5G · Reading Charts on the Exam
The exam asks you to analyze information from charts without drawing. Every course chart answers the same four questions: what is on each axis, what the shape means, where the key points sit, and what shifts the curve. Practice each one in Problems › Chart.
Chart | Read off | What shifts it |
|---|---|---|
Membrane potential trace (M2 s37–39) | Rest −70, threshold −55, peak +30, 1 ms, undershoot | Channel timing; refractory periods |
Summation traces (M2 s32) | Single EPSPs below threshold; summed reach it; IPSPs cancel | Timing (temporal) and number of inputs (spatial) |
Conduction velocity (M2 s42) | Myelin wins above about 1 µm; λ 3 mm vs 1 mm; velocity up to 5× at 40°C | Myelin, diameter, temperature |
EC coupling timeline (M3 s22) | AP → free Ca2+ → Ca-TnC → force, in that order | SERCA speed sets the decay |
Length-tension (M3 s35) | Peak 2.0–2.3 µm; zero at 1.3 and 3.7 µm; total = active + passive | Filament overlap |
Stimulation frequency (M3 s36) | 5, 10, 25, 50 Hz: twitch, summation, unfused, fused | Residual Ca2+ |
Load-shortening (M3 s44) | Latent and isometric delay, distance, slope = velocity | Load |
Force-velocity and power (M3 s45–46) | Vmax at zero load, Fmax at zero velocity, power peak at 1/3 | Fiber type; phosphorylation (smooth); preload (cardiac) |
Fatigue and twitch speed (M3 s31) | Type I flat for 30 min; Type II gone by 5 | Fiber type |
Ca2+ sensitivity (M4 s22) | Same Ca2+, different phosphorylation | MLCP: low shifts toward sensitization, high toward desensitization |
Cardiac AP (M4 s32) | −90 to +20 mV, phases 0–4, about 200 ms | Ion channels by phase |
Frank-Starling (M4 s37) | Stretched curve higher and left | Preload |
Twitch comparison (M4 s45) | Skeletal < cardiac < smooth | Tissue |