Hormones are the chemical substances produced mainly by the endocrine glands and circulated through the blood stream. They act as the signaling molecules between cells and are used to communicate between organs and tissues to control the physiological and behavioural attributes of the various organs in the human body. Any imbalance in the production and distribution of the hormones leads to several medical conditions classified as endocrinal disorders that can have the following effects on the body.
Regulation of metabolism
Growth stimulation or inhibition
Activation or inhibition of the immune system
Wake-sleep cycle and other circadian rhythms
Preparation of the body for a new phase of like puberty,parenting and menopause
Preparation of the body for mating, fighting or other activities
Control of the reproductive cycle
Induction or suppression of programmed cell death (apoptosis)
Hormone secretion may also occur from tissues in other organs as well, in response to specific biochemical signals from other regulatory systems. A hormone may also regulate the production and release of other hormones. Hormone signals control the internal environment of the body through homeostasis.