a chemical transmitter substance produced by cells of the body and transported by the bloodstream to the cells and organs on which it has a specific regulatory effect. adj., adj
hormo´nal. Hormones act as chemical messengers to body organs, stimulating certain life processes and retarding others. Growth, reproduction, control of metabolic processes, sexual attributes, and even mental conditions and personality traits are dependent on hormones.
Hormones are produced by various organs and body tissues, but mainly by the endocrine glands
, such as the pituitary, thyroid, and gonads (testes and ovaries). Each gland apparently synthesizes several kinds of hormones; the adrenal glands alone produce more than 25 varieties. The total number of hormones is still unknown, but each has its unique function and its own chemical formula. After a hormone is discharged by its parent gland into the capillaries or the lymph, it may travel a circuitous path through the bloodstream to exert influence on cells, tissues, and organs (target organs) far removed from its site of origin.
One of the best-known endocrine hormones is insulin
, a protein manufactured by the beta cells of the islands of Langerhans in the pancreas that is important in carbohydrate metabolism. Other important hormones are thyroxine
, an iodine-carrying amino acid produced by the thyroid gland; cortisone
, a member of the steroid family from the adrenal glands; and the sex hormones, estrogen
from the ovaries and androgen
from the testes. Certain hormone substances can be synthesized in the laboratory for treatment of human disease. Animal hormones can also be used, as endocrine hormones are to some extent interchangeable among species. Extracts from the pancreas of cattle, for example, enabled diabetes sufferers to live normal lives even before the chemistry of insulin was fully understood.
Endocrine hormone synthesis and secretion is controlled and regulated by a closed-loop system. Negative feedback
loops maintain optimal levels of each hormone in the body. If there are abnormally high levels of a hormone in the blood, feedback to the gland responsible for its production inhibits secretion. If there are abnormally low levels, the gland is stimulated to step up production and secretion. In this way a homeostatic balance is maintained. (See also endocrine glands
adrenocortical hormone 1.
any of the corticosteroids secreted by the adrenal cortex
, the major ones being the glucocorticoids and mineralocorticoids, and including some androgens, progesterone, and estrogens.
(CRH) a neuropeptide secreted by the median eminence of the hypothalamus that binds to specific receptors on the corticotroph cells of the anterior pituitary and stimulates the secretion of corticotropin
ectopic h's those secreted by tumors of nonendocrine tissues but having the same physiologic effects as their normally produced counterparts. It is not known exactly how the synthesis and secretion of endocrine hormones from nonendocrine tissues occurs. Most of these tumors are derived from tissues that have a common embryonic origin with endocrine tissues. When the cells undergo neoplastic transformation, they can revert to a more primitive stage of development and begin to synthesize hormones.
Ectopic hormones present serious problems for patients and add to the complexity of caring for those with certain kinds of neoplastic diseases. These hormones do not respond to the feedback mechanisms that regulate normal hormonal production; hence, surgery and destruction of the tumorous tissue by radiation and chemotherapy are the treatments of choice.
(FSH) one of the gonadotropins
of the anterior pituitary, which stimulates the growth and maturity of graafian follicles in the ovary, and stimulates spermatogenesis in the male.
growth hormone–releasing hormone
(GH-RH) a neuropeptide elaborated by the median eminence of the hypothalamus that binds to specific receptors on the somatotroph cells of the anterior pituitary and stimulates the secretion of growth hormone
a substance with hormone like properties that acts at an anatomically restricted site; most are rapidly degraded. Called also autacoid
(LH) a gonadotropin
of the anterior pituitary gland, acting with follicle-stimulating hormone
to cause ovulation of mature follicles and secretion of estrogen by thecal and granulosa cells of the ovary; it is also concerned with corpus luteum formation. In the male, it stimulates development of the interstitial cells of the testes and their secretion of testosterone. Called also interstitial cell–stimulating hormone
(MSH) a substance from the anterior pituitary gland
of certain other animals but not humans; it influences the formation or deposition of melanin
in the body and pigmentation of the skin.
(PTH) a polypeptide hormone secreted by the parathyroid glands
that influences calcium and phosphorus metabolism and bone formation.
hormones secreted by the placenta, including chorionic gonadotropin
, and other substances having estrogenic, progestational, or adrenocorticoid activity.
2. progestational agent.
a hormone released by the hypothalamus
that inhibits the secretion of prolactin
by the anterior pituitary gland
(TRH) a tripeptide hormone of the hypothalamus, which stimulates release of thyrotropin
from the pituitary gland. In humans, it also acts as a prolactinreleasing factor
. It is used in the diagnosis of mild hyperthyroidism
and Graves disease, and in differentiating between primary, secondary, and tertiary hypothyroidism
A chemical substance, formed in one organ or part of the body and carried in the blood to another organ or part where they exert functional effects; depending on the specificity of their effects, hormones can alter the functional activity, and sometimes the structure, of just one organ or tissue or various numbers of them. Various hormones are formed by ductless glands, but molecules such as secretin, cholecystokinin/somatostatin, formed in the gastrointestinal tract, by definition are also hormones. The definition of hormone has been recently extended to chemical substances formed by cells and acting on neighboring cells (that is, paracrine function) or the same cells that produce them (that is, autocrine function). For hormones not listed below, see specific names.
[G. hormōn, pres. part. of hormaō, to rouse or set in motion]
hormone /hor·mone/ (hor´mōn) a chemical substance produced in the body which has a specific regulatory effect on the activity of certain cells or a certain organ or organs.hormo´nal
1. any of the corticosteroids elaborated by the adrenal cortex, the major ones being the glucocorticoids and mineralocorticoids, and including some androgens, progesterone, and perhaps estrogens.
adrenomedullary hormones substances secreted by the adrenal medulla, including epinephrine and norepinephrine.
(CRH) a neuropeptide elaborated mainly by the median eminence of the hypothalamus, but also by the pancreas and brain, that stimulates the secretion of corticotropin
ectopic hormone one released from a neoplasm or cells outside the usual source of the hormone.
eutopic hormone one released from its usual site or from a neoplasm of that tissue.
fibroblast growth hormone a peptide hormone secreted by the adenohypophysis that is a potent mitogen of vascular endothelial cells and a regulator of tissue vascularization.
(GH) any of several related hormones secreted by the adenohypophysis
that directly influence protein, carbohydrate, and lipid metabolism and control the rate of skeletal and visceral growth; used pharmaceutically as somatrem
hormones elaborated by one body structure that inhibit release of hormones from another structure; applied to substances of established clinical identity, while those whose chemical structure is still unknown are called inhibiting factors.
, lactogenic hormone prolactin
local hormone a substance with hormonelike properties that acts at an anatomically restricted site.
luteinizing hormone–releasing hormone
(LH-RH) a glycoprotein gonadotropic hormone
of the adenohypophysis
that acts with follicle-stimulating hormone
to promote ovulation and promotes secretion of androgen and progesterone. A preparation of the salts is used in the differential diagnosis of hypothalamic, pituitary, and gonadal dysfunction and in the treatment of some forms of infertility and hypogonadism.
melanocyte-stimulating hormone , melanophore-stimulating hormone (MSH) one of several peptides secreted by the anterior pituitary in humans and in the rhomboid fossa in lower vertebrates, influencing melanin formation and deposition in the body and causing color changes in the skin of amphibians, fishes, and reptiles.
parathyroid hormone a polypeptide hormone secreted by the parathyroid glands, which influences calcium and phosphorus metabolism and bone formation.
hormones elaborated in one structure that cause the release of hormones from another structure; applied to substances of established chemical identity, while those whose chemical structure is unknown are called releasing factors.
, somatotropic hormone growth h.
thyroid hormones thyroxine, calcitonin, and triiodothyronine; in the singular, thyroxine and/or triiodothyronine.
(TSH), thyrotropic hormone thyrotropin
a chemical transmitter substance produced by cells of the body and transported by the bloodstream and other means to the cells and organs which carry specific receptors for the hormone and on which it has a specific regulatory effect.
Hormones act as chemical messengers to body organs, stimulating certain life processes and retarding others. Growth, reproduction, control of metabolic processes, sexual attributes and behavior are dependent on hormones.
Hormones are produced by various organs and body tissues, but mainly by the endocrine
glands, such as the pituitary, thyroid and gonads (testes and ovaries). Each gland apparently manufactures several kinds of hormones; the adrenal glands alone produce more than 25 varieties. The total number of hormones is still unknown, but each has its unique function and structure. After a hormone is discharged by its parent gland into the capillaries or the lymph, it may travel a circuitous path through the bloodstream to exert influence on cells, tissues and organs (target organs) far removed from its site of origin.
substances secreted by the adrenal
medulla, including epinephrine and norepinephrine.
the masculinizing hormones, androstenedione and testosterone.
modern techniques include the use of competitive protein binding assay and radioimmunoassay.
any hormone which is specifically involved in the homeostatic regulation of serum calcium levels through their effects on bone and other organs, e.g. parathyroid hormone, calcitonin.
corpus luteum hormone
those secreted by tumors of nonendocrine tissues but having the same physiological effects as their normally produced counterparts. It is not known exactly how the synthesis and secretion of endocrine hormones from nonendocrine tissues occurs. Most of these tumors are derived from tissues that have a common embryonic origin with endocrine tissues. When the cells undergo neoplastic transformation, they can revert to a more primitive stage of development and begin to synthesize hormones.
hormone secreted by endocrine cells in the wall of the intestine or stomach or in the pancreas. Includes gastrin, cholecystokinin, secretin, gastric inhibitory polypeptide, enteroglucagon, motilin, neurotensin, 5-HT, substance P, pancreatic polypeptide, somatostatin.
substances capable of producing certain biological effects, the most characteristic of which are the changes which occur in mammals at estrus; the naturally occurring estrogenic hormones are β-estradiol, estrone and estriol.
steroids in birds which affect development of the reproductive tubular system, head decorations, feathers, squawk, behavior.
substances sprayed on plants which exert a lethal hormonal effect on the entire plant. See also hormone weedkiller (below).
lactation hormone, lactogenic hormone
luteotropic hormone (LTH) neurohypophyseal h's
those stored and released by the neurohypophysis, i.e. oxytocin and vasopressin.
peptide molecules which exert their effects only on target cells that carry the hormone-specific receptors.
one secreted by the placenta, including chorionic gonadotropin, relaxin, and other substances having estrogenic, progestational or adrenocorticoid activity. See also placental
substances, including progesterone
, that are concerned mainly with preparing the endometrium for nidation of the fertilized ovum if conception has occurred. See also progestational
the presence of hormone-specific receptors on cells is the means of determining which cells respond to the circulating hormones. The number of receptors on each cell is one of the ways of regulating the degree of response.
see follicle-stimulating hormone
, luteinizing hormone
somatotrophic hormone, somatotropic hormone
somatotropin release inhibiting hormone
somatotropin releasing hormone (SRH)
growth hormone releasing hormone.
includes 2,4-D, 2,4,5-T, MCP, silvex, dalapon. See also tcdd
Patient discussion about Hormone
Q. does the growth hormone have side effects and what are they?
A. Yes, it does, and not a few. They include, among others, pain in the joints, carpal tunnel syndrome, diabetes, pain at the injection site, problems with the thyroid gland, ear problems and many others. You may read more about side effects of growth hormone treatment (called Mecasermin or Somatropin) here: http://www.drugs.com/ppa/mecasermin.html
Q. what is the effect of hormones during pregnancy on a woman's temper?
A. Hormonal changes during pregnancy can indeedn cause mood changes, starting from anxiety or agitations to developing major clinical symptoms of depression. Pregnancy affects each woman differently.
Q. What types of hormonal changes caused by fibromyalgia? Fibromyalgia affects hormones because I feel pain in my back bone. What types of hormonal changes caused by fibromyalgia?
A. Have you ever checked your back pain with a doctor? It may or may not be due to fibromyalgia. Low serotonin levels, low growth hormone levels, and low levels of neuropeptide Y, a component of the feel-good hormone neurotransmitter norepinephrine have been associated with fibromyalgia. Elevated levels of substance P acts as a neurotransmitter and signals the body to experience pain. These pains have also been observed in the spinal cord of fibromyalgia patients.More discussions about Hormone