Question

If a patient's pulmonary arteries are blocked, less blood flows to the lungs. How would this impact both pulmonary and systemic circulation, and what symptoms might occur?
A. Reduced body oxygen levels would cause fatigue and shortness of breath
B. Increased systemic blood pressure would cause headaches and blurred vision
C. The body would produce more red blood cells to carry more oxygen
D. Blood would be rerouted to other organs, bypassing the blocked lungs

Answer 1

Answer: A.

Explanation:
- Blocking pulmonary arteries (as in a pulmonary embolism) reduces blood flow through the lungs → less gas exchange → systemic hypoxemia. That causes shortness of breath, fatigue, tachypnea, tachycardia, possible cyanosis and mental confusion.
- Hemodynamically, the obstruction raises pressure in the pulmonary circulation and strains the right ventricle; because less blood returns to the left heart, systemic cardiac output and blood pressure may fall (not rise).

Why the other choices are incorrect:
- B: Systemic blood pressure typically falls (or is unchanged), it does not increase to cause headaches/blurred vision.
- C: The body can increase red cell production in response to chronic hypoxia, but this is a slow compensatory response (days–weeks), not an immediate effect of an acute pulmonary arterial blockage.
- D: Blood cannot be rerouted to other organs to become oxygenated; only the lungs oxygenate blood, so perfusion to the lungs must be restored for normal oxygenation.