oxygen deprivation or anoxic (depending on degree)
the clip and the light that you are talking about is a pulse oximeter and this machine measure the hemoglobin that is bind to oxygen in your blood. The hemoglobin is what transport oxygen to your cells and tissues. If you have a low hemoglobin level but they're all bind to oxygen the reading will be good but your tissues and cells are not receiving enough oxygen. That can be one of the reason you're feeling you don't get enough air.Otherwise it could be because of congestion in your lungs even if you're getting enough oxygen.
Yes, cells need oxygen to produce energy. Without enough oxygen, cells will not be able to function properly and may eventually die. This can lead to tissue damage and organ failure in the body.
Smoking increases the amount of Carbon Monoxide in your body and you have a small amount of Oxygen in your body, so not enough of Oxygen goes to your brain and organs and you have less energy.
Anoxia
oxygen
The oxyhaemoglobin will break down and oxygen will release. :)
blood delivers oxygen to the cells
All cells need oxygen to live. When they don't get enough oxygen, cellular metabolism is disrupted and eventually cells begin to die.
When the blood reaches cells that do not have enough oxygen, they may not be able to function properly. This can lead to cell damage or death. The body may respond by increasing blood flow to the area or causing other cells to release additional oxygen to help support the oxygen-deprived cells.
You will pass out and your body will begin to shut down as the cells need oxygen to live.
Lactic acid fermentation
Hemoglobin is a protein that is carried by red blood cells. Homoglobin needs oxygen to be carried by the cells. Without it, the body does not receive enough protein.