Sarcomere & Sliding Filament Tournament
Ten rounds, one of every TEAS-style format. Label real muscle structures on a live Reactome pathway diagram, order the cross-bridge cycle, match sarcomere regions to their definitions, count calcium ions per troponin, identify what shortens during contraction, and pick the odd filament out.
Take a moment with the full diagram
Drag to pan, scroll or pinch to zoom. Trace the substrates, products, and any regulatory inputs you see. When you hit Begin tournament we'll zoom in on each question, so this is your chance to study the full pathway end-to-end.
10 timed rounds - perfect run = 2000 points. You'll pick a leaderboard handle at the end.
What this tournament tests
The ten rounds cover every TEAS-style format used for the Muscular System section and stretch you across the full sliding-filament story: structure recall, sequence of events, regulation, and quantitative recognition.
Visual Labeling
Identify a structure (calcium ion) highlighted directly on the live Reactome Striated Muscle Contraction diagram.
Fill in the Blank
Recall the protein that physically blocks myosin-binding sites on actin in the resting state.
Disruptor
Reason about consequences: what happens to contraction if calcium release is blocked?
Hot Spot
Click the structure that hydrolyzes ATP to power the cross-bridge power stroke.
Data Interpretation
Read a length-tension curve and identify the sarcomere length where force is maximal.
Sequence Ordering
Place the cross-bridge cycle steps in order from Ca2+ binding to ATP recocking.
Match the Pairs
Match each sarcomere region (Z-disc, A-band, I-band, H-zone, M-line) to its definition.
Numeric Input
Recall how many Ca2+ ions bind one troponin C complex to expose actin-binding sites.
Select All That Apply
Identify which sarcomere structures actually shorten during contraction (and which stay constant).
Odd One Out
Distinguish thin-filament proteins (actin, tropomyosin, troponin) from thick-filament myosin.
Built for active recall
Every round forces retrieval - the strongest signal that knowledge will hold up on exam day.
Sliding filament theory in 60 seconds
A sarcomere is the smallest contractile unit of skeletal muscle, bounded by two Z-lines. Inside it, thin filaments (actin) interdigitate with thick filaments (myosin).
At rest, tropomyosin covers myosin-binding sites on actin, held in place by troponin. When a motor neuron fires, the sarcoplasmic reticulum releases calcium (Ca²⁺). Ca²⁺ binds troponin C, which shifts tropomyosin and exposes the binding sites.
Myosin heads (already cocked using ATP energy) bind actin, perform a power stroke, release ADP + Pᵢ, then bind a fresh ATP to detach. ATP hydrolysis re-cocks the head. Repeated cycling pulls actin past myosin and the sarcomere shortens.
When neural firing stops, Ca²⁺ is pumped back into the sarcoplasmic reticulum (an active, ATP-requiring process), tropomyosin returns to cover the binding sites, and the muscle relaxes. No ATP = no detachment = rigor mortis.
FAQ
What is the sliding filament theory?
It explains muscle contraction as actin filaments sliding past myosin filaments toward the center of the sarcomere, driven by myosin cross-bridges and powered by ATP. The filaments themselves do not shorten; the sarcomere does.
Do I need an account to play?
No. The tournament is fully public. You get a randomized name and your scores save locally in your browser.
Is this aligned to the ATI TEAS 7?
Yes. Skeletal muscle structure (sarcomere, actin, myosin, tropomyosin, troponin) and the contraction mechanism are explicit ATI TEAS 7 A&P objectives. Item difficulty targets the test's typical DoK 1-2 range.
Where does the labeling diagram come from?
It is the Reactome Striated Muscle Contraction pathway (R-HSA-390522), CC BY 4.0. We render the original SVG and overlay quiz hotspots on the actual entity bounding boxes.
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Diagram: Reactome Pathway Striated Muscle Contraction (R-HSA-390522), licensed CC BY 4.0.