GATE 2023 BM – Question 60
Inspired air contains 20% oxygen and expired air 16%. A person breathes 12 times per minute with tidal volume 500 mL and cardiac output 5 L/min. Find the percentage oxygen extracted from each litre of blood in this model, to one decimal place.
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Show answer and explanation
Correct answer: 4.8 to 4.8
Explanation
Minute ventilation=12×.5=6 L/min. The oxygen difference is .20−.16=.04, so uptake is 6×.04=.24 L O₂/min. Dividing by the five litres of blood pumped per minute gives .048 L O₂/L blood. Expressing this volume fraction as a percentage gives 4.8%.