Explore your heart
Four chambers, four valves, and a wiring system that fires roughly a hundred thousand times a day. Select any marker on the diagram to read what that part does and which conditions involve it.
Four rooms, two pumps. The right side sends blood to the lungs; the left side sends it to the body.
Anterior view. The patient’s right side appears on the left, as it would if they were facing you.
One beat, start to finish
Select a marker on the diagram to read about that part. Or follow a single circuit of blood through the heart — it happens about once a second, for your whole life.
- 01
- 02
- 03
- 04
- 05
- 06
A few conventions that make anatomical drawings easier to follow.
Left and right are the patient’s
The diagram shows an anterior view — the heart as it would appear if the person were facing you. Their right side is therefore on your left. This catches almost everyone out at first.
Not about oxygen here
Textbooks usually colour oxygen-rich blood red and oxygen-poor blood blue. This plate is drawn in one palette instead, and the brighter lines on the surface are the coronary arteries.
Electricity, not blood
The broken line traces the conduction system — the route the electrical impulse takes from the sinoatrial node down into the ventricles. It carries signal, not flow.
The same content as the diagram, listed for reading straight through.
Chambers
Four rooms, two pumps. The right side sends blood to the lungs; the left side sends it to the body.
- Right atrium RA
- Blood that has already delivered its oxygen to the body arrives here through two large veins. The right atrium collects it and passes it down into the right ventricle. It also houses the sinoatrial node, the heart's natural pacemaker.
- Right ventricle RV
- The right ventricle pushes blood into the lungs to collect oxygen. It is a thin-walled chamber because that journey is short and low-pressure. When lung pressures rise over time, this chamber has to work against resistance it was never built for.
- Left atrium LA
- Freshly oxygenated blood returns from the lungs into the left atrium, which passes it down to the left ventricle. This chamber enlarges when the mitral valve is diseased or blood pressure has been high for years, and an enlarged left atrium is where atrial fibrillation tends to begin.
- Left ventricle LV
- This is the chamber that does most of the work, driving blood through the entire body. Its wall is several times thicker than the right ventricle's for that reason. When a cardiologist talks about ejection fraction or a weak heart, this is almost always the chamber in question.
Valves
Four one-way doors. They open to let blood through and close to stop it coming back.
- Tricuspid valve TV
- A three-flapped valve that lets blood down into the right ventricle and shuts to stop it washing back into the atrium when the ventricle squeezes. It commonly leaks a little in healthy people, which is a normal finding on an echo rather than a problem.
- Pulmonary valve PV
- Sits at the exit of the right ventricle, opening to release blood towards the lungs and closing to stop it falling back in. Disease here is less common in adults and is usually congenital rather than acquired.
- Mitral valve MV
- The only valve with two flaps rather than three. It is the valve most often damaged by rheumatic heart disease, which remains an important cause in India — narrowing here raises pressure back into the lungs and causes breathlessness.
- Aortic valve AV
- The aortic valve regulates blood flow from the left ventricle into the aorta. It carries the highest pressure of any valve, and with age it can calcify and stiffen. Once a narrowed aortic valve causes chest pain, blackouts or breathlessness on exertion, it needs prompt assessment.
Vessels
The pipes in and out — including the small arteries that feed the heart muscle itself.
- Aorta AO
- The largest artery in the body, arching up out of the left ventricle and running down through the chest and abdomen. Every artery in the body branches from it, including the coronary arteries that feed the heart itself.
- Coronary arteries CA
- The heart is a muscle and needs its own supply, delivered by arteries that branch off the aorta and run across the outside of the heart. These are the vessels that narrow in coronary artery disease and close in a heart attack, and the vessels an angioplasty opens.
- Pulmonary arteries PA
- The only arteries in the body that carry oxygen-poor blood, taking it from the right ventricle to the lungs to be reloaded. Raised pressure in these vessels is called pulmonary hypertension and strains the right side of the heart.
- Pulmonary veins PVn
- Four veins bringing freshly oxygenated blood back from the lungs into the left atrium — the only veins in the body carrying oxygen-rich blood. The point where they join the atrium is where the abnormal electrical activity of atrial fibrillation usually starts.
Electrical system
The heart makes its own signal. This is the wiring that sets the pace and the order.
- Sinoatrial node SA
- A small patch of specialised tissue in the wall of the right atrium that generates the electrical impulse starting every heartbeat, around 60 to 100 times a minute at rest. It speeds up and slows down in response to activity and hormones without any conscious instruction.
- Atrioventricular node AV-N
- The impulse pauses here for a fraction of a second on its way from the atria to the ventricles. That delay lets the upper chambers finish emptying before the lower ones contract. It also acts as a gatekeeper, shielding the ventricles from very fast atrial rhythms.
- His–Purkinje system HPS
- A branching network of fast-conducting fibres that carries the impulse from the AV node throughout both ventricles, so the whole chamber contracts almost at once rather than in a slow ripple. Damage to one branch produces the bundle branch block often reported on an ECG.
Have a question about your own heart?
A consultation is where a general diagram becomes your specific answer.
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Gwalior 474001
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