Air contains only about 60% oxygen. When someone is having difficulty breathing, there is ususally a heart or lung condition. As the heart pumps, it allows for and exchange of co2 and o2. When there is a dysfunction, the person cannot pull out all of the o2 from the air and need 100% o2 in order to have levels that are able to sustain life.
Yes, John Smith is a person, and like all people, he needs to breathe oxygen to survive. This is a basic biological need for all humans.
causation
causation
My mother needs to use her oxygen tank to breathe.
You breathe faster after exercising as your body needs to remove all the waste products it has produced - carbon dioxide and water.
oxygen
Oxygen is what you breathe in, and what your body needs to function correctly (and what you need to survive actually)
The oxygen your body needs comes from the air you breathe. When you inhale, your lungs take in oxygen from the air, and this oxygen is carried to all the cells in your body through your bloodstream to be used in various metabolic processes.
Your body needs more oxygen after and during exercise.
We breathe faster when we exercise to increase the amount of oxygen available to our bodies.
a human breaths 20 liters / minute with oxygen being 21% of the air this means +- 4liters / min intake although a lot of the oxygen leaves our body again when exhaling (4% oxygen gets taken in by our body, and 4% extra CO2 is exhaled) this means a human body takes about 0.16liters of oxygen / minute
We breathe in air which contains oxygen. Our body needs oxygen to make energy to order to move and function.