Hormones are remarkable biological chemicals which can act as messengers to get the target tissue to react in a specific way. A very small amount of a hormone can initiate changes in tissue and they are found in all biological organisms more complex than a single cell.
Hormones can be chemically quite simple molecules such as epinephrine, whereas others can be large and complex proteins such as insulin. Hormones have a specificity for particular target tissues which react to them because they have receptors which detect even very low levels.
When the receptor in the target tissue detects the hormone, it reacts in such a way as to cause changes in the surrounding tissue. In this way, a small amount of the hormone acts as a messenger to signal the need to change state.
Where do hormones come from?
Most cells in the body are able to produce molecules which can act as messengers to other tissues, but some organs of the body are more specialised and produce a range of such messenger molecules. The endocrine glands include the thyroids, the adrenal glands and the pituitary gland and these are specialised to produce specific hormones.
These are secreted into the bloodstream and circulate around the body. Because of their specificity, the hormones react only with the target tissues, providing a sophisticated messaging system for controlling metabolism.
The hormones are produced by specific biochemical pathways depending on their structure. Steroid hormones such as the corticosteroids are built up from cholesterol, whereas the simpler adrenaline is synthesised in the body from the amino acid tyrosine.
Hormone balance
Such a complex system of interrelated chemical messengers is maintained in balance by controlling the production of hormones. Inhibitors can prevent the production of certain hormones, or turn of its production. Other hormones can act as suppresant or stimulants, and even mental activity can lead to the release of hormones.
Hormones can be released in response to environmental changes, chemical changes in the body, or even the concentration of nutrients. So hormonal balance is no single entity, but a constant correction of changing levels of interrelated chemicals, with a vast number of control and feedback mechanisms. To speak of hormone balance is almost meaningless unless we are discussing a particular set of related hormones.
It is popular for alternative medicine practitioners to claim to balance hormones but this only demonstrates their naive approach.
Hormone disorders
The human body does not always work perfectly and occasionally there are disorders based on the inadequate supply or functioning of hormones. A common example is diabetes in which either insufficient insulin is produced (Type I) or the muscle tissues are inadequately sensitive to it (Type II). In such cases, treatment may require the substitution of the hormone.
Insulin can be injected into diabetics to make good the missing hormone reversing the symptoms of diabetes. Many other hormone related conditions can also be treated with hormone treatments. Hormones in the human body are delicately balanced which means that even minor imbalances can produce a wide range of symptoms.
Most of the hormones now have known chemical structures which means that they can be synthesised artificially and provided as pharmaceuticals. There are now very many hormonal disorders that can be effectively treated but there are still many complex conditions in which hormones play which are difficult to treat.
Changing the levels of hormones has knock-on effects and the complex system of interrelated balances is very delicate.
Hormone abuse
Since the hormones are powerful messengers acting on tissues, they can be use to bring about specific changes. One such use is in the field of body-building and athletics where performance enhancing steroids help competitors build up muscle mass.
Hormone use has been banned in international sport and there are detection mechanisms for many classes of hormones. Nevertheless, doping continues to be a problem. In addition, long term hormone abuse can have major consequences for health.
