The epidermis is nourished by diffusion from capillaries in the dermis. The dermis is the layer of skin located beneath the epidermis. It contains blood vessels, lymphatic vessels, hair follicles, and sweat glands. The capillaries in the dermis provide nutrients and oxygen to the cells of the epidermis through a process called diffusion. Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. In this case, nutrients and oxygen move from the capillaries in the dermis to the cells of the epidermis, which have a lower concentration of these substances.
The epidermis is the outermost layer of skin and serves as a protective barrier against environmental factors such as UV radiation, chemicals, and pathogens. It is composed of several layers of cells, including keratinocytes, melanocytes, and Langerhans cells. These cells are constantly being replaced by new cells that are produced in the basal layer of the epidermis.
In addition to providing nutrients and oxygen to the cells of the epidermis, the capillaries in the dermis also play a role in regulating body temperature. When body temperature rises, blood vessels in the dermis dilate, allowing more blood to flow to the skin's surface. This increases heat loss through radiation and convection. Conversely, when body temperature drops, blood vessels in the dermis constrict, reducing blood flow to the skin's surface and conserving heat.