The respiratory system consists of the upper and lower respiratory tract. The upper tract includes the nose, mouth, pharynx and larynx. The lower tract includes the lungs, bronchi, bronchioles and alveoli. The lungs are located in the thoracic cavity and are protected by the ribs and pleura. During breathing, the diaphragm and intercostal muscles work to expand the lungs and draw in air. Oxygen and carbon dioxide are exchanged between the alveoli and blood vessels to oxygenate tissues and remove carbon dioxide.
Related topics: