Anatomy and Physiology II Practice Test 2025 - Free Anatomy Practice Questions and Study Guide

Polycythemia refers to an increased concentration of red blood cells in the bloodstream. This condition can significantly elevate the viscosity, or thickness, of the blood. When blood becomes thicker, it can lead to a range of cardiovascular issues because the heart must work harder to pump this viscous fluid. This increased workload can contribute to the development of blood clots, which are a major risk factor for stroke and myocardial infarction (heart attack).

The higher viscosity means that blood flows less freely through the blood vessels, making it easier for clots to form, especially in smaller capillaries or narrowed arteries. Consequently, individuals with polycythemia are at an increased risk for these serious cardiovascular events due to impaired blood flow and potential clot formation.

Therefore, the statement that polycythemia can increase blood viscosity and raise the risk for stroke or myocardial infarction is accurate.