How does skin function as a defence against disease?
20th April 1999 The skin provides an effective physical barrier between the external and internal environments. Whenever the skin surface is broken or compromised, pathogenic organisms can gain entry, multiply and spread. The skin consist of two main layers, an outer layer called the epidermis and an inner layer called the dermis. Deep to the dermis is the subcutaneous layer which is composed of adipose tissue. Glands and hair follicles dervived from the epidermis dip into the dermis. The epidermis is composed of stratified squamous epithelium and the dead outermost cells are constantly being shed. They contain a protein called keratin which provides waterproofing and protection against bacteria, chemical agents and minor degrees of trauma. Specialised cells called melanocytes are also situated in the epidermis. The melanocytes produce melanin and production is stimulated by both the action of the sun rays on the skin and melanocyte stimulating hormone produced by the anterior pituitar
