Page 5, USMLE, Dr. D. Penney



USMLE-Type Examination Questions - Oxygen Exchange & Exercise:


266.  Which of the following is most likely to occur in a healthy subject in response to strenuous running?
	(A)	a decrease in the ejection fraction of the ventricles
	(B)	a decrease in the maximum dP/dt of the left ventricle
	(C)	an increase in circulation time
	(D)	a decrease in arteriovenous O2 difference
	(E)	an increase in concentration of arterial lactate


270.  During strenuous running, the cardiac output of a subject increased four-fold, the systemic AVo2 difference changed from 4 to 12 mL/dL, and the mean pulmonary arterial pressure changed from 15 mmHg to 18 mmHg.  Which of the following conclusions can be drawn?
	(A)	the increased pressure was caused by an increased pulmonary resistance to flow
	(B)	the pulmonary artery blood had a lowered oxygen content during exercise
	(C)	oxygen extraction from the blood increased 6-fold
	(D)	oxygen extraction from the blood increased 9-fold
	(D)	changes in the pulmonary artery blood Po2 are, for the most part, responsible for the changes in the pulmonary peripheral resistance


274.  During running, the cardiac output doubles.  What changes would you expect in the pulmonary system?
		Pulmonary		Pulmonary
		Vascular		Arterial
		Resistance		Pressure
	(A)	a small decrease	a large increase
	(B)	a large decrease	a small increase
	(C)	a large decrease	a small decrease
	(D)	a small increase	a large increase
	(E)	a large increase	a large increase



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