Skin Cell Types

The skin is the largest organ of the human body, providing protection from foreign bodies such as chemicals, microorganisms and sunlight. Alongside providing a protective layer topped by a layer of cells called the epidermis, the skin controls the temperature of the body and allows human beings the sense of touch.

Layers

• The skin is divided into three layers: the epidermis, dermis and subcutaneous layer. The epidermis is the layer of skin responsible for the production and use of cells that make their way to the surface of the skin. The epidermis is divided into four layers through which skin cells, or keratinocytes, move beginning in the basal layer and moving through the spinous and granular cell layers before arriving at the top layer called the stratum corneum. The skin is continually replenishing itself in the basal layer and shedding cells from the stratum corneum.

Basal

• The basal layer of cells is the breeding ground for new cells that are constantly formed by dividing cells to form new ones. The blood supply for the formation of new cells is provided in the dermis layer below the epidermis, where blood vessels supply nutrients to simulate cell growth within the basal cell layer. The division of new cells in the basal layer forces already formed cells upward toward the surface of the skin.

Movement

• As skin cells from the basal layer are pushed upward by the formation of new cells, they move away from the blood supply of the dermis layer and alter in shape and quality. After leaving the basal cell layer, skin cells enter the spinous cell layer where they are compressed into complex shapes as they make their way toward the surface. After leaving the spinous layer, cells enter the granular layer where they begin to die as they are starved of blood and nutrients. Within the granular cell layer skin cells begin to flatten in shape as they move upward.

Stratum Corneum

• The final stage of the journey of skin cells to the surface of the skin is the movement from the granular cell layer to the stratum corneum, which is the top layer of the skin made up of dead skin cells that form the tough, waterproof layer on the skin surface. As the cells from the lower layers of the skin make their way to the surface, dead skin cells are continually shed from the stratum corneum. The flattened cells on the surface layer form ridges that make up the individual fingerprints of each person.