I’m always amazed by the fact that human body (or any creatures including plants) have an amazing design and system to fight off infections (immune response) and repairs for any damages.
I was particularly interested in why limbs don’t grow back if my finger that had a nasty cut recovered. If my cells know how to recover the damages on my finger why wouldnt they grow back a limb?
In: Biology
Skin can grow back over a wound because it’s just one type of tissue making more of itself to fill a gap. Same goes for e.g. a torn muscle or broken bone: as long as you’re filling in a (small-ish) gap with the same tissue, the body can generally do it.
In general, your body replaces most of your tissues regularly. Skin is constantly being shed and replaced, and most of your cells are renewed every few years, with very few exceptions. So your body is naturally able to make more of what’s already there.
Losing a limb is a different story though. To regrow a limb, you have to grow several new bones from scratch, as well as new muscles, new skin, new ligaments, new everything. And it’s not just filling a gap, it’s growing these tissues in the correct shapes too. This is an ability that your body has during development in the womb, but not after.
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