Heart Structure & Double Circulation
Describe the structure of the heart (four chambers, valves, coronary arteries) and explain how it pumps deoxygenated blood to the lungs and oxygenated blood to the body in a double circulatory system
What a learner can do afterwards
- Labels a diagram of the heart showing atria, ventricles, valves, aorta, vena cava, and pulmonary vessels
- Traces the route of blood through the double circulatory system
- Explains the role of valves in preventing backflow
- Compares arteries, veins, and capillaries
The lesson
Your heart is really two pumps joined side by side, a right pump and a left pump. Each side has two chambers: an atrium on top that receives blood, and a ventricle below that pumps blood out. A thick wall called the septum keeps the two sides separate, so blood on the right never mixes with blood on the left.
Valves sit between each atrium and ventricle, and where blood leaves the ventricles. They work like one-way doors: blood pushes through, then the valve snaps shut so it cannot slosh backward when the heart squeezes.
Even the heart muscle needs its own blood supply. Coronary arteries branch off the aorta and wrap around the heart, feeding the muscle that never gets to rest. Arteries like these have thick, muscular walls built for high pressure. Veins carry blood back at low pressure and have their own valves to stop it sinking backward. Capillaries are the thinnest vessels of all, so thin that oxygen and nutrients can pass straight through into cells.
The heart is two pumps in one: the right side sends blood to the lungs, the left side sends blood to the body, and valves make sure it only ever flows one way.
Watch it
Where it sits
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.