A system of glands that produces and secretes hormones into the bloodstream; the endocrine system is used to communicate on a broad scale to the cells in the body.
The major chemical messenger of the endocrine system, hormones are produced, stored and secreted by glands; hormones either increase or decrease activity of the cells with which they interact.
A term used to describe hormones that create opposite effects of one another; an example would be insulin lowers blood glucose while glucagon elevates blood glucose.
When one hormone allows another hormone to have its full effect; an example would be thyroid hormones allowing growth hormone to have its full metabolic effects.
A term used to describe hormones that create similar effects through slightly different mechanisms; an example would be ADH stimulating kidneys to retain water while aldosterone stimulates kidneys to retain sodium, which in turn retains water.
The cell or group of cells with which a hormone is designed to interact.