Which of the Following is Designed to Promote the One-Way

Question

Which of the following is designed to promote the one-way flow of blood?
A) The slow velocity of blood flow in the capillaries
B) The presence of valves in the veins
C) The presence of smooth muscle in the arterioles
D) The presence of a tunica adventitia in all blood vessels

Accepted Answer

Valves in the veins prevent the backflow of blood and promote the one-way flow of blood towards the heart. The slow velocity of blood flow in the capillaries is important for gas and nutrient exchange, but it does not directly promote the one-way flow of blood. Smooth muscle in arterioles plays a role in regulating blood pressure and distribution of blood flow, but it does not specifically promote one-way flow of blood. The tunica adventitia is the outer layer of blood vessels and does not directly promote the one-way flow of blood.