examples being feet against shoes, even if the foot is covered by a sock.
In: 27
Friction blisters result from shearing forces (two forces going in opposite directions) where the epidermis (top layer of skin) is being pulled in a different direction than the underlying tissue. This can happen for example with ill-fitting shoes where the foot is moving forward but the skin on the foot is being pulled back at the point of friction. Moisture (either from sweating or getting wet) increases the friction and the chance of blister formation. Other factors in blister formation include the how strong the shearing force is and how many times it occurs.
What happens internally during blister formation is that this shearing force causes necrosis (cell death) in the weakest layer of the epidermis called the stratum spinosum. The cell death leads to a split in the middle of the epidermis which then fills with sterile fluid called serum. Serum comes from nearby blood vessels that are responding to the injury.
Interestingly, blisters tend to form in areas of the body that have a thick stratum spinosum layer – which would be feet and hands. In other areas of the body, shearing forces tend to form abrasions (scrapes) or ulcers instead.
Latest Answers