Describe the path that oxygen takes as it enters the respiratory system.

The path that oxygen takes through the respiratory system is identified below in a flowchart format:

Mouth or Nostrils of the Nose → Nasopharynx → Oral Pharynx → Glottis → Trachea → Lungs (Right and Left Bronchi → Bronchioles → Alveoli)

Gas exchange occurs between the alveoli sacs and small capillaries of the circulatory system. Via this exchange, oxygen is delivered from the lungs to the bloodstream. The oxygen attaches to the hemoglobin of red blood cells. The red blood cells then transport the oxygen to cells, such as those located in your muscles.

The oxygen is used by the mitochondria of eukaryotic cells in the process that is known as cellular respiration. During cellular respiration, oxygen gas and the sugar glucose are converted into water, carbon dioxide gas, and an energy source called adenosine triphosphate (ATP).