Video: The Great Migration: Definition & Causes. The economic conditions of World War I led to a massive movement of African Americans from the South to the North, known as the Great Migration. Examine the causes and effects of this phenomenon.
Physicians may want to look closer at WBC levels when obtaining the tests for other reasons, Manson notes. However, infections can cause a high white blood cell count that may make it appear that a patient is at high risk for heart disease when she is not. Therefore, routinely giving everyone the test to screen for heart disease is premature. More research needs to be done..
Blood Flow. Rising carbon dioxide levels and oxygen demands force your heart to contract more frequently, which increases your heart rate during exercise. Blood flow increases as your heart pumps more oxygen and nutrients through your circulatory system's systemic portion. The systemic circulatory system includes blood vessels that deliver oxygen and nutrient-rich blood to tissues throughout your body.