Muscle Contraction, step by step
The cross-bridge cycle.
- Impulse arrivesCalcium released from the sarcoplasmic reticulum.
- Calcium binds troponinTropomyosin moves, exposing binding sites on actin.
- Cross-bridge formsMyosin head attaches to actin.
- Power strokeThe head pivots, pulling actin inward. ADP released.
- ATP detaches the headNo ATP means no detachment — which is rigor mortis.
What shortens
- Sarcomere gets shorter
- I band and H zone narrow
- A band stays the same length
The A band's constant length is the key evidence for sliding rather than shortening filaments.
Questions about the Muscle Contraction poster
- What’s on the Muscle Contraction poster?
- 5 numbered steps, with a full worked run-through. The cross-bridge cycle. Impulse arrives — Calcium released from the sarcoplasmic reticulum.; Calcium binds troponin — Tropomyosin moves, exposing binding sites on actin.; Cross-bridge forms — Myosin head attaches to actin.; Power stroke — The head pivots, pulling actin inward. ADP released.; ATP detaches the head — No ATP means no detachment — which is rigor mortis.. The A band's constant length is the key evidence for sliding rather than shortening filaments.
- Who is the Muscle Contraction poster for?
- Muscle Contraction belongs to the Biology section rather than to a school year, because life science is not something one grade owns. Anyone learning physiology can pin it up — a beginner, a student mid-course, or someone revising years later.
- When should you use the Muscle Contraction poster?
- The filaments do not shorten. They slide past each other. A wall chart earns its place by being glanceable from where the work is happening, so Muscle Contraction belongs on the wall where that life science work actually happens, within glancing distance, rather than filed away.
- What other posters go with Muscle Contraction?
- Blood Glucose Control, The Cardiac Cycle and The Circulatory System sit alongside Muscle Contraction in the Biology section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Blood Glucose ControlThe Cardiac CycleThe Circulatory System
- Is the Muscle Contraction poster free to download and print?
- Yes. Muscle Contraction downloads as a free PDF with no account, no email and no watermark, like everything else in the Biology section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the Muscle Contraction poster print at?
- Muscle Contraction is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Muscle Contraction loses nothing.Printing guide
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