Human Heart & Double Circulation 3D Simulation

This 3D lab shows the human heart the way a textbook diagram of double circulation does, but beating. Four chambers contract in the right order, the tricuspid, bicuspid and semilunar valves open and shut on cue, and blood cells flow from the venae cavae through the right side of the heart to the lungs, back through the left side and out through the aorta to the body organs. Cells are blue while they carry oxygen-poor blood and turn red in the lung capillaries, then blue again in the body's capillaries, so the two circuits are easy to follow.

The lab has four modes. Explore lets you click any chamber, valve, vessel, the lungs, the body organs or the conduction system to read its structure, function and the points NEET asks about, with a live ECG strip that marks the phase, the valve states and each 'lub' and 'dub'. Processes plays three sequences step by step: double circulation (nine steps, following a single red cell), the cardiac cycle (each phase in slow motion) and how each beat starts (SA node, AV node, bundle of His, Purkinje fibres). Experiment changes heart rate and stroke volume to show cardiac output, and adds a hole in the ventricular septum or a leaky bicuspid valve. Missions ask you to find parts, trace a red cell round the body by clicking each stop, and answer NEET questions.

The numbers follow NCERT's Body Fluids and Circulation: about 72 beats a minute, a cycle of about 0.8 seconds split into 0.1 s atrial systole, 0.3 s ventricular systole and 0.4 s joint diastole, a stroke volume of about 70 mL and a cardiac output of about 5 litres a minute. The defects are an illustrative model that shows the direction of the change, not clinical values.