However, the red-yellow pheomelanin is believed to cause the warm, golden, or auburn tones found in some types of brown hair. The range of colors produced by melanins is limited to shades of yellow, brown, red, and black. Grey hairs contain only a few melanin granules, spread out through the hair.
Hormones are your body's chemical messengers. They travel in your bloodstream to tissues or organs. Endocrine glands, which are special groups of cells, make hormones. The major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal glands, and pancreas. In addition, men produce hormones in their testes and women produce them in their ovaries.
The hormone most often affected is called growth hormone, or GH. It is produced by the pituitary gland, a tiny organ at the base of the brain. Growth hormone promotes growth of bone, cartilage, muscle, organs, and other tissues. When there is too much growth hormone in the body, these tissues grow larger than normal. This excessive growth can cause serious disease and even premature death.