What does the heart do? It is in charge of pumping blood. The heart has to pump blood both to the body and to the lungs.
Why does the heart need to send blood to the body? To deliver oxygen to all the organs and muscles (and pick up carbon dioxide - which is left over after the cells use the oxygen). Without oxygen, the cells of the body will die.
Why does the heart need to send blood to the lungs? To pick up oxygen (and get rid of carbon dioxide).
Did you know the heart has two sides to do this? The RIGHT SIDE of the heart pumps blood to the lungs. The LEFT SIDE of the heart pumps blood to the body.
Both sides of the heart have two rooms (doctors call them chambers because we like to be fancy). The first chamber is called the ATRIUM. The atrium is like the entryway of a building. It's where the blood enters the heart. The second chamber is called the VENTRICLE. The ventricles is the powerhouse. It is the strong muscle that pumps the blood out of the heart to where it needs to go. Because there is a right and a left side of the heart, there is a right atrium and a left atrium, as well as a right ventricle and a left ventricle.
How does the blood get to the heart? VEINS are the vessels that bring blood back to the heart. Most people think that veins only carry blue blood - or blood without oxygen. But that is actually not true! (read below to find out why). Remember, blood that has already fed the body has to travel back to the heart so it can be pumped to the lungs to pick up more oxygen.
On the right side of the heart, there are two big veins: the inferior vena cava (IVC) and the superior vena cava (SVC). The IVC brings blood from the lower body to the right side of the heart. The SVC brings blood from the upper body (head and arms) to the right side of the heart.
On the left side of the heart, PULMONARY VEINS bring blood back from the lungs. Most often there are four of them. This blood, now filled with oxygen, goes to the left atrium. Since this blood has oxygen, it looks brighter red. The PULMONARY VEINS are the only veins in the body that carry oxygenated or red blood.
The highways or blood vessels that leave the heart are called ARTERIES. Most people think arteries only carry bright red blood that has oxygen. But that is not true either!
On the right side of the heart, there is one big highway that travels to the lungs. This highway is called the PULMONARY ARTERY. It brings blood to the lungs. The PULMONARY ARTERY is the only artery in the body that carries blue blood or blood without oxygen.
On the left side of the heart, there is one big highway that travels to the body. This highway is called the AORTA. It brings blood to the body. This blood carries oxygen and is bright red.