During which phase of the cardiac cycle are all four cardiac valves closed while ventricular volume remains constant and ventricular pressure rises sharply?
- A Isovolumetric contraction ✓
- B Rapid ejection
- C Rapid ventricular filling
- D Atrial systole
Correct answer: A. Isovolumetric contraction
Explanation
During isovolumetric (isovolumic) contraction the AV valves have already closed and the semilunar valves have not yet opened, so ventricular volume is fixed while pressure rises rapidly. Ejection begins only once ventricular pressure exceeds aortic/pulmonary pressure.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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