How does hurt skin repair itself?

February 17, 2020 / Duncan Fisher
The 4 stages of wound healing

Did you hurt yourself? Ouch! We’re sorry.

You’ll get better, of course, as you know, because like us all, you’ve had plenty of cuts and scrapes in the course of your life.

Remember watching your little injuries get better when you were a kid? Do you remember how well you were able to predict the time they’d take to heal? You’d seen so many schoolyard scrapes scab over, puff up, and resolve that you got a pretty good sense of how skin fixes itself. You didn’t know it, but you were watching four distinct phases in tissue repair, that are very orderly and pretty remarkable, each of them.

Now that you’re grown up, you might be interested in knowing what was actually happening. The physiology of wound repair is surprisingly complex, and it’s fascinating when you understand it.

Here are the rudiments of what goes on.

The 4 phases of skin wound healing

Phase 1: Hemostasis

First, you bleed. But your blood, to say this strangely, kind of knows what to do. Platelets in the area come together with collagen, and ‘activate’, or change the nature of their outside surfaces, so that they start to stick together. That’s ‘coagulation’, and you see it happening within minutes. An enzyme in your blood plasma, called ‘thrombin’, starts converting a circulating protein called ‘fibrinogen’ into little fibers. These form a mesh at the wound site for those sticky platelets, and presto, you’re forming a clot, to stop that blood loss. This is ‘hemostasis’, a word that derives from two Greek words, that mean ‘blood’ and ‘halting’.

Phase 2: Inflammation

Then you hurt. That’s because you’re puffing up. It’ll go for a few days, thereabouts. This inflammatory stage is when swarms of ‘neutrophils’, a kind of white blood cell, destroy foreign bacteria, and later, special ‘macrophage’ cells arrive to gobble up (literally, eat) wound debris. They also chemically summon other cells specialised in immune defence. You’ve had bodily infections before – this is a little localized one: you can expect heat, and discomfort, and reddening, and puffiness.

Phase 3: Proliferation

Here’s the part that fascinates dermatologists. It’s new skin construction. They call it the ‘proliferative’ phase.

You get what’s called ‘granulation’ tissue, a shiny red connective matrix, and some new vessels for blood. Then the margins of the wound pull towards each other. Your swelling is gone, but now the area can be sore because it’s crusty and tender. Then you get true skin cells moving up from the bed of the wound or coming in from the edges. This new skin is spoken of as ‘epithelium’.

At the cellular level, skin is complicated, as we’ve shown in other posts, so this proliferation business can take days.

Phase 4: Maturation

And then your skin gets normal. That new tissue organizes itself like mature skin, with properly arranged collagen bundles, and the kind of strength and flexibility you had before, or almost. This can take months, even after your skin looks pretty much healed.

What you can do to help your healing

Skin healing is easy to interfere with. You should keep your wound from drying out, but also from being so moist as to court infection. Just put a little petroleum jelly on it. Vaseline works great. This will also keep it from scabbing up too much, which tends to lengthen healing time. Change the dressings, use an antibiotic cream, and don’t touch it.

Just watch it heal. It’s not exactly fun to get a cut or a scrape. But it can be pretty interesting to see what your body does about it.

Questions about your skin? Ask our dermatologists online for $35.