Final answer:
The epidermis is the outer skin layer consisting mainly of keratinocytes in multiple layers, including the stratum corneum. These cells undergo a renewal process starting from the stratum basale, leading to the shedding of the outermost cells.
Step-by-step explanation:
The Epidermis and Its Layers
The epidermis is the outermost layer of the skin, composed predominantly of keratinocytes, which contribute to the production of keratin. The epidermis serves as a barrier to the external environment, and it consists of several layers, including the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum, with the stratum lucidum present only in certain areas like the palms and soles. Each layer of the epidermis has its specific functions and contribution to skin renewal.
Renewal Process of the Epidermis
The process of renewal in the epidermis involves the continuous division of stem cells in the stratum basale, which give rise to new keratinocytes. These cells progressively move upwards, undergoing changes that result in keratin production and eventual cell death as they transition into the stratum corneum. This surface layer is then sloughed off, making way for new cells underneath, thus maintaining a dynamic balance.