Home▸Biophysics▸Muscle Contraction: The Sliding Filament Theory

💪 Muscle Contraction: The Sliding Filament Theory

Interactive 3D sarcomere model where users trigger calcium release and myosin cross-bridge cycling, adjusting ATP availability to see actin and myosin filaments slide and the sarcomere shorten.

Biophysics2DAdvanced60 FPS

A 3D sarcomere model where calcium release exposes actin binding sites and ATP-fueled myosin cross-bridges ratchet the thin filaments inward, shortening the sarcomere without the filaments themselves changing length.

🔬 What It Demonstrates

Calcium controls how many actin binding sites are exposed; ATP controls how fast myosin heads can cycle through bind–pull–release. Together they set both the strength and speed of the sarcomere's shortening, and without ATP the cross-bridges lock in a rigor state.

🎮 How to Use

Raise Ca²⁺ release to expose more binding sites, adjust ATP to change cycling speed, and press Stimulate to fire a single twitch. Watch the sarcomere length, cross-bridge state and troponin site occupancy update live as the filaments slide.

💡 Did You Know?

Drop ATP to zero after a contraction and the myosin heads freeze mid-cycle, bound to actin and unable to let go — the same cross-bridge lockup responsible for rigor mortis in muscle tissue after death.

⚙ Under the hood

Interactive 3D sarcomere model where users trigger calcium release and myosin cross-bridge cycling, adjusting ATP availability to see actin and myosin filaments slide and the sarcomere shorten.

sliding-filament-theorymuscle-contractionsarcomeremyosinactinphysiology

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install