What role does the skin play in the body’s defence against pathogens?
What role does the skin play in the body’s defence against pathogens?
Answer
The skin plays a crucial role in the body’s defense against pathogens, serving as the first line of protection through various mechanisms.
Physical Barrier
The skin acts as a physical barrier that prevents pathogens from entering the body. Composed of multiple layers, primarily the epidermis, it effectively blocks many external threats. The outermost layer, known as the stratum corneum, is particularly important as it is tough and minimizes water loss while also limiting microbial invasion due to its low moisture content and acidic pH.
Chemical Defenses
In addition to its physical properties, the skin also employs chemical defenses. It secretes substances such as sweat and sebum. Sweat contains salt and antimicrobial peptides that create an inhospitable environment for many microbes. Sebum, produced by sebaceous glands, has antibacterial and antifungal properties that further inhibit pathogen growth.
Immune Response
The skin is not just a passive barrier; it actively participates in immune defense through its resident immune cells. Keratinocytes, which make up the majority of the epidermis, play a key role by expressing Toll-like receptors (TLRs) that detect pathogens and trigger inflammatory responses. This immediate response is part of the innate immune system, which acts quickly to contain infections.Additionally, other immune cells such as Langerhans cells and macrophages are present in the skin. These cells can recognize and respond to foreign invaders by initiating phagocytosis—engulfing and destroying pathogens. The skin’s immune system also includes a network of lymphatic vessels that facilitate communication between skin-resident immune cells and those in the bloodstream, enhancing the body’s overall immune response
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