شرح Human transport system - احياء لغات 2 ثانوى الترم الثانى

The human transport system is a system of tubes with a pump and valves to ensure one way blood flow. We need a transport system to deliver oxygen, nutrients and other substances to all our body cells, and take away waste products from them. The oxygenated blood (high in oxygen, red in color) comes to the heart from the lungs in the pulmonary vein; the heart pumps it to the aorta (an artery) to the rest of the body. The deoxygenated blood returns to the heart from the body in the vena cava (a vein), the heart pumps is to the lungs to get rid of the carbon dioxide. Oxygenated Blood: Red color, high oxygen low Carbon dioxide. Deoxygenated Blood: Blue color, low oxygen high Carbon dioxide. Did you notice that during one circulation, the blood went through the heart twice, this is why we call it double circulation. When the blood is flowing away from the heart, it has a very high pressure, when it is flowing towards the heart it has a lower pressure.