THE ADRENAL GLANDS
The adrenal or supra-renal glands are two glands located on the upper portion of each kidney. From here, they release the hormones in the bloodstream. It is triangular and about three inches in length and 1.5 inches in height. This gland also referred to as ‘Glands of Emergency’. The role of the adrenal glands is alertness, growth, and more.
Each adrenal gland has two parts and each secretes hormones and has different functions. The outermost layer of the adrenal gland called the Adrenal cortex and the innermost layer known as the adrenal medulla.
ADRENAL GLAND-LOCATION
Image Source : Wikimedia Commons
ADRENAL GLAND
Image Source : Wikimedia Commons
Adrenal Cortex: This is the outermost part of the gland. The adrenal cortex secretes hormones that are significant to our life. The adrenal cortex produces steroids and metabolic hormones that help control salt and water balance in the body. The adrenal cortex is broken into three layers.
(i) Mineralocorticoids (Zona Glomerulosa): Produced by the outer layer of the adrenal cortex. It helps in maintaining both the electrolyte and water content of the body.
(ii) Glucocorticoids (Zona Fasiculata): Produced by the middle cortex. Glucocorticoids affects every cell in the body regulating the metabolism of fats, proteins, and carbohydrates.
(iii) Gonadal hormones (Zona Reticularis): Produced by the inner cortex. Two types of hormones secreted: Androgen in male and Estrogen in the female.
Adrenal Medulla: This is the innermost portion of the gland. The adrenal medulla discharges non-essential hormones. This hormone discharged in high amounts when the person is excited or scared. It aids the body to deal with stressful situations such as fright, attack. This increases heartbeat, blood pressure, and blood glucose levels, thus preparing the body for quick action.
HORMONES AND FUNCTIONS
The adrenal glands are managed by the brain. The hypothalamus releases Corticotropin-releasing hormone (CRH) and Vasopressin (also known as an antidiuretic hormone). This in turn kindles the pituitary gland to discharge adrenocorticotropic hormone or ACTH. ACTH provokes the adrenal glands to produce corticosteroids. Adrenal glands discharge several kinds of hormones.
Adrenal Cortex Hormones (corticosteroid hormones)
(i) Aldosterone: Aldosterone hormone released by the Mineralocorticoids. Aldosterone assists in the holding of sodium and the expulsion of potassium. Aldosterone conserves both the electrolyte (sodium ions) and water content in the body. The shortage of aldosterone caused when the body is under stress. Its indications vary from fatigue to dizziness and chronic nausea, low blood pressure, and low salt levels.
(ii) Cortisol (Hydrocortisone): Cortisol hormone released by the Glucocorticoids. Cortisol hormone reacts while physical, psychological stress, and when the bodies’ sugar level drops down. When the sugar level decreases, cortisol stimulates gluconeogenesis helping in the breakdown of food to balance the sugar level in the body. Cortisol also regulates the conversion of fats, proteins, and carbohydrates to energy. Cortisol stabilizes blood pressure and cardiovascular function.
During a panic situation, Cortisol hormone increases heart rate, blood pressure, respiration, etc. In the time of stress, cortisol released to balance the situation.
If cortisol secreted more than the requirement it causes ulcers, blood pressure, anxiety, and increases the cholesterol level. Furthermore, a low level leads to alcoholism, chronic fatigue syndrome.
Cortisol also subdues the immune system and bone formation.
(iii) Corticosterone: Corticosterone is another hormone released from the Glucocorticoids. Corticosterone hormone works along with the Cortisol to maintain the immune system and restrain the inflammatory reactions.
(iv) Androgens: Androgens hormone released by the gonadocorticoids or sex hormones/sex steroids. The adrenal cortex discharges little amounts of male and female sex hormones. The transformation happens once puberty starts. The variations might be pubic hair growth, Adam’s apple formation, muscle, and hair growth.
Adrenal Medulla Hormones
The hormones from the adrenal Medulla secreted, if the sympathetic nervous system got stimulated. The sympathetic nervous system stimulated during the stress condition. Adrenal Medulla Hormones helps during physical, emotional stress i.e. when the body encounters a threatening (stressful) situation. The Adrenal medulla develops from neural tissue. Hormones discharged by the adrenal medulla are:
1) Epinephrine: Epinephrine hormone also referred to as adrenaline. Epinephrine controls blood sugar levels by transforming glycogen to glucose in the liver. Epinephrine hormone reacts swiftly by raising the heartbeat, hurries blood into the muscles and brain. Epinephrine hits both alpha and beta receptors in the nervous system.
2) Norepinephrine: Norepinephrine hormone also referred to as noradrenaline. Norepinephrine hormone works along with epinephrine. Norepinephrine hormone can cause the narrowing of blood vessels (vasoconstriction) resulting in high blood pressure. Norepinephrine influences solely the alpha-receptors of the nervous system.
The hormones from the adrenal medulla, when secreted in low amounts, do not cause any problems but if the secretion is more it leads to tumour resulting in prolonged sympathetic responses.
DISORDERS
There are several reasons for the improper function of adrenal glands. The reason might be in the adrenal gland itself or the cause might be in the other glands in the body. The common disorders and diseases are:
(i) Addison’s disease: This is an uncommon disease, which attacks any age group. Adrenal glands influenced by an autoimmune reaction in which the body’s immune system hits and ruins the adrenal cortex. The reason for this disease is that the adrenal cortex does not discharge a sufficient amount of cortisol and aldosterone hormones. Thus, Addison's disease influences the stability of water, sodium, and potassium in the body. This disease may occur due to the genetic malformation of the adrenal glands.
Darkening of the gums due to the Addison's disease
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Darkening of the skin of a white person with Addison's disease
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(ii) Adrenal cancer: This disease is so aggressive and found rarely. There are two types of tumours found in this case. The ‘functioning tumour’ will prolong to secrete the hormones cortisol, aldosterone and androgens. The ‘Non-functioning tumour’ does not produces or secrete any hormones resulting in deficiencies. The excess hormone secretion disseminates to other organs resulting in dreadful changes within the body.
(iii) Cushing’s syndrome: This is just the opposite of Addison’s disease and found rarely. This syndrome caused due to the hypersecretion of cortisol. The hypersecretion may be in the Pituitary gland, (if tumour found in the pituitary gland it secretes more corticotrophin) cancer found in the lungs (carcinoid tumour), or somewhere in the body. A person with this syndrome tend to tire easily, has a big round face. Muscles become weak. The skin becomes thin and if it is injured, does not cure easily. Women have an irregular menstrual cycle. Children grow slowly and remain dwarf.
A Linear mark with Cushing’s syndrome
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Baby with round face, acne, reddish skin, central obesity, and poor muscle tone
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The therapy for this syndrome relies on whether the issue is in the adrenal glands, the pituitary gland, or elsewhere. If the complication is in the Pituitary gland then surgery or radiation therapy needed to eliminate or destroy a pituitary tumour. If the tumour found in the adrenal glands then the tumour might be detached by surgically. Tumors found external to the pituitary and adrenal glands that discharge excess hormones surgically amputated.
(iv) Congenital adrenal hyperplasia: This disease is due to the genetic disorder because of the hypo secretion of cortisol and aldosterone.
(v) Hyperaldosteronism: This occurs because of a tumour in the adrenal gland or some other diseases. Hypersecretion of aldosterone results in high blood pressure and low potassium levels. Lack of potassium causes weakness, tingling, muscle spasms, and periods of temporary paralysis. If there is a tumour, it removed surgically. If there is no tumour found and both glands are hyperactive, treatment with corticosteroids for life is the solution.
(vi) Adrenal Pheochromocytoma: A pheochromocytoma is a tumour that arises in the adrenal medulla and is very rare. Pheochromocytomas occur in men as well as in women of all age groups, but they are most general in people between the ages of 20 and 40.
A small pheochromocytoma produces more catecholamines. Catecholamines are hormones so as adrenaline (epinephrine), norepinephrine, and dopamine; it raises blood pressure and heart rate together with life-threatening circumstances.
The most important symptom is high blood pressure, which is very severe. The other symptoms include sweating, rapid breathing, headaches, nausea, vomiting, stomach and chest pain, constipation, vision problem.
This disease treated via surgery (removal of tumour) or by drugs, that controls blood pressure.
(vii) Virilization: It is the growth of masculine traits in women. This is because of the hypersecretion of androgens. Hypersecretion is due to the tumour or expansion of an adrenal gland or tumour in an ovary or irregular hormone production by the ovaries.
The symptoms are the growth of hair in the face and body (hirsutism), baldness, acne, deepening of the voice, increased muscularity, and an increased sex drive. In women, the uterus shrivels, the clitoris expands, the breasts become tinier, and normal menstruation stops. In men, it suppresses the function of the testes and causes infertility.
This disorder treated through surgery by removing the adrenal gland, which has tumour.
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