There are essentially four kinds of hormones in our bodies, and they are typed depending on what kind of molecule they are built from. Sexual hormones such as testosterone are built around a specific type of molecule, a sterol, from which the word steroid comes. You are familiar with the name of the particular sterol that is used for sexual hormones—cholesterol. It is, in fact, cholesterol from which all steroid hormones are made.
Adrenaline is another kind of hormone that serves as a source of energy during the flight-or-fight response. It is built around an amino acid called tyrosine (as is the thyroid hormone thyroxine) in the adrenal gland. Another type of hormone, insulin, which is highly important in the body’s ability to utilize glucose (a kind of sugar) effectively, is built in the pancreas using complex proteins. Others are built around short-chain amino acids called peptides.
Hormones regulate much of the functioning of our bodies. Through complex biofeedback loops, our bodies determine exactly what their needs are at any one moment in time and either make or release hormones to shift their functioning in the direction it needs to go. As an example of this kind of generalized biofeedback, there is no central thermostat in our bodies that keeps them at a certain temperature. Despite the famous 98.6° redlined on so many thermometers, the temperature of the body shifts constantly; it is always in flux.
The various systems of the body compare notes as it were and together, in some manner not understood by scientists, come to a conclusion about how temperature needs to shift and then shift it. We are more a collection of cooperating parts, each with its own innate intelligence, than a mechanical system with the brain acting as intelligent overseer. Our hormone levels are, as well, constantly in flux. Our bodies make and release hormones as we need them to remain vital and healthy. Part of this process includes the making and releasing of sexual hormones. In middle age, the amount of testosterone in male bodies naturally shifts, as does the balance between androgens and estrogens. It is the movement toward excess levels of estrogen and the over reduction of testosterone that produces a great many of the problems that men face as they age.