After reading this passage from my physiology textbook (Vanders Physiology p. 384), I'm confused about how exactly the right and left ventricle can create markedly different pressures as they pump blood even if they have the same stroke volume, i.e. they push out the same amount of blood.
Typical pulmonary arterial systolic and diastolic pressures are 25 and 10 mmHg, respectively, compared to systemic arterial pressures of 120 and 80 mmHg. Therefore, the pulmonary circulation is a low-pressure system, for reasons to be described later. This difference is clearly reflected in the ventricular anatomy— the right ventricular wall is much thinner than the left. Despite the difference in pressure during contraction, however, the stroke volumes of the two ventricles are the same.
How can two ventricles push the same amount of blood but at different pressures? I always assumed that pressure was created by a change in volume of the ventricles, and so I expected that if both ventricles have the same "change in volume" as they contract, they should also push out blood at the same pressures. Why is this not the case?