What is the epidermis primarily composed of?

The epidermis is primarily composed of a layer of dead cells, specifically keratinocytes that have undergone a process called keratinization. This outermost layer serves as a protective barrier against environmental hazards such as pathogens, ultraviolet radiation, and water loss. As cells in the lower levels of the epidermis divide and move upwards, they gradually lose their nuclei and cytoplasmic contents, becoming filled with keratin. This process creates a resilient and protective outer layer of dead, flattened cells that continuously shed and are replaced.

While there are living cells present in the epidermis, particularly in the deeper stratum layers, it is the outer layer that consists primarily of dead cells, which is crucial for maintaining skin integrity and resilience. Understanding the composition and function of the epidermis aids in comprehending how the skin protects the body and responds to injury and environmental challenges.