How does increased blood viscosity affect vascular resistance?

Increased blood viscosity directly impacts vascular resistance by making it harder for blood to flow through the vessels. When blood viscosity rises, the thickness of the blood increases, which in turn requires more force for the heart to pump blood through the circulatory system. This combination of factors means that the blood encounters greater resistance as it moves through the blood vessels.

Higher viscosity affects the flow dynamics, leading to a reduced flow rate if the pressure is constant. Consequently, as blood becomes thicker, the heart and vascular system must work harder to maintain adequate circulation, which can lead to cardiovascular issues over time. This physiological relationship is crucial for understanding how various conditions, such as dehydration or certain diseases, can impact overall vascular health.

The other options do not align with the established physiological principles governing blood flow and vascular resistance.