Explain how blood is pumped through the body.

Blood from the veins is collected in the right and left atria of the heart. The atria can contract because of the impulses from the sinoatrial node (SA) (the heart’s natural pacemaker). When this happens, the atria contract, the atrioventricular valves open, and the blood flows in the ventricles (this is the atrial systole). After the ventricles fill up with blood, the ventricles contract and the semilunar valves open, in order for the blood to be pumped towards the body or the lungs. The ventricular contraction period is called the ventricular systole. While this happens, the atrioventricular valves close to ensure that blood does not flow back towards in the atria, as blood pumped from the ventricles has very high pressure. The blood from the right atria and ventricle is deoxygenated blood collected from the body . This will be collected in the right atria from the 2 vena cavas. It will then flow into the right ventricle and from there it will be pumped into the pulmonary arteries and delivered to the lungs for oxygenation. The oxygenated blood then enters via the pulmonary veins into the left atria, then the left ventricle; from there it will be pumped into the aorta and delivered to the rest of the body.