Skip to main content Skip to Search Box
Definition: hormone from Merriam-Webster's Collegiate(R) Dictionary

pronunciationpronunciation

(1905) 1 : a product of living cells that circulates in body fluids (as blood) or sap and produces a specific often stimulatory effect on the activity of cells usu. remote from its point of origin; also : a synthetic substance that acts like a hormone 2 : sex hormone

hor•mone•like \-॑līk\ adj

hormone

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
In biology, a chemical secretion of the ductless endocrine glands and specialized nerve cells (see neurohormones ) concerned with control of body functions. Hormones act as chemical messengers and are transported to all parts of the body by the bloodstream where they affect target organs. The major glands are the thyroid, parathyroid, pituitary, adrenal, pancreas, ovary, and testis. There are also hormone-secreting cells in the kidney, liver, gastrointestinal tract, thymus (in the neck), pineal (in the brain), and placenta. Hormones bring about changes in the functions of various organs according to the body's requirements. The hypothalamus , which adjoins the pituitary gland at the base of the brain, is a control centre for overall coordination of hormone secretion; the thyroid hormones determine the rate of general body chemistry; the adrenal hormones prepare the organism during stress for ‘fight or flight’; and the sexual hormones such as oestrogen and testosterone govern…
9,207 results

Full text Article hormone

From Philip's Encyclopedia
Chemical substance secreted by living cells. Hormones affect the metabolic activities of cells in other parts of the body. In mammals , glands of the endocrine system secrete hormones directly into the bloodstream. Hormones exercise chemical control of physiological functions, regulating growth, …
| 141 words
Key concepts:

Full text Article Hormones

From Gale Encyclopedia of Psychology
Hormones are natural chemical substances that transmit messages between organs and systems in the body that affect various systems and functions. Hormones are chemical messengers that help control physiological events in living organisms, including human bodies. More than 100 hormones have been…
| 2,154 words
Key concepts:

Full text Article Hormones

From Black's Veterinary Dictionary
Hormones are substances which upon absorption into the bloodstream influence the action of tissues or organs other than those in which they were produced. The internal secretions of the ovary, testicles, thyroid, parathyroid, adrenal, pituitary body, and the pancreas are examples of hormones. (See…
| 676 words
Key concepts:

Full text Article hormone

From Library of Health and Living: The Encyclopedia of Nutrition and Good Health
A chemical messenger sent through the bloodstream to target tissues. The name hormone is derived from the Greek word hormon , which means “to set in motion.” The brain and nervous system control hormone release from specialized tissues called endocrine glands, and the endocrine system consists of…
| 806 words
Key concepts:

Full text Article hormone

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
In biology, a chemical secretion of the ductless endocrine glands and specialized nerve cells (see neurohormones ) concerned with control of body functions. Hormones act as chemical messengers and are transported to all parts of the body by the bloodstream where they affect target organs. The major…
| 2,011 words
Key concepts:

Full text Article hormone ‡

From Cambridge Dictionary of Human Biology and Evolution
Any chemical substance produced in the body by an organ , by cells of an organ, or by scattered cells, and which has a specific regulatory effect on the activity of a certain organ or of certain cell types. Originally applied to substances secreted by various endocrine glands and transported in the…
| 203 words
Key concepts:

Full text Article hormone

From The American Heritage Student Science Dictionary
A substance produced in one part of the body, especially in an endocrine gland, that has an effect on another part of the body, to which it is usually carried in the bloodstream. Hormones regulate many biological processes, including growth and metabolism. hormones On the inside, humans are bathing…
| 172 words
Key concepts:

Full text Article hormone

From The Columbia Encyclopedia
secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue. Normally, various hormones are produced and secreted by the endocrine glands (see endocrine system ), …
| 392 words
Key concepts:

Full text Article hormones

From Collins Dictionary of Medicine
A term whose definition has expanded progressively over time with the growth of physiology. Chemical substances produced by the ENDOCRINE and other glands or cells and released into the bloodstream to act upon specific receptor sites in other parts of the body, so as to bring about various effects. …
| 167 words

Full text Article hormone

From Penguin Dictionary of Biology
Term once applied in both botanical and zoological contexts, but now restricted to the latter (see GROWTH SUBSTANCE ). Denotes any molecule, usually of small molecular mass, secreted directly into the blood by ductless glands and carried to specific target cells/organs by whose response they bring…
| 201 words
Key concepts:
Mind Map

Stack overflow
More Library Resources