Anatomy & Organs

Hormone system – structure, function & diseases

Hormonal system

As a complex system, the hormone system controls the coordination of the functions of all organs of the organism. In humans, more than thirty different hormones (transmitters) are responsible for this. The medical specialty of endocrinology deals with disorders within the endocrine system.

What is the endocrine system?

The endocrine system includes both endocrine glands and isolated cell groups in other organs, which produce so-called hormones (transmitters). These hormones are either carried endocrine via the bloodstream to the target organs or have a paracrine effect on neighboring cells.

Within the hormone system (endocrine system), the production of the individual hormones is well coordinated. There are messenger substances that act directly on the target organs. Other hormones have regulatory tasks. They control the production of other hormones. The hormone system is linked to the central nervous system via the hypothalamus . The hypothalamus is considered the superordinate control organ of all endocrine glands and produces releasing and inhibiting factors (hormones that promote or inhibit downstream hormone production).

The basis of their function is the conversion of processed sensory impressions into physical reactions via the endocrine system. The close coupling of the nervous system with the hormone system is summarized under the term neuroendocrine system.

Anatomy & Structure

The endocrine system consists of various endocrine glands distributed throughout the body and isolated groups of hormone-producing cells from other organs. Endocrine glands include the pituitary , thyroid , parathyroid , pineal , adrenal , or islets of Langerhans from the pancreas .The corpus luteum, ovarian follicles in the ovary and the Leydig cells in the testicles are just as much a part of the endocrine system as the paraganglia, which, as a collection of nerve cell bodies, link the endocrine system and the nervous system to form the neuroendocrine system due to their partial endocrine function. Furthermore, all epithelia contain endocrine cells , the hormones of which, however, usually have a paracrine effect (on the neighboring tissue). The pituitary gland (pituitary gland) is the link between the hypothalamus and the subordinate endocrine glands.

While the hypothalamus still belongs to the central nervous system as part of the cerebellum , the pituitary is already an endocrine gland. It can thus be seen as the link between the nervous and endocrine systems. The pituitary gland produces a variety of hormones that regulate or act directly on the target organ. As the central endocrine organ, it controls the functions of the other endocrine glands.

The production of the individual hormones is controlled by a control circuit. For example, if there are too few thyroid hormones, the pituitary gland is stimulated to produce the thyroid-stimulating hormone TSH. The same applies vice versa. For example, in addition to the thyroid gland, the adrenal glands or the gonads are also subject to this regulatory mechanism within the hormone system.

Function & Tasks

The messenger substances produced within the endocrine system each have individual functions in the target organs. The islets of Langerhans in the pancreas are responsible for the production of insulin . Insulin regulates blood sugar levels . A lack of insulin leads to diabetes . The thyroid, in turn, produces thyroid hormones that stimulate metabolism . The metabolism slows down when there is a thyroid hormone deficiency.

Conversely, when there is an excess of thyroid hormones, the metabolism accelerates. The sex hormones in turn regulate the primary and secondary development of sex characteristics and have a significant influence on sexual behavior. Various glucocorticoids are produced in the adrenal glands. These are steroid hormones whose basic building block is cholesterol .

Glucocorticoids fulfill different tasks. They affect the metabolism, are responsible for the mineral balance, have an impact on the cardiovascular system and have an anti-inflammatory and immunosuppressive effect. Cortisol as a representative of the glucocorticoids, for example, controls gluconeogenesis (conversion of proteins into carbohydrates ). The hormones produced (anterior pituitary) or stored (posterior pituitary) in the pituitary gland have different functions. STH ( somatotropin , growth hormone), prolactin or melanotropin have a direct effect on the target organs. Somatropin regulates growth.

Prolactin is responsible for milk production during breastfeeding and melanotropin stimulates the growth of melanocytes. The hormones TSH, ACTH, FSH and LH stimulate the thyroid, the adrenal cortex or the gonads in this order. The hormones vasopressin and oxytocin , which come from the hypothalamus, are stored in the neurohypophysis (posterior pituitary gland) and released when needed.

While vasopressin (antidiuretic hormone) regulates water absorption in the kidneys , oxytocin is responsible for the contraction of the smooth muscles of the uterus at birth . Various scattered endocrine cells of the endocrine system in the heart , kidneys, liver , gastrointestinal tract , thymus , central nervous system and other organs each perform specific functions.

Diseases

Diseases within the endocrine system manifest themselves in different ways. If specific organs are affected, there can be a deficiency, failure or excess of individual hormones with the corresponding health problems. For example, a lack of insulin causes diabetes.If the thyroid gland is underactive , the metabolism and thus all bodily functions slow down. Hypothyroidism manifests itself in severe weight loss, nervousness , higher heart rate and diarrhea . An overproduction of cortisol causes the so-called Cushing’s syndrome with trunk obesity and increased susceptibility to infections. A loss of function of the adrenal gland leads to potentially life-threatening Addison’s disease due to a lack of cortisol and a lack of mineral corticosteroids.

If the anterior pituitary fails, a whole range of hormones are affected. The functional failure of the adenohypophysis , known as Sheehan’s syndrome , manifests itself in a combination of symptoms from different hormone deficiency states. Lifelong hormone replacement is often required. If the sex hormones are affected by hormone disorders, hypogonadism , sexual dysfunction or infertility often occur . Since the endocrine system and the nervous system are closely linked, mental disorders can also have an impact on the endocrine system.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.