8.4 Lesson 4: Skin Pigment

Melanin is produced in the epidermis by melanocytes
- melanocytes convert tyrosine to melanin
- UV in sunlight increases melanin production
- there is a similar number of melanocytes in everyone, but differing amounts of pigment are produced
Clinical observations
- freckles or liver spots = melanocytes in a patch
- albinism = inherited lack of tyrosinase; no pigment
- vitiligo = autoimmune loss of melanocytes in areas of the skin produces white patches
The wide variety of colors in skin is due to three pigments - melanin, carotene, and hemoglobin (in blood in capillaries) - in the dermis.
Carotene in dermis
- yellow-orange pigment (precursor of vitamin A)
- found in stratum corneum & dermis
Hemoglobin
- red, oxygen-carrying pigment in blood cells
- if other pigments are not present, epidermis is translucent so pinkness will be evident