cortisol production can also be triggered by overproduction of adrenocorticotropic hormone (ACTH), a benign tumor in the pituitary gland, or a tumor elsewhere in the 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 or inflammatory diseases.
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 may develop low levels of potassium in the blood, which can cause muscle pain, weakness, and spasms.
5. Pheochromocytoma
Pheochromocytoma is a tumor that causes excess production of adrenaline or norepinephrine in the adrenal medulla. Sometimes, the neural crest tissue (a structure of few cells that exists transiently in early stages of embryonic development), which has a tissue similar to the adrenal medulla, can 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 developing this type of tumor.
