The primary function of the respiratory system is to provide needed by cells to metabolize nutrient molecules, and to expel , a byproduct of metabolism. this process of gas exchange is called .

Oxygen; cabondioxide,Cellular respiration

Explanation:

Breathing a Mechanism of respiration supplys Oxygen molecules which diffuses in through the respiratory tracts to reach the alveolar sacs for diffusion to the blood enroute the body cells.

These Oxygen molecules are use for combustion of metabolites e. g glucose.The reactions take place in the Matix of Mitochondrial via Citric Acid Cycle.where ATPs were produced.Molecules of Carbondioxide were librated, as byproducts.

Co factors NAD+and FAD+ trapped H+ atoms and take these accros the intramembranes . The protons were moved down their concentration gradients to supply more ATPs.The energy for the proton pump was supplied by electron chains transport system. The electrons were supplied by the splitting of Hydrogen atom carried by the co-factors to:protons and electrons.

This redox process of ATPs production is called Oxidative phosphorylation.