Your heart is your body's pump and it is about as big as your fist. It's made out of a strong muscle that squeezes together to make your heart beat.
When your heart beats, it pumps blood out of your heart through tubes called arteries. After the blood goes to your toes
and your nose (and every other part of your body), it comes back to your heart through tubes called veins.
The heart has four parts called chambers. There are two chambers upstairs and two chambers downstairs. The upstairs chambers are called the atria. The downstairs chambers are called the ventricles.
Your heart also has valves, which act like little doors. These "doors" open and close while your heart pumps. Their job is to keep the blood moving in the right direction.
The different parts of your heart work together as a team. When your heart beats, the upstairs (atria) fills up with blood from your lungs (see picture). Next, the blood is pumped into the downstairs (ventricles) of the heart. Finally, the blood is pumped out of the heart to the rest of your body through the arteries. Your heart has a lot of work to do, which is why we want to take good care of it.