What is the adrenal cortex?
The adrenal cortex, together with the adrenal medulla, forms a paired endocrine gland called the adrenal gland. Every human has two adrenal glands. They are located on the upper poles of both kidneys. Functionally, the adrenal glands represent two distinct organs.
While the adrenal cortex produces steroid hormones and is involved in the mineral water and sugar balance, the adrenal medulla, with the help of the hormones epinephrine and norepinephrine, exerts a decisive influence on the sympathetic nervous system. The adrenal cortex, which is also called the cortex glandulae suprarenalis, looks yellowish due to its lipid content.
As bark, it forms the outer part of the adrenals. It produces over 40 different steroid hormones called corticosteroids. In tribal history, the bark and the marrow are two separate organs in fish. In amphibians and reptiles, both organs already encamped. It is only in mammals and birds that the adrenal cortex and adrenal medulla are so closely linked that, despite their different functions, they can be viewed externally as one unit.
Anatomy & ConstructionAs already mentioned, the adrenal cortex encloses the adrenal medulla and together with it forms the adrenal gland. Both adrenals are paired and occupy each of the upper poles of the kidneys. They are surrounded by a fine connective tissue capsule. The adrenal cortex can be divided into three layers. The outer layer, also called zona glomerulosa, is arranged in a nodule-like manner in humans. It produces the hormone aldosterone for mineral metabolism and has a total of 15 percent of the adrenal cortex. The largest proportion, approximately 78 percent, is the middle layer, the zona fasciculata . She is responsible for the production of glucocorticoids, such as cortisol. With a relatively small proportion of about 7 percent, the lower portion of the adrenal cortex, the zona reticularis, controls the formation of sex hormones.
However, all three zones are dynamic. Their expression changes constantly in the course of life. Thus, their size ratio shifts after puberty in favor of zona glomerulosa and zona reticularis. The delimitation of the two functional parts of the adrenal glands is also already expressed by its different origin. While the adrenal cortex is of mesodermal descent, the adrenal medulla originally forms from nerve cells.
Function & Tasks
The adrenal cortex controls both the mineral metabolism and the sugar balance, releases so-called stress hormones during stress and is involved in the formation of sex hormones. Despite seemingly different functions, they all have in common that they depend on steroid hormones (corticosteroids). The synthesis of all hormones of the adrenal cortex via the cholesterol, also called cholesterol.
The hormone aldosterone is produced in the zona glomerulosa. This hormone balances the sodium and potassium levels in the blood.
In the middle zone, the zona fasciculata, the synthesis of so-called glucocorticoids, including cortisol, takes place. Cortisol is a stress hormone and has a major influence on blood sugar levels. A stress reaction requires an increased release of energy, which can only be guaranteed by a rapid supply of glucose from the body's own proteins. So with the release of cortisol and the blood sugar level rises.
The third zone, the so-called zona reticularis, produces predominantly androgens, which act as precursors to sex hormones. The formation of steroid hormones is embedded in the entire regulatory mechanism of the hormonal system. Thus, the pituitary gland produces adrenocortical hormone regulating hormone, also called ACTH. Disruptions in this control mechanism sometimes lead to serious hormonal diseases. The causes of these diseases can be found primarily in the adrenal cortex as well as secondarily in the pituitary gland.
Diseases & complaints
Due to the many hormones produced in the adrenal cortex, it can lead to different clinical pictures. Known hormone disorders are expressed, for example, as Conn's syndrome, as Cushing's syndrome or as Addison's disease. Conn syndrome is based on overproduction of the hormone aldosterone and is also called primary hyperaldosteronism.
It is characterized by a lack of potassium and is a rare cause of high blood pressure. Symptoms of this disease include hypertension, angina pectoris, headache, dyspnoea and arrhythmia. The increased production of aldosterone can be caused by genetic causes, an adrenocortical adenoma or enlargement of the adrenal cortex.
In Cushing's syndrome too much cortisol is released. This leads to an increase in blood sugar levels and suppression of the immune system. Characteristic symptoms are full moon face, Stammfettsucht, diabetes, increased blood pressure, edema and increased susceptibility to infections. The increased cortisol production can be caused primarily by an adenoma on the adrenal cortex or secondarily by diseases of the pituitary gland.
Treatment will be based on the underlying condition. A subproduction of cortisol leads to the so-called Addison's disease. Addison's disease is characterized by general weakness, susceptibility to infection, low blood pressure, indigestion, weight loss and brownish discoloration of the skin. The low production of cortisol may be caused primarily by diseases of the adrenal cortex, secondarily by disorders of the pituitary gland, and tertiary by regulatory disorders in the treatment with corticosteroids.
For example, if a cortisone treatment abruptly stopped, it often comes to the so-called Addison crisis, because the control mechanism of the body's own cortisol synthesis works only with delay. Primary parathyroid dysfunction is often caused by infections, autoimmune diseases, or tumors and is sometimes genetic.