Heart Structure and Blood Flow
Think of your heart as having two separate sides that work together - the right side deals with getting blood to your lungs, whilst the left side pumps it around your entire body. Each side has two chambers: an atrium (the top bit) and a ventricle (the bottom bit that does the heavy lifting).
The right atrium receives deoxygenated blood from your body through the vena cava - think of this as blood that's been used up and needs refreshing. When it contracts, it pushes this tired blood down into the right ventricle, which then pumps it to your lungs via the pulmonary artery.
Meanwhile, the left atrium receives lovely fresh oxygenated blood from your lungs through the pulmonary vein. The left ventricle - the strongest chamber of all - then contracts powerfully to push this oxygen-rich blood through the aorta (your body's biggest artery) to supply your entire body.
Quick Tip: Remember that arteries carry blood away from the heart, whilst veins bring blood back to the heart - regardless of whether it's oxygenated or not!
Valves are like one-way doors that prevent blood from flowing backwards. The tricuspid and bicuspid valves stop blood going back into the atria, whilst the pulmonary and aortic valves prevent backflow from the arteries. Your heart also has special pacemaker cells in the left atrium that act like a natural electrical system, keeping your heartbeat steady and regular.