If your child has ever wondered what happens when he gets a cut that bleeds or how to heal a cut, this TED Ed animated video and lesson provides a clear explanation.

It’s a four-step process of healing that’s quite the little miracle:

  1. When something penetrates the outer layer of skin (or epidermis) to the layer below (the dermis), the first reaction is called hemostasis. In this stage, the body marshals its defenses against two threats: the first is that the outer layer of the skin has been breached, and the second is that blood is escaping from the cut.
  2. In stage two, vasoconstriction, the blood vessels tighten up to minimize bleeding and blood cells bunch up at the site and form a clot along with a tough protein in the blood called fibrin, which rushes over and acts like a natural Band-Aid, stopping more blood from getting out and preventing bacteria from invading.
  3. The third stage is inflammation. This is when the body’s defenses really charge in to protect us. White blood cells arrive to destroy any pathogens (which simply mean any disease-producing agent, like bacteria or a virus). As you’ll see in the animation, this stage has several parts to it that promote healing.
  4. The final stage is called remodeling. Depending on the severity of the cut, this stage can take many months in the effort to heal the skin and blood vessels. In a bad cut, a permanent scar will form, which shows that our self-healing ability – while remarkable – is far from perfect!

In the Dig Deeper section of the lesson are a number of interesting links to learn more. The biggest topic is research into other animals that have even better abilities to heal themselves. This is part of a whole branch of medical science called “regenerative medicine.” Watch this two-minute video, for example, to find out about a little mouse from Africa that has remarkable regenerative powers that may hold clues to improving our own. Go further on the topic in this site from the world-famous Mayo Clinic.

Did you like this TED Ed lesson? Take a look at others we’ve selected for your learning pleasure!

Related Topics

Interested in learning more about k12's online schools and courses?