Human growth hormone, molecular model. Human growth hormone (hGH) is a hormone produced in the anterior pituitary gland in the brain. It binds to specific receptors on cells in the body to stimulate growth, especially in childhood. As well as that role, it is involved in strengthening bone, increasing muscle mass, reducing glucose uptake by the liver and promoting the breakdown of body fat (adipose tissue). Excess hGH in childhood can result in gigantism, while deficiency causes growth failure. In adults, deficiency causes weakness, lack of energy and weakened bones. In this model, the primary atomic structure is seen faintly behind the secondary structure of alpha helices (spirals) and beta sheets (flat arrows).