Human Heart

Published: 01 Aug 2026

Interactive Human Heart Lab

Explore heart structure, follow the path of blood, understand the heartbeat cycle, and practise key Class 9 Biology concepts.

Structure Explorer

Select a heart part

Right atrium: receives deoxygenated blood returning from the body through the venae cavae.

Blood colour key

Deoxygenated blood Oxygenated blood

This is a simplified educational diagram. It is designed to show chambers, major vessels, valves, and the direction of blood flow clearly.

Follow the blood

Blood-flow steps

Animation speed1.0×

Deoxygenated Oxygenated

Body

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Vena cava

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Right atrium

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Right ventricle

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Pulmonary artery

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Lungs

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Pulmonary veins

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Left atrium

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Left ventricle

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Aorta

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Body

Current stage1/11

Blood stateDeoxygenated

Main organBody

Cardiac cycle

Choose a phase

The animation is simplified. It focuses on chamber contraction, relaxation, and the opening or closing of valves.

Diastole

Right atrium

Left atrium

Right ventricle

Left ventricle

AV valvesOpen

Semilunar valvesClosed

Self-check

Human Heart Practice

Question 1 of 8

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Four chambersRight atrium, right ventricle, left atrium, and left ventricle.

Right sideReceives deoxygenated blood from the body and pumps it towards the lungs.

Left sideReceives oxygenated blood from the lungs and pumps it to the body.

ValvesHelp keep blood moving in one direction and prevent backflow.

SeptumSeparates the right and left sides of the heart.

AortaThe major artery carrying oxygenated blood from the left ventricle to the body.

Pulmonary arteryCarries deoxygenated blood from the right ventricle to the lungs.

Pulmonary veinsCarry oxygenated blood from the lungs to the left atrium.

SystoleA phase in which a chamber contracts.

DiastoleA phase in which the heart muscle relaxes and the chambers fill.

No API, external image, or paid service is used. All visuals are drawn with HTML, CSS, SVG, and JavaScript.