For many true experimental designs, pretest-posttest designs are the preferred method to compare participant groups and measure the degree of change occurring as a result of treatments or interventions.
Itâs important to note that the flush caused by niacin is not harmful or dangerous. It is actually a sign of improved blood flow and circulation. Also niacin oxygenates the blood. When you get a niacin âflushâ it is an indication that the niacin is causing small blood vessels in your body to expand in size.Many of your small blood vessels, called capillaries, are so small that blood cells can only go through them in single file or if they are flexible enough to fold over.t is actually a sign of improved blood flow and circulation. Also niacin oxygenates the blood. When you get a niacin âflushâ it is an indication that the niacin is causing small blood vessels in your body to expand in size.
Capillaries are the smallest blood vessels in the body. They allow water, oxygen, carbon dioxide, and other nutrient and waste substances to exchange between blood and surrounding tissues.Read on to learn more about capillaries, and what they do in your body.cience Videos. Science Main Index. Capillaries are the smallest blood vessels in the body. They allow water, oxygen, carbon dioxide, and other nutrient and waste substances to exchange between blood and surrounding tissues. Read on to learn more about capillaries, and what they do in your body.