• Question: Why do we have skin and why does it heal and how does it protect us?

    Asked by jennis123 to Alastair, Emma, Hywel, Keith, Vicki on 16 Jun 2010 in Categories: .
    • Photo: Alastair Sloan

      Alastair Sloan answered on 16 Jun 2010:

      Hi

      We have skin to protect our bodies and cover the specialist and delicate organs. It protects us by providing a waterproof covering over the body keep the inside sterile and preventing bacteria and other microorganisms getting inside us. It heals by remodelling. If we cut ourselves, we rapidly cover the hole to prevent anything getting it. The new cells are recruited to the area of the cut and make some new proteins which get woven around the site of the cut. The damaged blood vessels are reformed and the outer layer (called the dermis) becomes harder. The original plug which covered the hole is called the scab, and that will fall off once the skin underneath is fully reformed.

    • Photo: Keith Brain

      Keith Brain answered on 16 Jun 2010:

      We have skin, as you suggest, for protection! It’s difficult for water to cross the skin, which is important to ensure that we don’t dry up and to keep the right balance between salt and water in our skin (our body fluids are very salty, as you might know if you’ve managed to suck your own blood!). Skin is also tough – the outer layers are made of dead, compressed and matted skin cells, which gives it strength so that the odd scrape here and there doesn’t damage living tissue. It also helps us to retain heat (because is is relatively dry and doesn’t have a circulation in the outer (dead) layers, which is important when the outside temperature is cooler than body temperature (which is most of the time). It also provides a physical barrier against microorganisms.

      Regarding healing, it depends on the type of injury, but for a clean cut, the cells at the base of the skin multiply and slide sideways to cover the wound. Many cells circulating in the blood stream flood in to fight against the microorganisms that inevitably invade wounds. Cells called fibroblasts are important for creating fibrous tissue (collagen) that makes wounds strong, and are also important for helping to pull the wound edges together (so that there is less of a gap to bridge with new cells). There is an ingrowth of new blood vessels locally to help the defensive cells and provide the nutrients required for new cells to grow. Slowly (over days) the new skin growth from below, gradually building strength over weeks. So, a complex process, with complex control!

Comments