Blood is Moved Efficiently Through the Veins and Back to the Heart

Question

Blood is moved efficiently through the veins and back to the heart by ____.  
A) one-way valves to prevent backflow
B) smooth muscle contraction
C) skeletal muscle contraction
D) a and b only
E) a, b, and c

Accepted Answer

Blood is moved efficiently through the veins and back to the heart by one-way valves to prevent backflow, smooth muscle contraction, and skeletal muscle contraction. The one-way valves ensure blood flows in one direction towards the heart, smooth muscle contraction helps propel blood through the veins, and skeletal muscle contraction, especially during movement, aids in pushing blood back to the heart.