Concept:The mammalian heart pumps blood through separate pulmonary and systemic circuits. The aorta is the main artery of the systemic circuit and arises from the left ventricle.
Explanation:Option A is correct: oxygenated blood from the lungs enters the left auricle through the pulmonary vein.
Option B is correct: the ventricles pump blood out of the heart, so their muscular walls are thicker than those of the auricles.
Option C is not correct: the aorta carries oxygenated blood from the left ventricle to the body, not from the right ventricle to the left auricle.
Blood from the right ventricle goes to the lungs through the pulmonary artery, and blood returns to the left auricle through the pulmonary vein.
Option D is correct: the tricuspid valve prevents backflow of blood into the right auricle.
Answer:C. Blood passes from the right ventricle to the left auricle through the aorta.