Wähle von der Dropdown-Liste, um den Text zu vervollständigen.
Blood enters the ( atria, aorta, ventricles, pulmonary artery ) of the heart. The ( aorta, pulmonary artery, ventricles, atria ) ( contract, expand ) and force blood into the ( ventricles, atria, vena cava, aorta ). The ( vena cava, aorta, atria, ventricles ) ( contract, expand ) and force blood out of the heart. ( Valves, Veins, Arteries, Capillaries, Tissues ) in the heart ensure that blood flows ( in the correct direction, as quickly as possible, in small increments ). Blood flows from the heart to the organs through ( arteries, veins, capillaries ) and returns through ( veins, capillaries, arteries ).
There are two separate ( circulatory, digestive, respiratory ) systems - one for the ( lungs, heart, kidneys, muscles ), and one for all the other organs in the body.