Venice is a seaport city in Italy.
It was built on islands in a lagoon that’s flooded all year. People get around the city using boats, not cars. So what does Venice have to do with blood?
Your circulatory system (blood vessels and heart) is a lot like Venice. The “streets” of that city are a maze of watery canals. The canals are like 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. Your blood vessels branch into smaller tubes. The canals reach every part of the city. Your vessels reach every part of your body.
The likeness doesn’t end there. Twenty-four hours a day, blood leaves your heart. It circulates through your body and then returns to your heart. In Venice, boats leave the station at the “heart” of the city 24 hours a day. They circulate around the canals and then return to the station. Delivery boats act like red blood cells: They ferry food and other useful things all around the city. Garbage boats are like white blood cells. They pick up trash and take it to the dump.