the Homo Sapiens (Humans)
Humans have been a dominant species on the planet for thousands of to survive years, utilizing agriculture, animals, and tools to survive and thrive as a group. They have made great bounds in areas of science, language, travel, etc. They have even deduced the idea of evolution with species, connecting groups of animals, including themselves, to common ancestors that adapted and survived.
The system
Humans have a closed cardiovascular system, consisting of blood, arteries, veins, and a heart with chambers (left and right ventricle and atria). Its purpose is to pump blood through the body to supply nutrients to the muscles and cells. Blood cells that have lost their oxygen are transported through the lungs to the right and left pulmonary veins into the left atrium. From there, the blood full of oxygen moves into the left ventricle, then pumped out of the heart through the aorta to the rest of the body. After the oxygen has been distributed, the blood comes back through the inferior and superior vena cava into the right atrium, then the right ventricle. It is then pumped out of the heart through the left and right pulmonary arteries through the lungs where they receive oxygen again.