right side of the heart pumps deoxygenated blood to the lungs
left side of the heart pumps oxygenated blood to the whole body
Veins carry blood to the heart (vena cava and pulmonary vein) and arteries carry blood away from the heart (pulmonary artery and aorta)
left ventricle: has thicker, more muscular walls than the right ventricle - this allows it to contract more powerfully and pump blood all the way around the body.
The right ventricle is less muscular and so its contractions are only powerful enough to pump blood to the lungs as they are nearby
ventricles have thicker walls than the atria therefore they can push blood out of the heart, whereas the atria just need to push blood a short distance into the ventricles
the atrioventricular valves link the atria to the ventricles and stop blood flowing back into the atria when the ventricles contract
the semi-lunar vales link the ventricles to the pulmonary artery and aorta, and stop blood flowing back into the heart after the ventricles contract
the cords attach the atrioventricular valves to the ventricles to stop hem being forced up into the atria when the ventricles contract
Heart valves - only open one way - whether they're open or closed depends on the relative pressure of the heart chambers. If there is higher pressure behind a valve it is forced open but if pressure is higher in front of the valve it is forced shut. This means that the flow of blood is unidirectional - it only flows in one direction
