Reply To: Question 84

#29489
Max Kinne
Moderator

Hi Sharanya,

The correct answer is A (which is the answer provided in Answers and Explanations on page 283). Note, the question is asking for the incorrect answer choice (all of the following EXCEPT).

Normally, the ductus arteriosus, a blood vessel connecting the aorta and the pulmonary artery, closes at birth. In patent ductus arteriosus, this vessel does not close. As a result, oxygenated blood from the aorta (that is normally pumped to tissues) passes back through this vessel into the pulmonary artery. The pulmonary artery normally carries deoxygenated blood to the lungs. In patent ductus arteriosus, the pulmonary artery will also carry oxygenated blood from the aorta. Thus, blood flow to the lungs (pulmonary circulation) will have more oxygen that normal. The blood that reaches the tissues (systemic circulation) will have less oxygen than normal (the opposite of answer choice A) due to this shunting of blood from the aorta to the pulmonary artery.

Does this clarification help?

Max

  • This reply was modified 1 month ago by Max Kinne. Reason: Clarification of pulmonary vs. systemic circulation