A regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action. It can also be defined as a chemical substance produced in the body that controls and regulated the activity of certain cells or organs.
Hormones are your body chemical messengers. They travel in your bloodstream to tissues or organs. They work slowly, over time, and affect many different processes, including, Growth and development, Metabolism, Sexual function, Reproduction, Mood.
Hormones are powerful. It takes only a tiny amount to cause big changes in cells or even your whole body. That is why too much or too little of a certain hormone can be serious. Laboratory tests can measure the hormone levels in your blood, urine, or saliva. Your health care provider may perform these tests if you have symptoms of a hormone disorder.