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.
Many of the organs that produce hormones are controlled by other hormones. Aging also changes this process. For example, an endocrine tissue may produce less of its hormone than it did at a younger age, or it may produce the same amount at a slower rate.