The heart is a strong muscular pump that keeps blood moving through the body every moment of life. It sends oxygen-poor blood to the lungs to pick up oxygen, then sends oxygen-rich blood to the body’s cells. This circulation matters because cells need oxygen and nutrients to release energy and stay alive.
A clear heart diagram helps show how chambers, valves, and blood vessels work together in an organized path.
The heart has four chambers: the right atrium, right ventricle, left atrium, and left ventricle. Valves act like one-way doors, opening to let blood move forward and closing to stop it from flowing backward. A heartbeat is one full cycle of filling and pumping, controlled by electrical signals that coordinate the heart muscle.
Healthy habits such as regular exercise, balanced nutrition, enough sleep, and avoiding tobacco help support normal heart function.
Key Facts
- Blood flow path: body to right atrium to right ventricle to lungs to left atrium to left ventricle to body.
- The right side of the heart pumps oxygen-poor blood to the lungs through the pulmonary arteries.
- The left side of the heart pumps oxygen-rich blood to the body through the aorta.
- Valves keep blood moving one direction: atrioventricular valves separate atria from ventricles, and semilunar valves lead out of the ventricles.
- Cardiac output = heart rate x stroke volume.
- Pulse rate in beats per minute can be estimated by counting beats for 15 seconds and multiplying by 4.
Vocabulary
- Atrium
- An atrium is one of the two upper heart chambers that receive blood returning to the heart.
- Ventricle
- A ventricle is one of the two lower heart chambers that pump blood out of the heart.
- Valve
- A valve is a flap-like structure that keeps blood flowing in one direction through the heart.
- Pulmonary circulation
- Pulmonary circulation is the pathway that carries blood between the heart and lungs.
- Systemic circulation
- Systemic circulation is the pathway that carries oxygen-rich blood from the heart to the body and returns oxygen-poor blood to the heart.
Common Mistakes to Avoid
- Mixing up the right and left sides of the heart: diagrams often show the heart as if facing you, so the heart’s right side appears on the viewer’s left.
- Saying arteries always carry oxygen-rich blood: pulmonary arteries carry oxygen-poor blood from the right ventricle to the lungs.
- Thinking valves push blood forward: valves do not pump blood, they open and close because of pressure differences to prevent backflow.
- Skipping the lungs in the blood flow path: blood must travel to the lungs to release carbon dioxide and pick up oxygen before returning to the left side of the heart.
Practice Questions
- 1 A student counts 18 pulse beats in 15 seconds. What is the student’s heart rate in beats per minute?
- 2 A person has a heart rate of 72 beats per minute and a stroke volume of 70 mL per beat. Calculate the cardiac output in mL per minute.
- 3 Explain why the left ventricle has a thicker muscular wall than the right ventricle.