Pigmentation of skin

Published on May 4, 2014   33 min
0:00
Hello, my name is Glynis Scott. I'm a professor of dermatology and pathology at the University of Rochester. This talk will be on pigmentation of skin and will focus primarily on pigmentation of human skin.
0:16
In this talk I'm going to cover five main areas. I'm first going to discuss melanin, its basic molecular nature and its secondary structure. I'm then going to discuss tyrosinase, which is the enzyme that catalyzes the rate-limiting step in melanin synthesis and discuss, in some detail, how tyrosinase is regulated. In the third part of the talk, I'm going to discuss melanocytes, which are the cells that produce melanin. And I'm going to go over melanosomes, which are subcellular organelles within melanocytes in which melanin is synthesized. In the fourth part of the talk, I'm going to discuss the process of tanning, which is the response of the skin to ultraviolet irradiation. And finally, in the last part of the talk, I'm going to discuss the evolutionary pressures that have led to the distinctive patterns of skin pigmentation across the globe.
1:12
Before we get started, I wanted to do a brief review of the architecture of the skin. The skin has three main layers, the epidermis, the dermis, and the subcutis. And the pigmentation of the skin is almost exclusively performed by the most superficial layer of skin, which is the epidermis, which is the topmost layer. The epidermis is composed of, predominantly, keratinocytes, which are the majority component, and a minority component of cells, called the melanocytes, which are the pigment-producing cells. The pigmentation of the skin-- one of its main functions is to protect not only keratinoctyes from phototoxic damage and carcinogenic damage, but to protect the underlying dermis, which is directly beneath the epidermis. And then the other underlying structures of the skin are really not much affected by ultraviolet irradiation because they are too deep.