Explain the differences between aerobic and anaerobic respiration (in animals), when the transition occurs and why there is a need for the body to remove lactic acid that is built up during the process?

Respiration occurs within the mitochondria, an organelle in all our living cells. Aerobic respiration occurs when there is sufficient oxygen for the body to completely breakdown glucose into carbon dioxide and water, whereas when there is insufficient oxygen anaerobic occurs (for instance during intense exercise). Anaerobic respiration is when there is lactic acid produced, which builds up in the muscles and tissues and must be converted into carbon dioxide. The cramps that occur within muscles during exercise are due to this lactic acid buildup, and to remove this the oxygen debt (i.e. the amount of oxygen owed to the body to oxidize lactic acid into Co2 and water) must be met. Hence, one tends to pant and breathe heavily and deeper after exercise to gain enough oxygen to remove the lactic acid, as it is toxic