What Are Hormones? (Definition)
Hormones are chemical messengers produced by endocrine glands and released into the bloodstream. They regulate metabolism, growth, mood, fertility, immune response and adaptation to stress.
Hormones are biologically active signalling molecules (chemical messengers) produced by endocrine glands and released into the bloodstream. Their main function is to transmit information between cells, tissues and organs in order to coordinate vital bodily processes such as metabolism, growth, development, immune response, mood and reproduction. Hormones work by binding to specific receptors on target cells and triggering a particular biological response. The most important human hormones include oestrogen, progesterone, testosterone, insulin, cortisol and thyroid hormones.
What are hormones? Hormones are chemical messengers that coordinate the function of nearly all organs in the body. They are biologically active signalling molecules synthesised by endocrine glands and released directly into the bloodstream.
What Are Hormones and Why Are They Important?
Hormones are important because the body cannot function in a coordinated way without them. They regulate every process — from metabolism and growth to mood and reproduction. Hormonal imbalance causes symptoms that affect quality of life.
What are hormones, and why are they so vital to our health? Hormones are chemical messengers that regulate virtually every process in the body — from metabolism and growth to mood and fertility. When we understand what hormones are and how they work, it is easier to recognise signs of hormonal imbalance and seek appropriate support. In practical terms, this is what hormones are: without them, our bodies could not function in a coordinated way.
Hormones are biologically active signalling molecules synthesised by endocrine glands or individual specialised cells and released directly into the bloodstream. Their basic function is to transmit information between different organs and tissues, enabling the body to function in a coordinated way. Together with the nervous system, they form one of the most important regulatory systems for homeostasis, participating in the regulation of metabolism, growth, development, reproduction, immune response, fluid balance and the body's adaptation to stressors. Unlike the nervous system, which acts quickly and briefly through electrical impulses, hormones act more slowly, but their effects often have a longer-lasting influence on the function of target cells.
The term hormone derives from the Greek word hormao, meaning “to stimulate” or “to arouse”. It was introduced in 1905 by Ernest Starling and William Bayliss after their discovery of secretin, the first hormone to be described. Their discovery laid the foundations of modern endocrinology and demonstrated that chemical substances can transmit information through the blood between different organs without a direct neural connection. Today it is known that, in addition to the classical endocrine glands, many other tissues and organs also produce hormones, including the heart, kidneys, digestive tract, adipose tissue, liver and placenta. The endocrine system is therefore now understood as a distributed signalling system throughout the body.
The endocrine system consists of the hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid glands, adrenal glands, pancreas (islets of Langerhans), ovaries and testes. The individual glands are connected through complex hormonal axes, the most important of which is the hypothalamic–pituitary–target organ axis. The hypothalamus synthesises releasing and inhibiting hormones that regulate secretion of hormones by the anterior pituitary, which in turn controls the activity of peripheral endocrine glands such as the thyroid, adrenal glands and gonads. This organisation enables precise regulation of hormonal balance.
Hormones act at extremely low concentrations, often in the range of picograms or nanograms per millilitre of blood. Their action is based on specific binding to receptors on target cells. Peptide and protein hormones bind to cell-membrane receptors, where they trigger intracellular signalling pathways through second messengers such as cyclic adenosine monophosphate (cAMP), inositol trisphosphate (IP₃), diacylglycerol (DAG) and calcium ions (Ca²⁺). Because of their lipophilic nature, steroid and thyroid hormones pass through the cell membrane and bind to intracellular receptors that act as transcription factors and directly regulate gene expression.
Most hormonal systems operate according to the principle of negative feedback (negative feedback regulation). An elevated concentration of a hormone in the blood inhibits further secretion of releasing hormones from the hypothalamus and trophic hormones from the pituitary, preventing excessive hormonal activity. A classic example is the hypothalamic–pituitary–thyroid axis, in which an increased concentration of thyroxine (T4) and triiodothyronine (T3) inhibits secretion of thyrotropin-releasing hormone (TRH) and thyrotropin (TSH). This mechanism helps maintain a stable internal environment, or homeostasis.
Understanding how hormones work is also important when choosing products for skin care and support. Hormonal changes can affect the skin's hydration, elasticity and sensitivity, as well as the rate at which it renews itself. Next, we will introduce LIBRATELLO'Oon JAM cream, its ingredients and how it works, and explain how local care can support the skin during periods of hormonal change. We will also introduce you to rituals and to how important they are for our central nervous system.
What Are Hormones? — Literature and Sources
The scientific literature on hormones is based on endocrinology — the study of endocrine glands. Key sources include Campbell & Jialal (StatPearls), Stárka & Dušková (Physiol Res 2020), and Norman & Henry (Hormones, 3rd ed.).
Campbell M, Jialal I. Physiology, Endocrine Hormones. StatPearls. PMID: 30860733.
https://pubmed.ncbi.nlm.nih.gov/30860733/
Stárka L, Dušková M. What Is a Hormone? Physiol Res. 2020. PMID: 33094616. DOI: 10.33549/physiolres.934509.
https://pubmed.ncbi.nlm.nih.gov/33094616/
Hiller-Sturmhöfel S, Bartke A. The Endocrine System: An Overview. PMID: 15706790.
https://pubmed.ncbi.nlm.nih.gov/15706790/
What Are Hormones and How Do They Support the Skin?
Hormones directly affect the skin — its moisture, elasticity and renewal. Hormonal changes during menopause or PMS cause dryness and a loss of elasticity. LIBRATELLO'Oon JAM cream is designed to support the skin during these periods.
Understanding how hormones work is key to a holistic approach to caring for the body. Hormonal changes directly affect the skin — its moisture, elasticity, renewal and sensitivity. This is why LIBRATELLO'Oon JAM cream for balance was created — the world's first holistic olfactory cosmetic product, supporting hormonal balance through scent and the transdermal route.
Ključna sestavina JAM kreme je divji jam (Dioscorea villosa), katerega bioaktivna spojina diosgenin je bila predmet številnih predkliničnih raziskav. Več o tem preberite v prispevku Wild Yam: Ingredients, Diosgenin and Hormonal Balance. Če vas zanima, kako hormonsko neravnovesje vpliva na vaše počutje, preberite tudi What Is a Hormonal Imbalance?.
Norman AW, Henry HL. Hormones. 3rd edition. Academic Press; 2015. Dostopno prek: NCBI Bookshelf.
Frequently Asked Questions About Hormones
What Are Hormones?
Hormoni so kemični prenašalci sporočil, ki usklajujejo delovanje skoraj vseh organov v telesu. So biološko aktivne signalne molekule, ki jih sintetizirajo endokrine žleze in jih izločajo neposredno v krvni obtok.
Which Hormones Are Most Important for Women?
For women, the most important hormones are oestrogen, progesterone, testosterone, thyroid hormones, cortisol and insulin. Together, these hormones regulate the menstrual cycle, fertility, mood, metabolism and energy.
How Do Hormones Affect the Skin?
Hormones directly affect the skin — its moisture, elasticity, renewal and sensitivity. This is why LIBRATELLO'Oon JAM cream was created — a pioneering olfactory cosmetic product designed to support the skin during periods of hormonal change.