How do the integumentary structures contribute to the innate immune response in animals?

The integumentary system, which includes skin, hair, nails, and glands, serves as the body’s first line of defense by forming a physical barrier that blocks microbes from entering the body. Skin cells produce acids and antimicrobial peptides that directly kill or inhibit bacteria and fungi, while sweat and oil help maintain a hostile environment for pathogens. Specialized cells in the skin, such as Langerhans cells, constantly patrol for foreign invaders and can trigger inflammation to recruit other immune cells. When a cut occurs, the skin releases signals that attract white blood cells to the wound, speeding up repair and preventing infection. For example, a small scratch on the hand releases cytokines that attract neutrophils, which quickly destroy any invading bacteria before they can spread.