how does my heart pump blood?

Question

askNib · Accepted Answer

Your heart is a fist-sized muscle that beats about 100,000 times a day, squeezing blood through your whole body. It's really two pumps side by side, each split into an upper chamber and a lower chamber. Tired, low-oxygen blood comes in from the body, enters the right side, and gets sent to the lungs to reload on oxygen. Freshly oxygenated blood returns, enters the left side, and gets blasted out through the aorta to feed every cell in your body. Little one-way valves between chambers snap shut after each squeeze — that snap is the 'lub-dub' sound you hear with a stethoscope. Zoom out and it's one big loop: heart to lungs for oxygen, back to heart, out to the body, and home again — forever, without you thinking about it. So every beat is a tiny two-stage pump, looping oxygen out to your body and back again, nonstop, your whole life.