When we inhale we take in oxygen and when we exhale we release carbon dioxide which is one of the waste products of our body. When we take in oxygen, it is directed to our lungs from where it enters blood and goes around our body to every organ. Every part of our body and supplies oxygen to them. Organs and parts of our body need this oxygen to give them energy to function. When blood gives oxygen to the body and all the organs, in turn the organs give back carbon dioxide to the blood and this carbon dioxide then reaches the lungs through blood and is exhaled out.
Aerobic respiration is a chemical reaction in which oxygen is used to break glucose down into carbon dioxide and water. Energy is also released in this process.
Glucose + oxygen -> carbon dioxide + water + energy
C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP
In plant and animal cells, it is a process in which energy is released from food molecules such as glucose without oxygen. Some aerobic plants and animals are able to use anaerobic respiration for short periods of time. For example, during a sprint, human muscles can respire Anaerobically. Unfortunately, lactic acid is produced and works until the muscles cannot continue working. Anaerobic respiration in humans is less efficient than aerobic respiration at releasing energy, but releases energy faster. This explains why humans can run faster in a sprint