Do you even lift?
Do you do any aerobic exercises? When you exercise for a really long time, sometimes your muscles will ache due to lack of oxygen. These exercises require oxygen for your cells, which go through a whole process called Cellular Respiration, where by the name you could tell, your cells need to ‘breath’
It all starts from the first thing needed, Glucose, which is gained from the food you eat. Glucose goes through a process called Glycolysis, which occurs in the cell’s cytoplasm, where the glucose ( C6H12O3 ) is split into pyruvic acid, a three carbon compound, It becomes two ( C3H6O3 )’s. This process requires two ATP to start and produces two ATP. So far, a net yield of zero.
The pyruvic acid, now :( C3H5O3 ) used two hydrogens for the last process. The next process is the Kreb’s Cycle. This process takes place in the mitochondria. The rest of the hydrogens are used to make NAD+, a carrier molecule, into NADPH then the CO exits the mitochondria and exhaled as carbon dioxide. The hydrogen also makes FAD into FADH2. This process produces two ATP. We get a net yield of two.
In the last process, Electron Transport Chain, the reactants will be the NADH and FADH2. They go to apart in the mitochondria, where they pass through a membrane. The NAD+ and FAD leave to get more high energy electrons. The high energy electrons enter the membrane and the energy is extracted into the intermembrane space, getting positively charged. The H+ is then shot out of the membrane through the ATP synthase, and grabs a phosphate group. This produces H2O and 34 ATP! Total ATP is 38 net yield of 36 ATP.
This is how your body uses oxygen for exercises and produces water. This water is usually used for other cell needs, or exhaled. All of this happens when you take a simple breath!