English: Anatomy of the respiratory system, showing the trachea and both lungs and their lobes and airways. Lymph nodes and the diaphragm are also shown. Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset). (1) Note: The text and images above are in the public domain and were reproduced or adapted from the websites of the National Cancer Institute (NCI): http://www.cancer.gov/ and http://visualsonline.cancer.gov/.