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Nature's Messenger: Why are hormones the lifeline of multicellular organisms?
Hormones, derived from the Greek word "ὁρμῶν", meaning "to prompt action", are signaling molecules that play an extremely important role in multicellular organisms. Hormones are transported to distant organs or tissues through complex biological processes to regulate physiology and behavior. Hormones are indispensable for the correct development of animals, plants and fungi.
The broad definition of hormones allows a variety of molecules to be classified as hormones, including eicosanoids, steroids, amino acid derivatives, etc.
The main function of hormones is to affect remote cells by binding to specific receptors in target cells, thereby changing cell function. When hormones bind to receptors, they induce activation of signaling pathways, often promoting gene transcription, which in turn increases the expression of target proteins. In plant growth and development, hormones regulate almost all aspects from germination to senescence.
Hormones can transmit signals through cell membranes. Most water-soluble hormones act on the surface of target cells, while fat-soluble hormones can enter cells for regulation.
In vertebrates, endocrine glands are organs specialized in secreting hormones. Hormone secretion is usually in response to specific biochemical signals and is often affected by negative feedback regulation. For example, high blood sugar increases the synthesis of insulin, which lowers blood sugar levels. After hormone secretion, water-soluble hormones are rapidly transported through the circulatory system, while fat-soluble hormones need to be bound to carrier proteins to form complexes and be released into the circulatory system.
The discovery process of hormones
In the course of hormone research, many scientists have conducted in-depth discussions on its internal working mechanisms. For example, German physiologist Arnold Adolf Berthold conducted an experiment in 1849 that demonstrated the importance of testicles to male behavior. By observing castrated roosters, he discovered that there was a secreted substance that made them lose their male characteristics, which was later identified as testosterone.
Hormones not only play an important role in animals, but hormones in plants such as auxin are also critical, affecting the growth and direction of plants.
Emilio Baillis and Ernst Starling revealed in 1902 that intestinal secretions stimulate the pancreas to secrete digestive juices, which is considered the first hormone discovery. Over time, scientists have gradually discovered many other hormones that play an integral role in the life activities of multicellular organisms.
The mechanism of action of hormones
The effects of hormones depend on how they enter target cells and bind to receptors. Different types of hormones can act through receptors in the cell membrane or within the cell. Generally speaking, the binding of hormones to receptors initiates a series of signaling processes, triggering responses at the cellular level. These reactions can affect the metabolic activity, proliferation and growth of cells.
The binding of hormones to their receptors can lead to multiple changes within cells, thereby regulating the expression of target genes and protein synthesis.
In the human body, the functions of hormones include stimulating or inhibiting growth, regulating mood and metabolism, and preparing the body to enter a new stage of life such as puberty or menopause. Through these mechanisms, hormones provide a stable internal environment for the organism and help it maintain homeostasis in the changing external environment.
The relationship between hormones and behavior
On a behavioral level, hormone concentrations affect a person's mood and behavior. For example, the release of certain hormones is associated with mood swings. The behavior itself can in turn affect the release of hormones. This is a virtuous feedback loop, meaning there is a close interplay between behavior, environment and hormones.
This complex feedback mechanism is critical in many physiological processes, helping organisms adapt to internal and external stresses and changes.
When discussing the impact of hormones on life, one cannot help but think, are these biochemical messengers really the key to maintaining the functioning of organisms?
