An organ consisting of the right
atrium, right
ventricle, left atrium, and left ventricle. Non-oxygenated
blood enters the heart through the
precava and
postcava (large veins from the rest of the body) and oxygenated blood leaves through the
aorta.
Pulmonary arteries and
veins carry the blood over the
lungs in order for it to become oxygenated and
recycled through the body.
If you have ever held a heart in your hand (the closest I have ever come is a cat's heart during Biology class), you will know that it is a beautiful, perfect, powerful thing.