What is the influence of an increased lung volume on the right ventricle?

A. increased preload
B. increased afterload
C. increased myocardial contractility
D. increased cardiac output

?ANS: B
A. Incorrect response: See explanation B.
B. Correct response: Right and left ventricular ejection are affected by changes in the pleural pressure or by changes in the lung volume during ventilation. For the right ventricle, increased lung volume increases afterload. Right ventricular afterload increases because the pulmonary vascular resistance increases. The increased right ventricular afterload increases also because during lung inflation the right ventricle must pump blood through alveolar vessels (pulmonary capillaries), which are compressed by alveolar pressure.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.