Venice, a seaport city in Italy, was built on islands in a lagoon, which stays flooded all year.
Boats—not cars—transport people from one part of the city to the other. So, you might ask, what does this have to do with blood?
Your circulatory system (blood vessels and heart) is a lot like Venice. The “streets” of Venice are a circular maze of watery canals. The canals are like the watery plasma that flows through your blood vessels. There’s a big, central Grand Canal, just as you have major arteries and veins. It branches into smaller and smaller canals, just as your blood vessels branch into smaller tubes. The canals reach every part of the city; your vessels reach every part of your body.
The similarity doesn’t stop there. Twenty-four hours a day, blood leaves your heart to circulate through your body and then return to your heart. Likewise, boats leave the station at Venice’s “heart” 24 hours a day. They circulate around the canals and then return to the station. Delivery boats act like red blood cells, ferrying food and other needed items all around the city. Garbage boats are more like white blood cells, picking up trash and taking it to the dump.
