Hormones are chemical signaling molecules that coordinate bodily functions by carrying messages through the blood to organs, skin, muscles and other tissues, according to the Cleveland Clinic. These chemicals, which are essential for life and health, regulate physiology and behavior in multicellular organisms, including animals, plants and fungi, as reported by Wikipedia.
How do hormones regulate the body?
Hormones act as chemical messengers that manage hundreds of bodily processes, often through chain reactions involving multiple hormones, according to the Cleveland Clinic. A hormone only affects a specific part of the body if the cells in the target tissue have receptors that "fit" the hormone, similar to a key fitting into a lock.
Wikipedia reports that when a hormone binds to these receptor proteins, it typically activates a signal transduction pathway that increases the expression of target proteins by activating gene transcription.
- Between endocrine glands: One gland releases a hormone that stimulates another gland to change its own hormone levels. An example is the pituitary gland releasing thyroid-stimulating hormone (TSH) to trigger the thyroid gland.
- Between a gland and a target organ: The pancreas releases insulin, which then acts on the liver and muscles to help process glucose.
Which bodily processes do hormones control?
In vertebrates, hormones regulate a wide range of physiological and behavioral activities. According to Wikipedia, these include respiration, digestion, metabolism, excretion, lactation, stress induction, movement, sleep, and sensory perception.
- Mood and the sleep-wake cycle.
- Growth, development, and reproduction.
- Sexual function.
- Homeostasis, which includes the regulation of blood sugar, blood pressure, body temperature, and electrolyte and fluid balance.
Because these chemicals are potent, the Cleveland Clinic notes that minor changes in hormone levels can cause significant bodily changes and lead to conditions requiring medical treatment.
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What types of hormones exist?
Scientists have identified over 50 hormones in the human body so far, according to the Cleveland Clinic.
- Steroids: Including oestrogen and brassinosteroids.
- Proteins or peptides: Including insulin and CLE peptides.
- Amino acid derivatives: Including auxin and epinephrine.
- Eicosanoids: Including thromboxanes and prostaglandins.
- Gases: Including nitric oxide and ethylene.
The method of delivery depends on the hormone’s solubility. Wikipedia states that water-soluble hormones, such as amines and peptides, generally act on the surface of target cells via second messengers. Lipid-soluble hormones, such as steroids, typically pass through the plasma membrane to act within the nuclei. Brassinosteroids are a specific class of plant hormones that are lipid-soluble but still attach to receptors at the cell surface.
Where are hormones produced?
Most hormones are created and released by specialized glands that form the endocrine system, according to the Cleveland Clinic. These endocrine glands release hormones directly into the bloodstream.
Wikipedia notes that hormone secretion in vertebrates occurs in response to specific biochemical signals and is often managed by negative feedback regulation. For example, high blood sugar promotes the synthesis of insulin; once insulin reduces glucose levels to maintain homeostasis, insulin levels subsequently decrease.
While the endocrine system is the primary source, the Cleveland Clinic states that not all tissues that release hormones or hormone-like substances are considered part of the endocrine system.
Consult your healthcare provider for medical concerns or treatment options.
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