How does oxygen get from outside of the body into the body's organs work?

Answer 1

• Humans use their respiratory system to inhale air.
• The air enters the alveoli, millions of tiny sacks in the lungs, that are surrounded in capillaries (tiny vessels that contain blood).
• The oxygen from the air then diffuses into the capillaries. The blood inside them has now become oxygenated.
• The tissues and organs of the body receive this oxygen with the circulatory system.
• The oxygenated blood travels via the pulmonary veins to the heart, where it is pumped through the aorta (a large artery at the top of the heart) towards the body's tissues via arteries and capillaries.
• Oxygen, water and nutrients reach organs when they diffuse out of the capillaries and become tissue fluid. This process is called pressure filtration.
• The oxygen in the tissue fluid diffuses into cells. This oxygen is then used by the mitochondria, an organelle which produces ATP (the type of energy that the body gets from oxygen).
• Oxygen is necessary to survive because the body needs it to produce ATP, an energy that is needed for the body's cells, tissues and organs to function. The energy gained from food isn't sufficient enough to keep humans alive, and this is why we need to respire.