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.
Diseases and Conditions. Chronic diseases and other conditions may affect endocrine system function in several ways. After hormones produce their effects at their target organs, they are broken down (metabolized) into inactive molecules. The liver and kidneys are the main organs that break down hormones. The ability of the body to break down hormones may be decreased in people who have chronic heart, liver, or kidney disease. Abnormal endocrine function can result from: 1  congenital (birth) or genetic defects (see section on Genetics below).