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.
Arterioles are the smallest arteries in the body. They deliver blood to capillaries. Arterioles are also capable of constricting or dilating and, by doing this, they control how much blood enters the capillaries. Capillaries are tiny vessels that connect arterioles to venules.They have very thin walls which allow nutrients from the blood to pass into the body tissues. Waste products from body tissues can also pass into the capillaries. For this reason, capillaries are known as exchange vessels.Groups of capillaries within a tissue reunite to form small veins called venules. Venules collect blood from capillaries and drain into veins. Veins are the blood vessels that carry blood back to the heart.enules take blood from the capillaries to the veins. Veins take blood back to the heart. This constant circulation of blood keeps us alive. Your blood vessels also play a part in the regulation of your blood pressure. Certain chemicals in the body can cause our blood vessels either to contract or dilate.