Why do epidermal cells die?

Answer 1

We skin cells are made, they are made in the deep layers of the skin, the dermal layer. This layer of the skin has blood supply, and cells that are in the dermal layer stay alive just fine. However, as cells in the upper layer, the epidermis, die; the skin cells in the dermal layer gets, pushed up into the epidermal layer. In this layer of the skin, there is no blood supply. However, nutrients are still passed from the blood rich dermal cells to the epidermal cells. The problem occurs when the epidermal cell is pushed right to the top of the epidermal layer, where there is no blood supply and it is too far away from the dermal layer to get nutrients vie osmosis. The cells in the upper epidermis get no nutrients and therefore die. Epidermal cells also die, ironically, because of the substances that they produce, keratin. Keratin is secreted by all skin cells to make the skin tough, durable and waterproof. However the build up of this keratin in the cell, leaks out in the extracellular space (the area outside the cell) and starts to breakdown the membranes of the cells around them and the cells essentially end up killing each other.

Epidermal cells die because of the loss of nutrient supply as they get closer and closer to the surface of the skin, and the buildup of keratin inside them that leaks out into the area outside the cells.