The Protective Layer Of The Skin Essay
It has several functions, the most important being to form a physical barrier to the environment, allowing and limiting the inward and outward passage of water, electrolytes and various substances while providing protection against micro-organisms, ultraviolet radiation, toxic agents and mechanical insults. There are three structural layers to the skin: the epidermis, the dermis, and hypodermis (subcutaneous fat) . I will be discussing on epidermis that is the protective layer of the skin. This is a keratinized stratified squamous epithelium. That is, its surface consists of dead cells packed with the tough protein keratin. Like other epithelia, the epidermis lack blood vessels and depends on the diffusion of nutrients from the underlying connective tissue.(Saladin, 2015, pg178)
In vertebrates, it is made up of many layers of cells and overlies the dermis hair feathers grow from the epidermis. The thickness of the epidermis varies in different types of skin; it is only .05 mm thick on the eyelids, and is 1.5 mm thick on the palms and the soles of the feet.
Five types of cells make up the epidermis: