Final answer:
Trans epidermal water loss is primarily prevented by the stratum corneum, with lipids forming a watertight barrier. Proteins like eleiden in the stratum lucidum and the acidic nature of the skin provide additional TEWL protection. In plants, a cuticle layer serves a similar protective function against water loss.
Step-by-step explanation:
Causes and Prevention of Trans Epidermal Water Loss
Trans epidermal water loss (TEWL) is the loss of water that passes from inside a living body through the epidermal layer and evaporates into the environment. The primary protective barrier against TEWL is the stratum corneum, which is composed of dead skin cells and lipids. These lipids are crucial as they form an organized barrier that is virtually watertight. A specialized protein-bound lipid known as eleiden, found in the stratum lucidum, also helps to prevent water loss by binding to keratohyalin.
In addition to the stratum corneum, other defensive mechanisms such as the acidic nature of the skin, low amounts of water, antimicrobial substances, and phagocytic Langerhans cells contribute to the protection against pathogens and thus indirectly prevent water loss by maintaining the integrity of the skin.
Moreover, another layer known as the cuticle covers the leaves of all plant species and reduces the rate of water loss from transpiration. While this context is better associated with plants, it illustrates a similar biological concept of protecting organisms from excessive water loss.