Skin Anatomy:
The skin is the largest organ of the human body. It covers the entire external surface of the human body and is the principal site of interaction with the surrounding world. Anatomically, there are three layers of skin - the epidermis, dermis, and subcutaneous tissue.
There are three types of specialized cells in the epidermis: the melanocyte produces pigment (melanin); the Langerhans' cell is the frontline defense of the immune system in the skin; and the Merkel's cell's function is not clearly known. The dermis is composed of different proteins: collagen, fibronectin, elastin and laminin (i.e. dermal extracellular matrix ECM). The subcutaneous tissue is a layer of fat and connective tissue that houses larger blood vessels and nerves. This layer is important is the regulation of temperature of the skin itself and the body.
Functions and Physiology:
The skin is an ever-changing organ, and the speed of skin aging can be attributed to various causes, including genetics, environmental damage, hormonal alterations, and metabolic processes. The skin’s structural integrity is maintained by dermal ECM proteins, especially collagen. Natural skin aging is usually characterized by decreased fibroblast activity, diminished production and increased degradation of dermal ECM proteins, which ultimately leads to skin laxity and wrinkles.
Skin Delivery:
Transdermal delivery of biologically active peptides can be achieved by modifying the pH, hydrophobicity/hydrophilicity, polarity, and encapsulation. 
Disclaimer
Information on this website is summarized from published literatures for education purpose only. All molecular structures listed are for example purposes but not meant to be used as ingredients in cosmetic products.
For regulatory policy of each molecule and its use for cosmetic product, please refer to the released information of FDA or your local government. All information is provided for informational and marketing purposes only.