For healthy skin, collagen is key: This naturally occurring protein keeps skin smooth and youthful, but our bodies produce less collagen as we get older. The result? Thinner skin, dryness, and more wrinkles.
Definition of BLACK BILE. : a humor of medieval physiology believed to be secreted by the kidneys or spleen and to cause melancholy. ADVERTISEMENT.1681. a humor of medieval physiology believed to be secreted by the kidneys or spleen and to cause melancholy. ADVERTISEMENT. 1681.
Bilirubin, a brownish yellow pigment of bile, secreted by the liver in vertebrates, which gives to solid waste products (feces) their characteristic colour. It is produced in bone marrow cells and in the liver as the end product of red-blood-cell breakdown.