Which factor does NOT determine blood pressure?

Lung function does not play a direct role in determining blood pressure. Blood pressure primarily depends on the dynamics of the heart, blood vessels, and the characteristics of the blood itself.

Cardiac output refers to the amount of blood pumped by the heart in a minute, which directly influences blood pressure; higher output generally leads to higher pressure. Blood viscosity is the thickness of the blood, affected by various factors such as hydration and blood cell count, and it influences how easily blood moves through the vessels, thereby affecting pressure. Arterial resistance, which refers to the degree of constriction in the blood vessels, is a significant factor that determines how much pressure is needed to circulate blood.

In contrast, while lung function is essential for oxygenating blood and removing carbon dioxide, it does not directly affect the pressures in the arterial system. Thus, among the options, lung function is the factor that does not influence blood pressure.