Ключевые слова: anatomy, animal, arteries, background, biology, blood vessels, capillaries, carbon dioxide, cardiac muscle, closeup view, complex, connective tissue, cross section, cut in half, endothelium, epithelium, functioning, gray background, heart, human body, i organ, intricate details, lung, muscles, organ, oxygen, plasma, platelets, pulmonary circulation, red blood cells, science, scientific, smooth muscle, structure, systemic circulation, tissues, valves, veins, vibrant colors, white blood cells,