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Our lungs contract and expand with approximately 12 to 18 breaths per minute. During this time, each lung captures oxygen from the air and supplies it throughout the body via the bloodstream and, at the same time, expels carbon dioxide, which is formed as a waste product of metabolism. Lungs are spongy organs, filled with air, located inside the thoracic cavity. In this article, we discuss how air enters the upper respiratory tract and eventually ends up in tiny alveoli where gas exchange takes place.

Upper Respiratory Tract

The upper respiratory tract consists of the nasal cavity, pharynx, and larynx; the lower respiratory tract comprises the trachea, bronchi, and lungs. The nasal cavity has a large surface area and its function is to adjust the temperature of ...

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