During heavy exercise the cardiac output (CO) increases upto five fold while pulmonary aerial pressure rises very little. This physiological ability of the pulmonary circulation is best explained by:
A i.e. Increase in the number of open capillaries
Increase in the number of open capillaries
Sympathetically mediated greater distensibility of pulmonary vessels
Large amount of smooth muscle in pulmonary aerioles
Smaller surface area of pulmonary circulation