Which feature best describes how the skin acts as a barrier to infection when intact?

Which feature best describes how the skin acts as a barrier to infection when intact?

• A. It forms a physical barrier with a soft outer layer
• B. It constantly produces antibodies on its surface
• C. It is impermeable to all pathogens regardless of injuries
• D. It forms a physical barrier with a tough outer layer; sebum production and an acidic environment help prevent entry when intact

Answer: (D)

Intact skin provides a dual defense: a tough physical barrier and chemical defenses. The outermost skin layer, the stratum corneum, is made of keratinized dead cells tightly packed together and coated with lipids, forming a hard, durable shield that’s hard for microbes to breach. On top of that physical barrier, sebaceous glands produce sebum and the skin surface remains acidic, with a pH around 5.5. This combination — a hard protective layer plus antimicrobial oils and an acidic environment — helps prevent entry of many pathogens when the skin is intact. So describing both the tough physical barrier and the chemical conditions that deter microbes captures how the skin stops infection under normal, uninjured conditions.

Intact skin provides a dual defense: a tough physical barrier and chemical defenses. The outermost skin layer, the stratum corneum, is made of keratinized dead cells tightly packed together and coated with lipids, forming a hard, durable shield that’s hard for microbes to breach. On top of that physical barrier, sebaceous glands produce sebum and the skin surface remains acidic, with a pH around 5.5. This combination — a hard protective layer plus antimicrobial oils and an acidic environment — helps prevent entry of many pathogens when the skin is intact. So describing both the tough physical barrier and the chemical conditions that deter microbes captures how the skin stops infection under normal, uninjured conditions.