Fantasy of Knowledge

You breathe in oxygen from the air. There is oxygen in water too, but the human body cannot take this oxygen from the water. If you tried to take a breath underwater, your lungs would quickly fill up with water and you wouldn’t be able to breathe. Fish and other sea creatures, however, can breathe underwater. They have organs called gills which enable them to take oxygen from the water. But if a fish is taken out of water, its gills dry out and it cannot breath. All body cells need air, or oxygen, to perform their different functions. Without oxygen, these functions would stop completely. Throughout your life you breathe in oxygen continuously and automatically without saying, ‘I will breathe,’ or ‘I won’t breathe.’ Once this oxygen reaches your lungs, it enters small air sacs called alveoli through the alveoli’s very thin walls. These walls are filled with tiny blood vessels, or capillaries. The oxygen enters the capillaries, which carry it to your heart. Your heart then pumps the oxygen-filled blood to all the cells in your body.