Body Fluids And Circulation

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Given that a heart ejects a stroke volume of 70 mL with each beat while beating 72 times every minute, what is the approximate cardiac output?

RankGuru · Accepted Answer

Cardiac output is defined as the volume of blood pumped by each ventricle in one minute, and it equals stroke volume multiplied by heart rate. Using the relationship given in NCERT Class 11, Chapter 18 (Body Fluids and Circulation), stroke volume here is 70 mL and heart rate is 72 beats per minute, so cardiac output equals 70 x 72 = 5040 mL per minute, approximately 5 litres per minute. This matches the textbook statement that a healthy individual has a cardiac output of about 5 litres in a normal resting state. The option 142 mL incorrectly adds 70 and 72 instead of multiplying. The value 720 mL multiplies the rate by only ten and ignores the true stroke volume, giving a physiologically far too small output. The figure 1008 mL is obtained by an unrelated incorrect product and does not represent any standard cardiac parameter. Hence 5040 mL per minute is correct. A magnitude sanity check confirms the result: since the body's total blood volume is roughly 5 litres, the heart effectively circulates the entire blood volume once each minute at rest, which is exactly what 5040 mL per minute implies.

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