- Key People:
- Tadeus Reichstein
- Gregory Pincus
- Related Topics:
- Hormone
- Steroid
- Sex hormone
- ecdysone
- adrenal hormone
Steroid hormone
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What is a steroid hormone?
Steroid hormones are a group of hormones derived from cholesterol and secreted by the adrenal cortex, testes, ovaries, and placenta.
These hormones, including androgens, estrogens, glucocorticoids, and mineralocorticoids, are transported through the bloodstream to target organs, where they regulate diverse physiological functions.
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What are some examples of steroid hormones in the human body?
Steroid hormones, derived from cholesterol, are secreted by the adrenal cortex, testes, ovaries, and placenta during pregnancy.
Key examples include:
* Androgens Primarily testosterone, responsible for male reproductive function and secondary sex characteristics.
* Estrogens (e.g., estradiol) Promote female sex characteristics and stimulate linear growth and skeletal maturation.
* Progestins (e.g., progesterone) Maintain pregnancy by preparing the uterine lining for implantation.
* Glucocorticoids (e.g., cortisol) Influence metabolic processes and help maintain blood pressure.
* Mineralocorticoids (e.g., aldosterone) Maintain water and salt balance in the body.6 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Where in the body are steroid hormones made?
Steroid hormones are synthesized and secreted in the adrenal cortex, ovaries, and testes. These hormones are derived from cholesterol and are transported through the bloodstream to target organs to regulate various physiological functions.
The adrenal cortex produces hormones such as glucocorticoids and mineralocorticoids. The testes produce androgens, like testosterone, while the ovaries produce estrogens and progestins. During pregnancy, the placenta also secretes steroid hormones.
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How do steroid hormones travel through the body?
Steroid hormones, a class of lipid molecules derived from cholesterol, act as chemical messengers in the body. They are transported through the circulation singly, bound to specific carrier proteins that target them to cells in particular organs. These transport proteins, produced by the liver, bind to specific hormones in the serum. Examples include sex hormone-binding globulin, which binds estrogens and androgens, and corticosteroid-binding globulin, which binds cortisol. Once a steroid hormone reaches its target cell and permeates the external membrane, it interacts with a specific carrier protein in the cytoplasm. This complex then migrates into the cell nucleus, where it interacts with DNA to either activate or repress transcription, which is the first step in protein biosynthesis.
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What do steroid hormones do in the body?
Steroid hormones, derived from cholesterol, are synthesized and secreted by the adrenal cortex, testes, and ovaries. During pregnancy, the placenta also secretes them. Once released, these hormones travel through the bloodstream to target organs, where they regulate diverse physiological functions.
Steroid hormones include androgens (male sex hormones), estrogens and progestins (female sex hormones), glucocorticoids, and mineralocorticoids. They influence reproductive function, sexual characteristics, metabolism, blood pressure, and the balance of water and salts in the body.
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How do steroid hormones affect cells to trigger changes in the body?
Steroid hormones, derived from cholesterol, affect cells by influencing gene expression. These hormones are produced in endocrine tissues and include progestins, glucocorticoids, mineralocorticoids, androgens, and estrogens.
Steroid hormones bind to carrier proteins, which transport them to target cells in specific organs. After penetrating the cell membrane, the steroid hormone interacts with a receptor protein in the cytoplasm, and the resulting complex migrates to the cell nucleus. There, it interacts with DNA to either activate or repress transcription, which is the first step of protein biosynthesis. This alters the rate at which certain proteins are synthesized.
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Steroid hormone, any of a group of hormones that belong to the class of chemical compounds known as steroids; they are secreted by three āsteroid glandsāāthe adrenal cortex, testes, and ovariesāand during pregnancy by the placenta. All steroid hormones are derived from cholesterol. They are transported through the bloodstream to the cells of various target organs where they carry out the regulation of a wide range of physiological functions.
These hormones often are classified according to the organs that synthesize them: the adrenal steroids are so called because they are secreted by the adrenal cortex, and the sex hormones are those produced by the ovaries and testes. This distinction is not exclusive, however, because the adrenal cortex also secretes sex hormones, albeit to a lesser extent than do the gonads, and the ovaries under abnormal conditions may produce adrenal steroids.
The adrenal cortex produces the adrenocortical hormones, which consist of the glucocorticoids and the mineralocorticoids. Glucocorticoids such as cortisol control or influence many metabolic processes, including the formation of glucose from amino acids and fatty acids and the deposition of glycogen in the liver. Glucocorticoids also help to maintain normal blood pressure, and their anti-inflammatory and immunosuppressive actions have rendered them useful in treating rheumatoid arthritis and preventing the rejection of transplanted organs. Mineralocorticoids such as aldosterone help maintain the balance between water and salts in the body, predominantly exerting their effects within the kidney.
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The androgens are the male sex hormones. The principal androgen, testosterone, is produced primarily by the testes and in lesser amounts by the adrenal cortex and (in women) by the ovaries. Androgens are primarily responsible for the development and maintenance of reproductive function and stimulation of the secondary sex characteristics in the male. Androgens also have an anabolic (synthesizing and constructive, rather than degradative) function in stimulating the production of skeletal muscles and bone as well as red blood cells. To enhance the anabolic activity of androgens without increasing their masculinizing ability, anabolic steroids were developed. Though originally intended to combat diseases marked by wasting, these synthetic hormones have been abused by individuals desiring to increase their muscle mass, such as athletes seeking to gain a competitive advantage. Overdosing has been linked to serious side effects, including infertility and coronary heart disease.
Estrogens are one of the two types of female sex hormones. They are secreted mainly by the ovaries and in smaller amounts by the adrenal glands and (in men) by the testes. Estradiol is the most potent of the estrogens. Functioning similarly to androgens, the estrogens promote the development of the primary and secondary female sex characteristics; they also stimulate linear growth and skeletal maturation. In other mammals these hormones have been shown to precipitate estrus (heat). The ovarian production of estrogen plummets during menopause.
Progestins, the most important of which is progesterone, are the other type of female sex hormone and are named for their role in maintaining pregnancy (pro-gestation). Estrogens and progestins are secreted cyclically during menstruation. During the menstrual cycle, the ruptured ovarian follicle (the corpus luteum) of the ovary produces progesterone, which renders the uterine lining receptive to the implantation of a fertilized ovum. Should this occur, the placenta becomes the main source of progesterone, without which the pregnancy would terminate. As pregnancy progresses, placental production of progesterone increases, and these high doses suppress ovulation, preventing a second conception. The contraceptive quality of progesterone led to the development of structurally modified progestins and estrogensāthe oral contraceptives known as birth-control pills, used by women to prevent unwanted pregnancy.