<P> The lungs are the primary organs of the respiratory system in humans and many other animals including a few fish and some snails . In mammals and most other vertebrates , two lungs are located near the backbone on either side of the heart . Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream , and to release carbon dioxide from the bloodstream into the atmosphere , in a process of gas exchange . Respiration is driven by different muscular systems in different species . Mammals , reptiles and birds use their different muscles to support and foster breathing . In early tetrapods , air was driven into the lungs by the pharyngeal muscles via buccal pumping , a mechanism still seen in amphibians . In humans , the main muscle of respiration that drives breathing is the diaphragm . The lungs also provide airflow that makes vocal sounds including human speech possible . </P>
<P> The lungs are the primary organs of the respiratory system in humans and many other animals including a few fish and some snails . In mammals and most other vertebrates , two lungs are located near the backbone on either side of the heart . Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream , and to release carbon dioxide from the bloodstream into the atmosphere , in a process of gas exchange . Respiration is driven by different muscular systems in different species . Mammals , reptiles and birds use their different muscles to support and foster breathing . In early tetrapods , air was driven into the lungs by the pharyngeal muscles via buccal pumping , a mechanism still seen in amphibians . In humans , the main muscle of respiration that drives breathing is the diaphragm . The lungs also provide airflow that makes vocal sounds including human speech possible . </P>
where does the actual gas exchange take place most often
where does the actual gas exchange take place most often
lungs
lungs