Growth hormone is also called somatotropin. It's a protein hormone of 190 amino acids (building blocks of protein) that is created and secreted by the anterior pituitary gland. It has two types of effects, both of which are highly beneficial to the vital, active human body as you'll see below.
One main type of action of the HGH is its direct effects on other kinds of cells. The growth hormone binds to its receptor on target cells, then creates some particular action. Fat cells, for example, are the target cells of HGH, so they have growth hormone receptors. Once bonded there, the growth hormone causes them to break down triglyceride and suppresses their ability to take up and accumulate circulating lipids -- in other words, fat storage is prevented!
HGH also acts to create other indirect effects in the body by causing secretion of IGF-1, an insulin-like growth factor hormone. IGF-1 is secreted from the liver and other tissues in response to growth hormone. This is the action that governs mostly growth-related effects of HGH.
Because of the abilities of HGH, you can soon see that without it, muscle tone declines, fat stubbornly sits in the body and resists metabolism, and hair, skin and nails (all composed of proteins) deteriorate. In fact, scientists now believe that HGH has a role in most healthy functions of the body, including sexual function, proper operation of stomach and bowels, liver, and all glandular systems.
Whether HGH is directly interacting with certain cells, or playing its key part in the correct function of other bodily systems, it's essential throughout the body for youthful vigor and health!