Imagine if a 3year old has only one single blood vessel: The single blood vessel grows by approximately 88 kilometers per day since conception.

Here is the quick calculation using that timeline:

•Total Days: ~1,365 days (270 days in the womb + 1,095 days of life up to age 3).

•Total Length: ~120,000 kilometers.

That breaks down to an astonishing 3.7 kilometers of growth every single hour.

Typical adult walking speed: ~5 km/h . Next time you are walking then imagine the tiny thin blood vessel growing behind you almost at the same speed you are walking. If you slow down and stop it will catch up to you.