The "Barrier Function" refers to the ability of a biological membrane, such as the skin or intestinal lining, to protect the body from harmful substances and pathogens. This function is crucial for maintaining homeostasis, as it regulates the passage of water, nutrients, and waste products while preventing the entry of toxins and microbes. In the context of skin, the barrier function is primarily provided by the outermost layer, known as the stratum corneum. This layer consists of dead skin cells and lipids that create a protective shield. A compromised barrier can lead to conditions like eczema or increased susceptibility to infections.