The millions of structures in the kidneys that filter toxins out of urine are called:

Nephrons

Nephrons are the basic structural and functional units of the kidneys.  Each of the kidneys contains over a million nephrons. Nephrons function by filtering blood and then removing needed substances from the filtrate before eliminating the remaining fluid that contains water, metabolic waste, and toxins.as urine. This process occurs through three stages which are ultrafiltration, selective reabsorption and osmoregulation.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.