Skin and Wound

Skin is the body's first barrier, and it has three layers. The epidermis forms the barrier that keeps outside antigens and other substances from passing through, and it also contributes to immune defence and to fighting infection. The dermis lies beneath it and is the main interface with the skin's blood vessels and nerves, so it supplies nutrition and cutaneous sensation. The hypodermis (subcutaneous tissue) is the deepest layer and holds proportionally more fat cells and less collagen than the layers above. This anatomy explains what the nurse sees: a problem in the epidermis alone leaves the barrier compromised, loss into the dermis exposes a wound bed that is painful and richly supplied, and loss that reaches the hypodermis or deeper is a full-thickness injury. With ageing, epidermal turnover slows; a 2026 review of skin ageing (Biology) reports a fall of about 30 to 50% between the third and eighth decades of life, which is one reason older adults heal more slowly. Why pressure matters. A pressure injury is localized damage to the skin and/or underlying tissue from pressure, or...