Library · Physiology
Skin barrier
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The skin, along with hair, nails and glands, makes up the integumentary system, the largest organ in the body. Its most obvious job is to act as a physical barrier between what is outside and what is inside, and to protect that interior.
As a barrier, the first thing it does is keep things out. Pathogens, meaning microbes capable of causing disease, do not get in directly because skin cells are joined to one another by junction proteins, and those junctions are reinforced by filaments of keratin, the tough protein that nails are also made of. A wall whose bricks are stitched to one another.
And there is a second layer of defense that you cannot see. On the skin there are antimicrobial peptides, small proteins that attack microbes, and lipids, that is, fats, stored inside the stratum corneum, the outermost layer of the epidermis. That biomolecular barrier breaks down bacterial membranes.
In brief
The integumentary system is the largest organ in the body and forms a physical barrier between the outside environment and the inside, which it protects and maintains.
As a barrier it blocks pathogens from entering directly: its cells are held together by junction proteins reinforced with keratin filaments.
A wall whose bricks are stitched to one another.
On top of that sits a biomolecular barrier: antimicrobial peptides on the skin and lipids stored in the stratum corneum, which break down bacterial membranes.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Integument, StatPearlsPublished
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