Sources and simplifications
  • A four-chamber section with the ventricles' long axes straightened to vertical; the outflow roots (aortic, pulmonary) are drawn in the same plane, though they lie in front of it.
  • Chamber sizes and wall thicknesses are typical adult values (LV wall ~11 mm, RV ~4 mm), rounded.
  • Pressures follow the Merck averages through a smooth textbook Wiggers model, not a measured trace; right-heart pressures are the left's shape, scaled.
  • Blood is coloured by oxygen saturation (dark red at 75%, bright red at 95%), not blue: venous blood is not blue.
  • Conduction timing is schematic: the atria activate from the SA node, the AV node holds the wave, then the ventricles activate from apex to base.
  • Only two leaflets or cusps of each valve lie in the section; the tricuspid and the semilunar valves have three.

Sources:

SA node: the pacemaker; the glow is the electrical waveSection through the four chambers, walls hatched, blood filledValves open and close with the pressure differencesThe human heart in a four-chamber section, as a three.js scene. Blood returns from the body to the right atrium, passes the tricuspid valve into the right ventricle, and is pumped through the pulmonary valve to the lungs. It returns to the left atrium, passes the mitral valve, and the left ventricle pumps it through the aortic valve to the body. Average resting pressures are LV 130/9, aorta 130/70, RV 25/4, PA 25/9, LA mean 8 and RA mean 3 mmHg [1]. Blood is coloured by oxygen saturation, about 75% in the right heart and 95% in the left [2]. Each beat starts at the SA node, crosses the atria, is held at the AV node (a PR interval of 0.12–0.2 s), then runs down the His bundle and bundle branches into the Purkinje fibres [3]. Valves open only when the pressure behind them exceeds the pressure ahead. Both sets are shut during the isovolumetric phases [5]. At higher rates diastole shortens much more than systole: ejection time ≈ 413 − 1.7 × HR ms [4]. The monitor plots the model's Wiggers diagram. The scene uses a fibre texture on the muscle, saturation vertex colours on the blood, flow shaders on the vessels and a glow shader for the wave. The animation runs at half speed.