Ventricular Volume Decrease Indicates Contraction

Steps:

• Examine the graph: volume starts high at end-diastole, then changes over the cardiac cycle.
• Identify systole: period when ventricular volume falls as blood is pumped out.
• Locate contraction phase: corresponds to the downslope where volume decreases rapidly.
• Match to choices: B aligns with the ejection (volume reduction) segment.

Why B is correct:

• Contraction (systole) ejects blood, reducing ventricular volume per the Frank-Starling law relating muscle tension to output.

Why the others are wrong:

• A: Shows diastolic filling, where volume increases as atria pump blood in.
• C: Represents isovolumetric relaxation, where volume stays constant post-ejection.
• D: Indicates end-systolic pause before refilling begins.

Final answer: B