Cells utilize oxygen for metabolism and produce energy along with substances like carbon dioxide. Humans have a well-developed respiratory system comprising of two lungs and associated air passages to perform respiration.
The first step in respiration is breathing by which atmospheric air is taken in and the alveolar air is released out. Exchange of O2 and CO2 between deoxygenated blood and alveoli, transport of these gases throughout the body by blood and tissues and utilization of O2 by the cells are the other steps involved.
Oxygen is transported mainly as oxyhaemoglobin. O2 gets bound to haemoglobin and is easily dissociated in the target tissues.
Respiratory rhythm is maintained by the respiratory centre in the medulla region of the brain. A pneumotaxic centre in the brain and a chemosensitive area in the medulla can alter respiratory mechanism.