[Campbell Biology P.975] Based on the information in "CONCEPT CHECK 42.1" Question 3, if a n... | Practice Question

Based on the information in "CONCEPT CHECK 42.1" Question 3, if a normally developing human fetus has a hole between the left and right atria that doesn't close before birth, how would this affect the oxygen O₂ content of the blood entering the systemic circuit?

  • A: It would significantly decrease the O₂ content.
  • B: It would significantly increase the O₂ content.
  • C: It would not affect the O₂ content, only the blood pressure.
  • D: The O₂ content would fluctuate unpredictably.

Explanation

A hole between the left and right atria, known as an atrial septal defect, allows oxygenated blood from the higher-pressure left atrium to shunt into the lower-pressure right atrium. This mixing of oxygenated and deoxygenated blood means that the blood eventually pumped into the systemic circuit will have a lower overall O₂ content than normal, compromising oxygen delivery to body tissues.